Msrp toc

ORNL-2474 MOLTEN-SALT REACTOR PROGRAM QUARTERLY PROGRESS REPORT For Period Ending January 31, 1958 SUMMARY

1 PART 1. REACTOR DESIGN STUDIES

1.1. REACTOR DESIGN Study Layouts of Reactor System Nuclear Calculations Univac-Ocusol Reactor Calculations Oracle Calculations IBM-704 Codes Fuel Fill-and-Drain System Design Design of a Hydrostatic Bearing for a Molten Salt Pump Impeller

9 9 12 12 14 15 15 16

1.2. COMPONENT DEVELOPMENT AND TESTING Fuel Pump Design and Development Pump Design Studies Development Tests of Salt-Lubricated Bearings Development Tests of Mechanical Shaft Seals Development Tests of Oil-Lubricated Bearings Irradiation and Endurance Tests of Bearings and Seals Development of Techniques for Remote Maintenance of the Reactor System Mechanical Joint Development Remote Manipulation Techniques Heater-Insulation Units for Remote Application Maintenance Demonstration Facility Heat Exchanger Development Design, Construction, and Operation of Materials Testing Loops Forced-Circulation Loops In-Pile Loops

18 18 18 18 19 20 20 20 20 24 25 26 27 27 27 32

1.3. ENGINEERING RESEARCH Hydrodynamic Studies of MSR Core Physical Property Measurements Molten Salt Heat Transfer Studies

35 35 37 37

1.4. ADVANCED REACTOR STUDIES A Molten Salt Natural-Convection Reactor Salt-Cooled Heat Exchangers Helium-Cooled Heat Exchangers for Steam Cycle Helium-Cooled Heat Exchanger for Gas-Turbine Cycle Comparison of the Various Cooling Systems Comparison of Natural-Convection System with Forced-Convection System High-Flux Reactors

41 41 42 42 43 44 44 44

PART 2. MATERIALS STUDIES 2.1. METALLURGY Dynamic Corrosion Studies Thorium-Bearing Salts in Thermal-Convection Loops Uranium-Bearing Salts and Coolant Salts in Thermal-Convection Loops Results of Examination of Samples Removed from Forced-Circulation Loop CPR General Corrosion Studies Effect of Carburization on Reactor Structural Materials Corrosion of Brazing Alloys by Fuel Salts Corrosion of INOR-8 Welds by NaK and by Fuel Salts Physical Properties of INOR-8 Mechanical Properties of INOR-8 Welding and Brazing Studies Metal Seals for Remote-Disconnect Flanged Joints Welding of INOR-8 Tubing Evaluation Tests for Welds Examination of INOR-8 Forced-Circulation Loop That Failed During Initial Heating Fabrication of Test Components Development of Nondestructive Testing Techniques Evaluation of INOR-8 Tubing Cladding Thickness Measurements and Bond Inspections Inspection Results Material Inspection Weld Inspection Failure Analyses

51 51 51 52 54 54 54 59 60 62 63 64 64 65 67 71 73 75 75 77 77 77 78 78

2.2. RADIATION DAMAGE In-Pile Thermal-Convection Loop Tests In-Pile Static Capsule Tests

79 79 80

2.3. CHEMISTRY Phase Equilibrium Studies Systems Containing UF4 and/or ThF4 Solubility and Stability of PuF3 in Molten Fluorides Fused Chlorides as Secondary Heat Transfer Fluids Vapor Pressures of LiF-BeF2 Mixtures Fuel Reprocessing Solubility of Noble Gases in Molten Fluoride Mixtures Solubility of HF in Molten Fluorides Solubilities of Fission-Product Fluorides Order of Oxide Precipitation in Fluoride Salt Melts Chemical Reactions of Oxides with Fluorides in LiF-KF Lithium Recovery from NaF-KF-LiF Melts Chemistry of the Corrosion Process Activity Coefficients of CrF2 in NaF-ZrF4 Solubility of FeF2 in LiF-BeF2 Use of 51Cr to Study Chromium Migration in Polythermal Inconel-Molten Salt Systems Activity of Nickel in Nickel-Molybdenum Alloys Production of Purified Mixtures Preparation of Pure Fluorides Small-Scale Purification Operations Preparation of Material for In-Pile Loop Transfer and Service Operations

81 81 81 88 90 91 91 91 93 94 97 99 101 105 105 107 107 111 113 113 113 113 113

ORNL-2626 MOLTEN-SALT REACTOR PROGRAM QUARTERLY PROGRESS REPORT For Period Ending October 31, 1958 SUMMARY

iii PART 1. REACTOR DESIGN STUDIES

1.1. CONCEPTUAL DESIGN STUDIES AND NUCLEAR CALCULATIONS Interim Design Reactor Fuel Fill-and-Drain System Fuel-to-Steam Heat Transfer Comparative Costs of Several Systems Experimental Reactor Calculations Nuclear Calculations Nuclear Characteristics of Homogeneous, Two-Region, Molten-Fluoride-Salt Reactors Fueled with U233 Blanket Fissions in the Reference Design Reactor Comparison of Ocusol and Compone Calculations Heterogeneous Reactors Gamma-Ray Heating Calculations

3 3 3 3 4 6 6

1.2. COMPONENT DEVELOPMENT AND TESTING Fuel Pump Development Development Tests of Salt-Lubricated Bearings Development Tests of Conventional Bearings Mechanical Seals Radiation-Resistant Electric Motors for Use at High Temperatures Design Studies of Fuel Pumps Frozen-Lead Pump Seal Development of Techniques for Remote Maintenance of the Reactor System Mechanical Joint Development Evaluation of Expansion Joints for Molten-Salt Reactor Systems Remote Maintenance Demonstration Facility Heat Exchanger Development Al2Cl6 Thermal-Convection Loop Molten-Salt Heat Transfer Coefficient Measurement Design, Construction, and Operation of Materials Testing Loops Forced-Circulation Loops In-Pile Loops

19 19 19 20 21 22 22 23 25 25 32 35 37 37 38 39 39 42

1.3. ENGINEERING RESEARCH Physical Property Measurements Enthalpy and Heat Capacity Surface Tension Apparatus Fabrication and Calibration Molten-Salt Heat-Transfer, Studies

44 44 44 45 46 46

1.4. INSTRUMENTATION AND CONTROLS Resistance-Type Continuous Fuel Level Indicator

47 47

6 9 10 11 11

1.5. ADVANCED REACTOR DESIGN STUDIES Low-Enrichment Graphite-Moderated Molten-Salt Reactors A Natural-Convection Molten-Salt Reactor

48 48 48

PART 2. MATERIALS STUDIES 2.1. METALLURGY Dynamic Corrosion Studies Inconel Thermal-Convection Loop Tests INOR-8 Thermal-Convection Loop Tests Inconel Forced-Circulation Loop Tests Results of Examination of Samples Removed from INOR-8 Forced-Circulation Loop 9354-1 Material Inspection General Corrosion Studies Carburization of Inconel and INOR-8 by Sodium-Graphite Systems Carburization of INOR-8 by Fuel 130-Graphite Systems UO2 Precipitation in Fused Fluoride Salts in Contact with Graphite Precious-Metal-Base Brazing Alloys in Fuel 130 Mechanical Properties of INOR-8 Influence of Composition on Properties of INOR-8 High-Temperature Stability of INOR-8 Welding and Brazing Studies INOR-8 Weldability Brazing of Thick Tube Sheets for Heat Exchangers Fabrication of Pump Components

53 53 53 53 53

2.2. RADIATION DAMAGE INOR-8 Thermal-Convection Loop for Operation in the LITR Graphite Capsules Irradiated in the MTR

76 76 76

2.3. CHEMISTRY Phase Equilibrium Studies Systems Containing UF4 and/or ThF4 Solubility of PuF3 in LiF-BeF2 Mixtures Fission-Product Behavior Solubility of Noble Gases in Molten Fluoride Mixtures Solubility of HF in LiF-BeF2 Mixtures Solubilities of Fission-Product Fluorides in Molten Alkali FluorideBeryllium Fluoride Solvents A Simple Method for the Estimation of Noble Gas Solubilities in Molten Fluoride Mixtures Chemical Reactions of Oxides with Fluorides in LiF-BeF2 Chemistry of the Corrosion Process Activities in Metal Alloys Surface Tensions of BeF2 Mixtures Disproportionation of Chromous Fluoride Effect of Fuel Composition on the Equilibria 3CrF2↔2CrF3 + Cr° and 3FeF2↔2FeF3 + Fe° Activity Coefficients of CrF2 in NaF-ZrF4 Equilibrium Amounts of CrF2 in Molten Salts Containing UF4 Which are in Contact with Inconel Chromium Diffusion in Alloys Corrosion of Metals by Aluminum Chloride Corrosion of Inconel by Aluminum Chloride Vapor in a Fused Silica Container

78 78 78 80 83 83 85

56 57 57 57 59 61 64 64 65 67 68 68 71 73

87 90 92 93 93 94 94 95 96 98 99 100 100

Corrosion of Inconel by Aluminum Chloride Vapor in an All-Metal System Significance of Experimental Results Theoretical Considerations of Aluminum Chloride Vapor Corrosion Structural Metal Considerations Gaseous Aluminum Chloride as a Heat Exchange Medium Permeability of Graphite by Molten Fluoride Salts Preparation of Purified Materials Preparation of Pure Fluoride Compounds Production-Scale Operations Experimental-Scale Operations 2.4. FUEL PROCESSING Flowsheet for Fluoride Volatility and HF Dissolution Processing of Molten-Salt Reactor Fluids Experimental Studies of Volatility Step Solubilities of LiF-BeF2 Salts in Aqueous HF

100 101 101 102 103 107 107 107 108 108 110 110 110 112

ORNL-2684 MOLTEN-SALT REACTOR PROJECT QUARTERLY PROGRESS REPORT For Period Ending January 31, 1959 SUMMARY

iii PART 1. REACTOR DESIGN STUDIES

1.1. CONCEPTUAL DESIGN STUDIES AND NUCLEAR CALCULATIONS Design of a 30-MWe, One-Region, Experimental Molten-Salt Reactor Reactor System Power Plant Arrangement Fuel Sampling and Enriching Mechanism System Preheating Device Off-Gas System Valves Preliminary Design of a 315 MWe Graphite-Moderated Molten-Salt Power-Reactor Nuclear Calculations Reactivity Effects in Experimental Molten-Salt Reactor Neutron and Gamma Ray Activity in the Secondary Heat Exchanger of the Interim Design Reactor Effect of Ion-Exchange Processing of Rare Earth Fission Products on Performance of Interim Design Reactor Multigroup Oracle Programs for Heterogeneous Reactor Computations Oracle Program GHIMSR for Gamma-Heating Calculations Initial and Long-Term Nuclear Performance Without Fuel Processing of Low-Enrichment, One-Region, Graphite-Moderated, Unreflected, Molten-Salt Reactor Initial and Long-Term Nuclear Performance Without Fuel Processing of One-Region, Graphite-Moderated, Unreflected, Th232-Conversion, Molten-Salt Reactor Initial Nuclear Performance of One-Region, Graphite-Moderated, Graphite-Reflected, Th232-Conversion, Molten-Salt-Reactor

3 3 3 5 9 12 12 18 23 23

1.2. COMPONENT DEVELOPMENT AND TESTING Salt-Lubricated Bearings for Fuel Pumps Hydrodynamic Journal Bearings Hydrodynamic Thrust Bearings Test Pump Equipped with a Salt-Lubricated Journal Bearing Hydrostatic Bearings Bearing Mountings Conventional Bearings for Fuel Pumps Mechanical Seals for Fuel Pumps Labyrinth and Split-Purge Arrangement Bellows-Mounted Seal Pump Endurance Testing Frozen-Lead Pump Seal Techniques for Remote Maintenance of the Reactor System Mechanical Joint Development Remote Maintenance Demonstration Facility Molten-Salt Heat-Transfer-Coefficient Measurement Triplex-Tubing Heat Exchanger Development

38 38 38 39 39 41 41 41 42 42 42 42 43 47 47 51 51 54

24 25 27 30 30 31 34

Evaluation of Expansion Joints for Molten-Salt Reactor Systems Design, Construction, and Operation of Materials Testing Loops Forced-Circulation Loops In-Pile Loops 1.3. ENGINEERING RESEARCH Physical Property Measurements Viscosity Enthalpy and Heat Capacity Molten-Salt Heat Transfer Studies

54 59 59 63 65 65 65 67 67

PART 2. MATERIALS STUDIES 2.1. METALLURGY Dynamic Corrosion Studies Thermal-Convection Loop Tests Forced-Circulation Loop Tests General Corrosion Studies Carburization of Inconel and INOR-8 in Systems Containing Sodium and Graphite Carburization of Inconel and INOR-8 in Systems Containing Fuel 130 and Graphite Uranium Precipitation From Fused Fluoride Salts in Contact with Graphite Fused Fluoride Salt Penetration Into Graphite Mechanical Properties of INOR-8 Materials Fabrication Studies Triplex Tubing for Heat Exchangers High-Temperature Stability of INOR-8 Commercial Production of INOR-8 Evaluations of Composites of INOR-8 and Type 316 Stainless Steel Welding and Brazing Studies Heat Exchanger Fabrication Welding of INOR-8 Welding of Dissimilar Metals Pump Component Fabrication

75 75 75 76 76 76 78 80 81 82 85 85 87 87 87 88 88 90 95 96

2.2. CHEMISTRY AND RADIATION DAMAGE Phase Equilibrium Studies Systems Containing UF4 and/or ThF4 The System LiF-PuF3 The System KF-LiF-BeF2 Compatibility of Fuel with Chloride Coolants Fission-Product Behavior Effect of UF4 on Solubility of CeF3 in LiF-BeF2 Solvents Removal of Traces of SmF3 by the Addition of CeF3 to LiF-BeF2-UF4 Chemical Reactions of Oxides with Fluorides Chemistry of the Corrosion Process Activity Coefficients of CrF2 in NaF-ZrF4 Chromium Diffusion in Alloys Sampling of Operating Loops Effect of Fuel Composition on Corrosion Equilibria Vapor Pressures of Molten Salts BeF2 Mixtures UF4 Aluminum Chloride Vapor as a Heat Transfer Medium and Turbine Working Fluid Estimation of Thermodynamic Properties Corrosion of Nickel by AlCl3

98 98 98 98 99 99 100 100 100 101 102 102 103 106 106 107 107 107 108 108 109

Permeability of Graphite by Molten Fluoride Mixtures Effects of Thermal Cycling on Salt Stability Radiation Damage Studies INOR-8 Thermal-Convection Loop for Operation in the LITR In-Pile Static Corrosion Test Preparation of Purified Materials Fluorides of Chromium Synthesis of Simple Fluorides by Reactions with Stannous Fluoride Experimental-Scale Purification Operations Transfer and Service Operations 2.3. FUEL PROCESSING Solubility of Neptunium in Aqueous HF Solutions Solubility of Corrosion Product Fluorides in HF Solvent Solubilities of Uranium and Thorium Tetrafluoride in HF Solvent

110 111 112 112 112 112 112 114 114 114 115 115 117 118

ORNL-2723 MOLTEN-SALT REACTOR PROJECT QUARTERLY PROGRESS REPORT For Period Ending April 30, 1959 SUMMARY

vi PART 1. REACTOR DESIGN STUDIES

1.1. NUCLEAR CALCULATIONS AND DESIGN STUDIES Nuclear Calculations Effect of Ion-Exchange Processing of Rare-Earth Fission Products on Performance of Interim Design Reactor Fueled with U233 Nuclear Performance of a One-Region, Graphite-Moderated, Unreflected, Thorium-Conversion, Molten-Salt-Fueled Reactor Initial Nuclear Performance of One-Region, Graphite-Moderated, Graphite-Reflected, Thorium-Conversion, Molten-Salt-Fueled Reactors Nuclear Performance of Two-Region, Graphite-Moderated, Molten-Salt-Fueled, Breeder Reactor Effects of Fast Neutron Reactions in 9Be on Reactivity of Molten-Salt Reactors Oracle Code MSPR-Cornpone 020 Design of 30-MWe Experimental Reactor Fuel Drain System Gamma Heating in the Core Vessel of the 30-MWe Experimental Reactor

3 3

1.2. COMPONENT DEVELOPMENT AND TESTING Salt-Lubricated Bearings for Fuel Pumps Hydrodynamic Journal Bearings Hydrodynamic Thrust Bearings Test of Pump Equipped with One Salt-Lubricated Journal Bearing Bearing Mountings Mechanical Seals for Pumps Pump Endurance Testing Frozen-Lead Pump Seal Techniques for Remote Maintenance of the Reactor System Design, Construction, and Operation of Materials Testing Loops Forced-Circulation Loops In-Pile Loops

24 24 24 25 25 25 27 27 27 28 32 32 35

1.3. ENGINEERING RESEARCH Physical Property Measurements Enthalpy and Heat Capacity Viscosity Surface Tension Heat-Transfer Studies Hydrodynamic Studies

37 37 37 39 39 41 44

1.4. INSTRUMENTS AND CONTROLS Molten-Salt-Fuel Level Indicators INOR-8 High-Temperature Pressure Transmitters

47 47 47

3 3 9 10 14 20 21 22 22

PART 2. MATERIALS STUDIES 2.1. METALLURGY Dynamic Corrosion Studies INOR-8 Thermal-Convection Loops Inconel Thermal-Convection Loops General Corrosion Studies Penetration of Graphite by Molten Fluoride Salts Uranium Precipitation from Molten Fluoride Salts in Contact with Graphite Thermal-Convection-Loop Tests of Brazing Alloys in Fuel 130 Thermal-Convection-Loop Tests of the Compatibility of INOR-8, Graphite, and Fuel 130 Mechanical Properties of INOR-8 Creep Tests Fatigue Studies Shrinkage Characteristics of INOR-8 Materials Fabrication Studies Effect on INOR-8 of Aging at High Temperatures Triplex Heat Exchanger Tubing Welding and Brazing Studies Procedures for Welding INOR-8 Mechanical Properties of INOR-8 Welds Fabrication of Apparatus for Testing the Compatibility of Molten Salts and Graphite

51 51 52 54 54 54 58 60

2.2. CHEMISTRY AND RADIATION DAMAGE Phase Equilibrium Studies The System LiF-BeF2-ThF4 The System NaF-BeF2-ThF4 The System NaF-ThF4-UF4 The System SnF2-NH4HF2 Solubility of PuF3 in Converter Fuels Separation of 7LiF from 7LiF-BeF2 Fission-Product Behavior Precipitation of SmF3 with CeF3 Chemical Reactions of Oxides with Fluorides in Molten-Fluoride-Salt Solvents Gas Solubilities in Molten Fluoride Salts Solubility of Neon in LiF-BeF2 Solubility of CO2 in NaF-BeF2 Chemistry of the Corrosion Process Samples from Operating Loops Radioactive Tracer Analyses for Iron in Molten Fluoride Salts Activities in Metal Alloys Vapor Pressures of Molten Salts Permeability of Graphite by Molten Fluoride Salts Radiation Damage Studies INOR-8 Thermal Convection Loop for Operation in the LITR In-Pile Static Corrosion Tests Preparation of Purified Materials Purification, Transfer, and Service Operations Fuel Replenishment Tests Pure Compounds Prepared with Molten Ammonium Bifluoride Reaction of Chromous Fluoride with Stannous Fluoride

75 75 75 77 78 78 80 80 81 81 82 85 85 85 86 86 87 87 88 88 91 91 91 92 92 92 93 94

2.3. FUEL PROCESSING

95

61 63 63 63 63 65 65 67 68 68 70 73

ORNL-2799 MOLTEN-SALT REACTOR PROGRAM QUARTERLY PROGRESS REPORT For Period Ending July 31, 1959 SUMMARY

iii PART 1. REACTOR DESIGN STUDIES

1.1. NUCLEAR CALCULATIONS AND DESIGN STUDIES Nuclear Performance of a Two-Region, Graphite-Moderated, Molten-Salt Breeder Reactor

3 3

1.2. COMPONENT DEVELOPMENT AND TESTING Molten-Salt-Lubricated Bearings for Fuel Pumps Hydrodynamic Journal Bearings Hydrodynamic Thrust Bearings Test of Pump Equipped with One Molten-Salt-Lubricated Journal Bearing Bearing Mountings Self-Welding of INOR-8 Mechanical Seals for Pumps Pump Endurance Testing Remote Maintenance Demonstration Facility Frozen-Lead Pump Seal Mechanical Joints for the Reactor System Design, Construction, and Operation of Materials-Testing Loops Forced-Circulation Corrosion Loops In-Pile Loops

15 15 15 18 18 19 19 19 19 20 30 30 31 31 31

1.3. ENGINEERING RESEARCH Physical-Property Measurements Viscosity Enthalpy and Heat Capacity Thermal Expansion Heat-Transfer Studies

34 34 34 37 39 39

1.4. INSTRUMENTS AND CONTROLS Molten-Salt-Fuel Level Indicators

43 43

PART 2. MATERIALS STUDIES 2.1. METALLURGY Dynamic Corrosion Studies INOR-8 Thermal-Convection Loops Inconel Thermal-Convection Loops INOR-8 Forced-Circulation Loops General Corrosion Studies Carburization Tests on Inconel and INOR-8 in Systems Containing Fuel 130 and Graphite Sodium-Graphite Carburization Tests Penetration of Graphite by Molten Fluorides Removal of Oxide Contaminants from Graphite Mechanical Properties of INOR-8

47 47 47 50 55 59 59 60 61 62 63

Materials Tensile Properties Creep Tests Relaxation Tests Dimensional Instability Fatigue Studies Carburization Materials Fabrication Studies Triplex Heat Exchanger Tubing Welding and Brazing Studies Welding of INOR-8

64 64 65 65 65 66 66 67 67 71 71

2.2. CHEMISTRY AND RADIATION EFFECTS Phase Equilibrium Studies The System NaF-ThF4-UF4 The System NaF-BeF2-ThF4 The System NaF-PuF3 Cryoscopy in NaF Gas Solubilities in Molten Fluorides Solubility of Xenon in LiF-BeF2 Solubility of CO2 in NaF-BeF2 Fission-Product Behavior Solubility of Rare-Earth Fluorides Precipitation of Rare-Earth Fluorides by Cooling Reactions of UF4 with Oxides in Molten Fluoride Solvents Reaction of UF4 with BeO Reaction of UF4 with Strontium Oxide Reaction of UF4 with Structural-Metal Oxides Reactions of UF4 with Air Chemistry of Corrosion Processes Solubility and Thermodynamic Properties of NiF2 in LiF-BeF2 Activities from Vapor Pressure Measurements Tracer Analyses for Determining Efficacy of Reducing Agents Analyses of Corrosion-Test Loops Stability of Zirconium Monochloride in Air Graphite Compatibility Studies Long-Term Loop Tests of Graphite with Circulating Fuel Permeability of Graphite by Molten Fluorides Preparation of Purified Materials Purification, Transfer, and Service Operations Reactions of Stannous Fluoride Radiation Effects INOR-8 Thermal-Convection Loop for Operation in the LITR In-Pile Static Corrosion Tests

73 73 73 76 76 78 78 78 79 79 79 80 81 81 83 83 83 85 85 87 88 88 89 89 89 90 93 93 94 94 94 94

2.3. FUEL PROCESSING UF6 Solubility in HF-ClF3 Separation of LiF from CsF

96 96 97

ORNL-2890 MOLTEN-SALT REACTOR PROGRAM QUARTERLY PROGRESS REPORT For Period Ending October 31, 1959 SUMMARY

iii PART 1. ENGINEERING AND COMPONENT DEVELOPMENT

1.1. COMPONENT DEVELOPMENT AND TESTING Molten-Salt-Lubricated Bearings for Fuel Pumps Hydrodynamic Journal Bearings Hydrodynamic Thrust Bearings Test of Pump Equipped with One Molten-Salt-Lubricated Journal Bearing Self-Welding of INOR-8 Friction Tests on INOR-8 Mechanical Seals for Pumps MF Performance Loop Frozen-Lead Pump Seal Remote Maintenance Demonstration Facility Design, Construction, and Operation of Materials-Testing Loops Forced-Circulation Corrosion Loops Graphite-Metal Seal Tests In-Pile Loop

3 3 3 5 5 8 8 9 9 10 10 14 14 16 17

1.2. ENGINEERING RESEARCH Physical-Property Measurements Viscosity Enthalpy and Heat Capacity Thermal Expansion Heat-Transfer Studies

19 19 19 20 21 23

PART 2. MATERIALS STUDIES 2.1. METALLURGY Graphite Brazing Studies Dynamic-Corrosion Studies Forced-Convection-Loops General Corrosion Studies Permeation of Graphite by Molten Salts Removal of Oxide Contaminants from Graphite Compatibility of INOR-8 and Graphite in Direct Contact Brazing-Material Evaluation in Fuel 130

33 33 35 35 43 43 44 45 45

2.2. CHEMISTRY AND RADIATION EFFECTS Phase Equilibrium Studies The System BeF2-ThF4-UF4 The System BeF2-ThF4 The System NaF-BeF2-ThF4 Molten-Fluoride Solvents The Compound NaF-BeF2-3UF4 Gas Solubilities in Molten Fluorides

49 49 49 49 49 49 50 52

Solubility of HF in Fuel Solvents Fission-Product Behavior Exchange Reactions in Molten Fluorides Chemistry of Corrosion Processes Self-Diffusion Coefficients for Chromium in Nickel Alloys Chemical Analyses of Corrosion Test Loops Solubility of CrF2 in LiF-BeF2 (62-38 Mole %) Equilibrium Measurements on the Reduction of FeF2 by H2 in LiF-BeF2 Equilibrium Measurements on the Reduction of CrF2 and FeF2

by H2 in LiF-BeF2 (62-38 Mole %) Hygroscopic Behavior and Dehydration of Breeder Fuels Graphite Compatibility Studies Penetration of Graphite by Molten Fluorides Intercalation of Graphite with Molten Salts Diffusion of Rare-Earth Fission Products in Graphite Preparation of Purified Materials Technological Operations Molten Ammonium Bifluoride as a Reagent Radiation Effects Corrosion Tests Under Radiation 2.3. FUEL PROCESSING Thorium Fluoride Solubility in Aqueous NH4F Solutions Fuel-Component Solubility in ClF3-HF Fuel-Component Solubility in NO2-HF

52 54 54 55 55 59 61 62 63 65 65 66 67 67 67 68 69 69 70 70 71 71

ORNL-2973 MOLTEN-SALT REACTOR PROGRAM QUARTERLY PROGRESS REPORT For Periods Ending January 31 and April 30, 1960 SUMMARY

iii PART 1. ENGINEERING AND COMPONENT DEVELOPMENT

1.1 COMPONENT DEVELOPMENT AND TESTING Molten-Salt-Lubricated Bearings for Fuel Pumps Hydrodynamic Journal Bearings Test of Pump Equipped with One Molten-Salt-Lubricated Journal Bearing Self-Welding of INOR-8 Mechanical Seals for Pumps Loop for Study of MF-Pump Performance Frozen-Lead Pump Seal Remote-Maintenance Development Facility Design, Construction, and Operation of Materials Testing Loops Forced-Circulation Corrosion Loops Mechanical Joints Design and Testing of a Frozen-Salt Metal-to-Graphite Joint In-Pile Loops

3 3 3 3 5 7 7 8 8 12 12 19 19 21

1.2 ENGINEERING RESEARCH Physical-Property Measurements Enthalpy and Heat Capacity Thermal Conductivity Surface Tension Heat-Transfer Studies

23 23 23 23 26 27

PART 2. MATERIALS STUDIES 2.1 METALLURGY Dynamic Corrosion Studies Thermal-Convection-Loops Inconel Forced-Convection Loops INOR-8 Forced-Convection Loops Graphite Brazing Studies General Corrosion Studies Permeation of Graphite by Molten Salts Removal of Oxygen Contamination from Graphite Compatibility of INOR-8 and Graphite Corrosion Resistance of Brazing Alloys to Fluoride Fuel

33 33 33 36 38 45 53 53 59 60 62

2.2 CHEMISTRY AND RADIATION EFFECTS Phase Equilibrium Studies The System LiF-BeF2-ZrF4 The System NaF-ZrF4-ThF4 The System NaF-ThF4-UF4 Phase Diagrams for Fluoride Systems Fission-Product Behavior and Reprocessing Chemistry

65 65 65 65 66 68 68

Extraction of Uranium and Protactinium from LiF-BeF2-ThF4 Mixtures Chemistry of Corrosion Processes Effect of Oxide on LiF-BeF2-ThF4 and LiF-BeF2-ThF4-UF4 Mixtures Radiotracer Studies of the Role of Cr0 Diffusion as a Controlling Factor in Corrosion by Molten Fluorides The Free Energy of Formation of NiF2 Analysis of Corrosion Test Loops Corrosion Equilibria with Unalloyed Cr0 Melting Points of Chromous Fluoride and Chromic Fluoride Graphite Compatibility Intercalation of Graphite Permeation of Graphites by Molten Fluoride Fuels Radiation Effects Behavior of a Rare-Earth Fission Product in a Graphite-Molten-Salt System Preparation of Purified Materials Purification, Handling, and Service Operations 2.3 FUEL REPROCESSING NO2-HF Solutions Aqueous NH4F Protactinium Removal

68 74 74 75 79 80 81 82 82 82 83 84 84 86 86 87 87 87 88

ORNL-3014 MOLTEN-SALT REACTOR PROGRAM QUARTERLY PROGRESS REPORT For Period Ending July 31, 1960 SUMMARY

iii

PART I. MSRE DESIGN, COMPONENT DEVELOPMENT, AND ENGINEERING ANALYSIS 1. MSRE DESIGN 1.1 Introduction 1.2 MSRE Objectives 1.3 Conceptual Designs 1.4 The Reactor Core and Vessel 1.5 The Primary Heat Exchanger 1.6 Radiator 1.7 Drain Tanks 1.8 Equipment Arrangement 1.9 Design of Cover-Gas System 1.10 Design of the Remote-Maintenance System for MSRE 1.11 Modifications to Building 7503

1 1 2 2 4 8 10 11 12 18 19 22

2. COMPONENT DEVELOPMENT 2.1 Freeze Flange Development 2.2 Freeze Valves 2.3 Sampler-Enricher Development 2.4 MSRE Core Development 2.5 Remote Maintenance Development Facility 2.6 Forced-Circulation Corrosion Loops 2.7 Pump Development 2.7.1 MSRE Primary Pump 2.7.2 MSRE Secondary Pump 2.7.3 Advanced Molten-Salt Pumps 2.7.4 MF-F Pump Performance Loop 2.7.5 Frozen-Lead Pump Seal 2.7.6 MSRE Engineering Test Loop

24 24 25 25 27 27 28 29 29 30 30 31 31 31

3. REACTOR ENGINEERING ANALYSIS 3.1 Effects of Graphite Shrinkage Under Radiation in the MSRE Core 3.2 Temperature-Rise Effects in MSRE Cores with Round and Flat Fuel Channels 3.3 Temperature of Fuel in a Blocked Passage in the MSRE 3.4 MSRE Reactor Physics 3.4.1 Core Calculations 3.4.2 Gamma-Heating Calculations 3.4.3 Drain Tank Criticality 3.4.4 Pump-Bowl Fission-Product Activities 3.4.5 Cell Calculations 3.5 Analog Computer Study of MSRE Primary-System Flow Loss 3.5.1 Description of the System Simulated 3.5.2 Analog Computer Program 3.5.3 Simulator Operation 3.5.4 Conditions Used to Obtain Curves

32 32 34 39 41 41 44 44 45 45 45 46 48 49 49

PART II. MATERIALS STUDIES 4. METALLURGY 4.1 Dynamic-Corrosion Studies 4.1.1 Forced-Convection Loops 4.1.2 Microprobe Analyses of Surface Film 4.2 Welding and Brazing Studies 4.2.1 Solidified-Metal-Seal Development 4.2.2 Brazing of Graphite 4.2.3 Heat Exchanger Fabrication 4.2.4 Mechanical Properties of INOR-8 4.3 Permeation and Apparent-Density Uniformity in Large Pieces of Graphite 4.3.1 Permeation of AGOT and S-4 Graphites by Molten Salts at Different Pressures 4.4 Precipitation from Molten Fluoride Fuel in Contact with Various Volumes of Graphite 4.4.1 Removal of Contamination from Graphite 4.4.2 INOR-8 - Fuel - Graphite Carburization Tests 4.5 In-Pile Tests

55 55 55 56 58 58 59 63 64 67 67 69 69 70 71

5. CHEMISTRY 5.1 Phase Equilibrium Studies 5.1.1 MSRE Fuel and Coolant 5.1.2 Systems Containing ThF4 5.1.3 The System ZrF4-ThF4 5.2 Effect of Tetravalent Fluorides on the Freezing Point of Sodium Fluoride 5.2.1 Phase Diagram of Fluoride Systems 5.2.2 The System LiF-YF3 5.2.3 Melting Point of NiF2 5.3 Oxide Behavior 5.3.1 Oxide Behavior in Fuels 5.3.2 Zirconium Oxyfluoride and Attempted Preparation of Uranous Oxyfluoride 5.4 Graphite Compatibility 5.4.1 Removal of Oxide from Graphite by Treatment with Hydrogen 5.4.2 Behavior of Graphite when Wetted by a Molten Fluoride 5.5 Preparation of Purified Materials

72 72 72 72 74 75 77 78 79 79 79 80 80 80 81 81

6. ENGINEERING RESEARCH 6.1 Physical-Property Measurements 6.1.1 Surface Tension and Density 6.1.2 Heat Capacity 6.2 Heat-Transfer Studies

83 83 83 85 86

7. FUEL PROCESSING

88

ORNL-3122 MOLTEN-SALT REACTOR PROGRAM PROGRESS REPORT For Period From August 1, 1960, to February 28, 1961 SUMMARY

iii

PART I. MSRE DESIGN, COMPONENT DEVELOPMENT, AND ENGINEERING ANALYSIS 1. MSRE DESIGN 1.1 Introduction 1.2 Reactor Core and Vessel 1.3 Fuel Heat Exchanger 1.4 Radiator 1.5 Drain Tanks 1.6 Equipment Arrangement 1.7 Cover-Gas System 1.8 System Heaters 1.9 Design Status of Remote-Maintenance System 1.10 Reactor Control Design 1.11 Design Status of Building and Site 1.12 Reactor Procurement and Installation 1.12.1 Division of Work and Schedules 1.12.2 Procurement of Components

1 1 2 4 5 9 12 15 16 20 20 22 23 23 24

2. COMPONENT DEVELOPMENT 2.1 Freeze-Flange Development 2.1.1 MSRE 6-in. Flanges 2.1.2 Freeze-Flange Thermal-Cycle Tests 2.2 Freeze Valves 2.3 Heater Tests 2.3.1 Pipe Heaters 2.3.2 Core Heater 2.4 Sample-Enricher Development 2.4.1 Sampler-Enricher Concept 2.4.2 Sampler-Enricher Mockup 2.4.3 Solder Freeze Valve 2.5 MSRE Core Development 2.6 Helium Purification 2.7 MSRE Maintenance Development 2.7.1 Maintenance Philosophy 2.7.2 Remote-Maintenance Development Facility 2.7.3 Semidirect and Remote Tools 2.7.4 MSRE Model 2.8 Brazed-Joint Development 2.9 Mechanical-Joint Development 2.10 Forced-Circulation Corrosion Loops 2.11 Graphite-Molybdenum Compatibility Test 2.12 Pump Development 2.12.1 MSRE Fuel Pump 2.12.2 MSRE Coolant Pump 2.12.3 Advanced Molten-Salt Pumps

26 26 26 27 27 28 28 31 31 31 33 33 37 40 40 40 40 42 42 42 42 44 44 47 47 53 53

2.12.4 Frozen-Lead Pump Seal 2.13 MSRE Engineering Test Loop 2.14 MSRE Instrument Development 2.14.1 Thermocouple End Seals 2.14.2 Instrument and Power Disconnects 2.14.3 Pump-Bowl Level Indicator 2.14.4 Single-Point Level Device 3. REACTOR ENGINEERING ANALYSIS 3.1 Criticality Calculations 3.2 Reactivity Worth of Control Tubes 3.3 Preliminary Calculations for Core Containing INOR-8 Tubes 3.4 MSRE Biological Shielding and Associated Dose Rates

53 53 59 59 61 64 67 70 70 72 73 73

PART II. MATERIALS STUDIES 4. METALLURGY 4.1 Dynamic-Corrosion Studies 4.1.1 Status of Test Program 4.1.2 Examination of INOR-8 Loops 4.1.3 Examination of Inconel Loops 4.1.4 Molybdenum-Graphite Compatibility Tests 4.2 Welding and Brazing Studies 4.2.1 Welding of INOR-8 4.2.2 Solidified-Metal Seal Development 4.2.3 Sump-Type Seal Development 4.2.4 Metal-Fiber Seal Development 4.3 INOR-8 Development 4.3.1 Structural Stability of 18% Mo Alloys 4.4 Mechanical Properties of INOR-8 4.5 Impregnation of Graphite by Molten Salts 4.5.1 Permeation Screening Tests on Large and Small Pipe 4.5.2 Oxidation and Permeation 4.6 Precipitation of UO2 from Fluoride Salts 4.7 Precipitation of ZrO2 from MSRE Fuel 4.8 Removal of Oxygen Contamination from Graphite 4.8.1 Purging with Molten Fluorides 4.8.2 Purging with Ammonium Bifluoride 4.8.3 Reaction of INOR-8 with the Thermal-Decomposition Products of NH4F-HF

77 77 77 77 80 81 81 81 84 87 87 89 89 89 91 93 96 96 96 97 97 98 98

5. IN-PILE TESTS 5.1 Graphite-Fuel Capsule Experiments 5.2 Examination of Graphite Specimen from Experiment ORNL-47-2

100 100 102

6. CHEMISTRY 6.1 Phase Equilibrium Studies 6.1.1 The System LiF-BeF2-ZrF4-ThF4-UF4 6.1.2 The System LiF-BeF2-ZrF4 6.1.3 The System LiF-BeF2 6.1.4 Phase Equilibria in the System NaF-BeF2-ThF4 6.1.5 The System CsF-ZrF4 6.1.6 Crystal Structure of LiF-SbF5 6.1.7 Index to ORNL Work on Fused-Salt Phase Studies 6.1.8 Solubility of HF in Molten Fluorides 6.1.9 Solubility of BF3 in MSRE-Type Fuels 6.1.10 Freezing-Point Depressions in Sodium Fluoride

109 109 109 110 111 111 111 112 113 113 114 119

6.2 Oxide Behavior in Fuels 6.2.1 Identification of Oxides Precipitated from Fuels 6.2.2 Removal and Precipitation of Oxides from Fuels 6.3 Physical Properties 6.3.1 Density of MSRE Fuel 6.3.2 Stochastic Correlation of Densities of Molten Fluoride Fuels 6.3.3 Empirical Equation for Fluidity in LiF-BeF2-UF4 Systems 6.4 Graphite Compatibility 6.4.1 Xenon Diffusion in Graphite: Effects of Xenon Absorption in Molten-Salt Reactors Containing Graphite 6.4.2 Wetting of Graphite by MSRE Fused Salt 6.4.3 Retention of BF3 on Graphite in a Molten-Salt Reactor 6.5 Analytical Chemistry 6.5.1 Proposed Procedures for Analysis of the MSRE Fuel 6.5.2 Stripping Rate for CO2 from Water in an MSRE Pump-Demonstration System

119 119 120 122 122 123 125 126 126 129 130 130 130 134

7. ENGINEERING RESEARCH 7.1 Physical-Property Measurements 7.1.1 Enthalpy and Heat Capacity 7.1.2 Viscosity 7.2 Heat-Transfer Studies

138 138 138 139 140

8. FUEL PROCESSING 8.1 SbF5-HF Solutions 8.2 Dissolution Rates for MSRE Fuel Carrier Salt 8.3 Steady-State Fluorinator

143 143 144 145

ORNL-3215 MOLTEN-SALT REACTOR PROGRAM PROGRESS REPORT For Period From March 1 to August 31, 1961 SUMMARY

iii

PART I. MSRE DESIGN, COMPONENT DEVELOPMENT, AND ENGINEERING ANALYSIS 1. MSRE DESIGN 1.1 Introduction 1.2 Reactor Core and Vessel 1.3 Primary Heat Exchanger 1.4 Radiator 1.5 Fuel-Salt Drain Tanks 1.6 Equipment Layout 1.7 Cover-Gas System 1.8 System Heaters 1.9 Design Status of Remote-Maintenance Systems 1.9.1 Maintenance-Design Systems 1.9.2 Remote Maintenance by Manipulators 1.9.3 Remote Maintenance by Manual Operations 1.9.4 Assembly Jigs and Fixtures 1.9.5 Graphite-Sample Removal 1.10 Reactor-Control Design 1.11 Design Status of Building and Site 1.12 Reactor Procurement and Installation 1.12.1 Demolition and Minor Alteration Work to Building 7503 1.12.2 Major Modifications to Building 7503 1.12.3 Procurement of Materials 1.12.4 Procurement of Components 1.13 Reactor Instrumentation and Controls Design 1.13.1 Instrument Application Diagram 1.13.2 Electrical Control Circuitry 1.13.3 Layout 1.13.4 Main Control Board 1.13.5 MSRE Data-Handling Study 1.13.6 Single-Point Temperature Alarm System

1 1 2 4 4 4 8 11 12 13 13 13 14 15 15 16 19 19 19 20 20 20 21 21 21 21 22 24 25

2. COMPONENT DEVELOPMENT 2.1 Freeze-Flange Development 2.1.1 MSRE 5-in. Flanges 2.1.2 Freeze-Flange-Seal Test Facility 2.2 Freeze Valves 2.3 Heater Tests 2.3.1 Pipe Heaters 2.3.2 Core Heaters 2.4 Drain-Tank Coolers 2.5 Sampler-Enricher Development 2.5.1 Sampler-Enricher Concept 2.5.2 Solder-Freeze Valve 2.5.3 Sample Capsule

28 28 28 28 32 33 33 33 37 37 37 37 40

2.5.4 Sample-Transport Container and Removal Seal 2.5.5 Sampler-Enricher Design 2.6 MSRE Core Development 2.6.1 Heat Transfer Coefficients in the Lower Head of the Reactor Vessel 2.6.2 Fuel-Age Measurements in the Lower Head of the Reactor Vessel 2.6.3 Studies on the Disposition of Fine Particles in the Lower Head of the Reactor Vessel 2.6.4 Fluid-Dynamic-Induced Power Oscillations 2.6.5 Full-Scale MSRE Core Model 2.7 Helium Purification 2.8 Pump Development 2.8.1 MSRE Fuel Pump 2.8.2 Water Test of MSRE Coolant Pump 2.8.3 Advanced Molten-Salt Pumps 2.9 Graphite-Molybdenum Compatibility Test 2.10 MSRE Engineering-Test Loop 2.10.1 Oxide-Flush Run 2.10.2 Freeze-Valve Operation 2.10.3 Level Indicator for Molten Salt (Test Loop) 2.10.4 Graphite-Handling Facility 2.11 MSRE Maintenance Development 2.11.1 Maintenance Plan 2.11.2 Remote-Maintenance Mockup 2.11.3 MSRE Model 2.11.4 Portable Maintenance Shield 2.12 Brazed-Joint Development 2.13 Mechanical-Joint Development 2.14 Steam Generator 2.15 MSRE Instrument Development 2.15.1 Pump Bowl Level Indicator 2.15.2 Single-Point Level Indicator 2.15.3 Temperature Scanner 2.15.4 Thermocouple Attachments and End Seals 3. REACTOR ENGINEERING ANALYSIS 3.1 Reactor Physics 3.1.1 Analysis of MSRE Temperature Coefficient of Reactivity 3.1.2 Rod Worth, Flux, and Power Density Distributions in MSRE 3.1.3 Gamma-Ray and Fast-Neutron Heating in Thimbles 3.1.4 Reactors with INOR-8 Fuel Tubes 3.2 Nitrogen-16 Activity in Fuel Salt 3.3 Residual Activity in Pump Bowl and Heat Exchanger 3.4 Reactor-Cell Shielding 3.4.1 Top Shield 3.4.2 Side Shield

40 40 40 40 41 42 44 44 44 46 46 54 54 54 54 54 55 56 56 56 56 58 61 61 61 64 65 67 67 72 77 78 83 83 83 83 85 86 89 90 91 91 92

PART II. MATERIALS STUDIES 4. METALLURGY 4.1 Dynamic-Corrosion Studies 4.1.1 Examination of INOR-8 Forced-Convection Loops 4.1.2 Molybdenum-Graphite Compatibility Tests 4.1.3 Compatibility of INOR-8 - 2% Nb and Molten Fluorides 4.1.4 Fluoride-Salt Contamination Studies 4.2 INOR-8 Development 4.2.1 Structural Stability of Nickel-Based, 18% Molybdenum Alloys

93 93 93 96 99 99 100 100

4.2.2 Temperature Range of Melting for INOR-8 4.2.3 Specific Heat of INOR-8 4.3 Total Hemispherical Emittance of INOR-8 4.4 Welding and Brazing Studies 4.4.1 Welding of INOR-8 4.4.2 Metallographic Examination and Bend Tests on Welds 4.4.3 Transverse Tensile and Creep Tests 4.4.4 Welding of INOR-8 to Stainless Steel and Inconel 4.4.5 Remote Brazing 4.5 Mechanical Properties of INOR-8 4.6 Impregnation of Graphite by Molten Salts 4.7 Ammonium Bifluoride as an Oxygen-Purging Agent for Graphite 4.7.1 Removal of Oxygen from Graphite 4.7.2 Effects of the Thermal-Decomposition Products of Ammonium Bifluoride on INOR-8

102 103 103 106 106 106 106 108 109 112 113 114 114 115

5. IN-PILE TESTS 5.1 Graphite-Fuel Capsule Experiments

117 117

6. CHEMISTRY 6.1 Phase-Equilibrium Studies 6.1.1 Systems Involving NaF with ZrF4, ThF4, and UF4 and Other Constituents 6.1.2 The System NaF-ThF4-UF4 6.1.3 Stannous Fluoride as a Component of Reactor Fuels 6.2 Oxide Behavior in Fuels 6.2.1 Behavior of MSRE Fuel on Freezing and Effect of Segregation on Oxide Precipitation 6.2.2 Oxide Content of Fluoride Melts 6.3 Physical and Chemical Properties 6.3.1 Surface Tension Apparatus for Molten Fluorides 6.3.2 Volatilization of Iodine from the MSRE Fuel 6.4 Graphite Compatibility 6.4.1 Effect of Cesium Vapor on Graphite 6.5 Fuel Production 6.5.1 Purification Treatments 6.6 Analytical Chemistry 6.6.1 Analyses of MSRE Fuel Mixture 6.6.2 Analyses of MSRE Cover Gas

119 119 119 119 122 124

7. ENGINEERING RESEARCH 7.1 Physical-Property Measurements 7.2 Heat-Transfer Studies

131 131 133

8. FUEL PROCESSING 8.1 Preparation and Analysis of Complex Fluorides of SbF5 with KF, AgF, and SrF2 8.2 Preparation and Analysis of the NaF-MoF6 Complex 8.3 Preparation and Analysis of Complexes of UF6 with LiF, NaF, and KF 8.4 Attempt to Separate Rare Earth Fluorides from MSBR Blanket Salt by SbF5 in HF

135 135 135 136 136

124 125 126 126 126 127 127 128 128 128 128 129

ORNL-3282 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending February 28, 1962 SUMMARY

iii

PART I. MSRE DESIGN, COMPONENT DEVELOPMENT, AND ENGINEERING ANALYSIS 1. MSRE DESIGN 1.1 Introduction 1.2 Reactor Core and Vessel 1.3 Primary Heat Exchanger 1.4 Radiator 1.5 Fuel-Salt Drain Tanks 1.6 Equipment Layout 1.7 Cover-Gas System 1.8 System Heaters 1.9 Maintenance Design, Assembly Jigs, and Fixtures 1.10 Reactor Procurement and Installation 1.10.1 Major Modifications to Building 7503 1.10.2 Construction Outside Building 7503 1.10.3 Planning and Scheduling of the MSRE Installation 1.10.4 Procurement of Materials 1.10.5 Procurement of Components 1.11 Reactor Instrumentation and Controls System 1.11.1 Nuclear Control System 1.11.2 Instrument-Application Diagrams 1.11.3 Electrical Control Circuitry 1.11.4 Layout of Instrumentation and Controls System 1.11.5 Control Panels 1.11.6 Data Handling 1.11.7 Process and Personnel Radiation Monitoring 1.11.8 Procurement Status

1 1 2 3 4 4 4 6 6 7 7 7 9 9 9 10 10 10 14 15 15 17 18 18 19

2. COMPONENT DEVELOPMENT 2.1 Freeze-Flange Development 2.1.1 MSRE 5-in. Flanges 2.1.2 Freeze-Flange-Seal Test Facility 2.2 Control-Rod Development 2.3 Heater Tests 2.3.1 Pipe Heaters 2.3.2 Reactor Vessel Beaters 2.4 Drain-Tank Cooler 2.5 Sampler-Enricher System 2.5.1 General Concept of Sampler-Enricher 2.5.2 Operational Valve 2.5.3 Removal Seal for Sample Container 2.5.4 Detail Design of Sampler-Enricher 2.6 MSRE Core Development 2.6.1 Full-Scale Core Model 2.6.2 Core-Inlet: Flow Distribution 2.7 Helium Purification

21 21 21 21 24 26 26 29 29 29 29 31 31 32 32 32 32 33

2.8 MSRE Engineering Test Loop (ETL) 2.8.1 Loop Operations 2.8.2 Operation of Freeze Valve 2.8.3 Oxide Removal 2.8.4 HF Treatment 2.8.5 ETL Graphite Facility 2.9 MSRE Maintenance Development 2.9.1 Placement and Removal of Freeze-Flange Clamp 2.9.2 Flange Alignment and Pipe-Jacking Tools 2.9.3 Gasket-Replacement Procedures 2.9.4 Miscellaneous Disconnects 2.9.5 Remote Viewing 2.9.6 Component Removal 2.10 Brazed-Joint Development 2.10.1 Joint Design 2.10.2 Brazed-Joint Testing 2.10.3 Remote Fabrication of Braze Joint 2.11 Mechanical-Joint Development 2.12 Steam Generator 2.13 Pump Development 2.13.1 MSRE Fuel Pump 2.13.2 MSRE Coolant Pump 2.13.3 Advanced Molten-Salt Pumps 2.14 MSRE Instrument Development 2.14.1 Thermocouple Attachments 2.14.2 Temperature Scanner 2.14.3 Single-Point Temperature-Alarm System 2.14.4 Pump-Bowl Level Indicator 2.14.5 Single-Point Level Indicator 3. REACTOR ENGINEERING ANALYSIS 3.1 Reactor Physics 3.1.1 Analysis of MSRE Temperature Coefficient 3.1.2 Reactor-Kinetics Studies 3.1.3 Gamma-Heating Survey

34 35 35 37 37 37 41 41 41 41 43 43 44 45 45 45 46 51 51 51 52 55 56 58 58 58 60 61 66 68 68 68 69 70

PART II. MATERIALS STUDIES 4. METALLURGY 4.1 Dynamic-Corrosion Studies 4.1.1 Fluoride-Salt Contamination Studies 4.1.2 Molybdenum-Graphite Compatibility Tests 4.1.3 Corrosion Effects of Carbon Tetrafluoride 4.1.4 Examination of Corrosion Inserts from INOR-8 Forced-Convection Loops 4.2 Welding and Brazing Studies 4.2.1 Heat Exchanger Fabrication 4.2.2 Remote Brazing 4.2.3 Welding of INOR-8 4.2.4 Mechanical Properties of INOR-8-Dissimilar-Metal Welds 4.3 Mechanical Properties of INOR-8 4.4 Evaluation of MSRE Type Graphite 4.4.1 Comparison of the Permeation of Graphite by Mercury, and Molten Fluorides 4.4.2 Removal of Oxygen Contamination from Graphite with Thermal Decomposition Products of NH4F-HF 4.4.3 Reaction of ZrO2 with Thermal Decomposition Products of NH4F-HF

72 72 72 74 77 79 81 81 84 86 88 89 89 92 94 94

5. IN-PILE TESTS 5.1 Interaction of Fissioning Fuel with Graphite: Test No. ORNL-MTR-47-3 5.1.1 Description of Experiment 5.1.2 Dismantling of In-Pile Assembly 5.1.3 Temperatures 5.1.4 Gas Analyses 5.1.5 Test Effects on Graphite 5.1.6 Analyses of Graphite 5.1.7 Test Effects on Coupons 5.1.8 Test Effects on Fuel 5.1.9 Conclusions 5.2 MSRE In-Pile Testing

97 97 97 99 100 100 105 106 106 106 110 110

6. CHEMISTRY 6.1 Phase-Equilibrium Studies 6.1.1 The System LiF-BeF2-ZrF4 6.1.2 The System LiF-BeF2-ZrF4-ThF4-UF4 6.1.3 Phase Equilibrium Studies in Fluoride Systems 6.2 Oxide Behavior in Fuels 6.2.1 Removal of Oxide from a Flush Salt 6.2.2 The Behavior of Sulfates in Molten Fluorides 6.3 Physical and Chemical Properties of Molten Salts 6.4 Graphite Compatibility 6.4.1 The Behavior of Carbon Tetrafluoride in Molten Fluorides 6.5 Chemical Aspects of MSRE Safety 6.5.1 Physical Effects of Mixing Molten Fuel and Water 6.5.2 Solubility of Fuel-Salt Components in Water 6.5.3 Solubility of MSRE Coolant in Water 6.5.4 Partial Freezing of MSRE Fuel 6.6 Fluoride-Salt Production 6.6.1 Production Rates 6.7 Analytical Chemistry 6.7.1 Oxygen in Nonradioactive MSRE Fuel 6.7.2 Adaptation of Analytical Methods to Radioactive Fuel

114 114 114 116 116 117 117 118 121 122 122 124 124 127 129 130 130 130 131 131 132

7. FUEL PROCESSING 7.1 MSRE Flowsheet 7.2 Fluorine Disposal Tests, Using Charcoal

134 132 134

ORNL-3369 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending August 31, 1962 SUMMARY

iii

PART 1. MSRE DESIGN, ENGINEERING ANALYSIS, AND COMPONENT DEVELOPMENT 1. MSRE DESIGN Design Status Reactor Procurement and Installation Major Modifications to Building 7503 Construction Outside Building 7503 Procurement of Materials Fabrication of Components Reactor Instrumentation and Control Systems Layout of Instrumentation and Control System Design Status Procurement Status

3 3 4 4 7 7 8 14 14 14 16

2. MSRE REACTOR ANALYSIS Nuclear Accident Analyses Calculational Procedures Results of Fuel Pump Power Failure Analysis Effects of Cold-Slug Accidents Results for Filling Accidents Effect of Uncontrolled Withdrawal of Rods Effect of Graphite Movement Results of Concentrated Fuel Addition Reactor Statics Calculations Criticality Calculations Flux Distributions Power Density Steady-State Fuel and Graphite Temperatures Temperature Distributions Average Temperatures Reactivity Coefficients Temperature Coefficients Power Coefficient Effective Delayed-Neutron Fractions Reactor Kinetics Code Development

17 17 17 17 19 21 21 21 22 22 24 24 24 27 27 29 33 33 34 35 37

3. COMPONENT DEVELOPMENT Freeze-Flange Development Freeze-Flange-Seal Test Thermal-Cycle Test Loop Freeze Test in Thermal-Cycle Test Loop Test of a Freeze Flange in the Prototype-Fuel-Pump Testing Facility MSRE Control Rod Heater Tests Pipe Heaters

41 41 41 43 46 46 46 46 46

Activation Analysis of Insulating Materials Drain-Tank Coolers Sampling and Enriching System Detail Design Mockup of Sampling and Enriching System Core Development Model Operations Velocity Measurements Measurement of Heat Transfer Coefficients Experiments on the Behavior of Solids MSRE Engineering Test Loop (ETL) Frozen-Salt-Sealed Graphite-Container Access Joint Salt Composition HF Treatment Cold-Finger Collections in Cover Gas ETL Graphite Treatment MSRE Maintenance Placement and Removal of Freeze-Flange Clamps Miscellaneous Flange-Servicing Tools Remote Viewing Portable Maintenance Shield Brazed-Joint Development Brazed-Joint Fabrication Brazed-Joint Salt Test Mechanical-Joint Development Pump Development Fuel Pump Design and Fabrication Coolant Pump Design and Fabrication Design and Fabrication of Lubrication Stands for Pumps Lubrication-Pump Endurance Test Drive Motor Design and Fabrication Test Pump Fabrication Test Facility Construction Hydraulic Performance Tests PKP Pump Hot Endurance Test Test Pump With One Molten-Salt-Lubricated Bearing Instrument Development Single-Point Liquid-Level Indicator Pump-Bowl Liquid-Level Indication Single-Point Temperature Alarm System Temperature Scanner Thermocouple Development and Testing

47 49 49 49 49 49 49 50 51 52 53 53 54 56 56 58 59 59 60 60 60 61 61 62 62 62 62 62 63 63 63 63 63 65 66 66 66 66 68 68 71 74

PART 2. MATERIALS STUDIES 4. METALLURGY Corrosion Effects of CF4 Welding and Brazing Studios Heat Exchanger Fabrication Remote Brazing Welding of INOR-8 Mechanical Properties of INOR-8 Properties of Reactor-Quality INOR-8 Thermal Fatigue of INOR-8

87 87 88 88 92 92 95 95 95

Graphite Studies Evaluation of Grade TS-281 Graphite Effects of Thermal Decomposition Products of NH4F-HF on Graphite-INOR-8 Systems Fabrication of Gd2O3 and Gd2O3-Al2O3 Pellets

96 96 97 98

5. IN-PILE TESTS ORNL-MTR-47 Molten-Salt Irradiation Experiments Experiment ORNL-MTR-47-4 Experiment ORNL-MTR-47-5 Post-Irradiation Examination of Experimental Assembly ORNL-MTR-47-3 Chemical Analyses of Irradiated Fuel for Corrosion Products Distribution of Radioactivity and Salt in Irradiated Graphite Post-Irradiation Examination of Experimental Assembly ORNL-MTR-47-4 Description of Capsule Fabrication and Loading of Capsules Fuel Graphite Decay Energy Irradiation and Temperature Data Production of Xenon and Krypton Gas Analyses Discussion of Results

100 100 100 102 105 105 106 106 108 108 109 109 110 110 110 112 115

6. CHEMISTRY Phase Equilibrium Studies The System LiF-BeF2-ZrF4 The System LiF-BeF2-ZrF4-ThF4-UF4 LiF-UF4 Eutectic as a Concentrated Solution of UF4 for Fuel Makeup Fractionation of LiF-BeF2-ZrF4-ThF4-UF4 on Freezing Crystal Chemistry Oxide Behavior in Molten Fluorides -Dehydration of LiF Physical Properties of Molten Salts Density of LiF-BeF2-ZrF4-UF4 Estimation of Densities of Molten Fluorides Graphite Compatibility Removal of Oxide from Graphite Moderator Elements Behavior of CF4 in Molten Fluorides Analytical Chemistry Determination of Oxygen in MSRE Fuel Mixtures Determination of Oxygen in Graphite Homogenization of Radioactive MSRE Fuel Samples

117 117 117 118 119 121 121 122 123 123 123 125 125 128 130 130 131 131

7. FUEL PROCESSING

133

8. ENGINEERING RESEARCH ON THERMOPHYSICAL PROPERTIES OF SALT MIXTURES Enthalpy Viscosity

135 135 136

ORNL-3419 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending January 31, 1963 SUMMARY

iii

PART 1. MSRE DESIGN, ENGINEERING ANALYSIS, AND COMPONENT DEVELOPMENT 1. REACTOR ANALYSIS Analysis of Filling Accident Coolant Salt Activation Reactivity Effects of 135Xe Reactivity Effects of Changes in Salt and Graphite Densities

3 3 4 4 6

2. COMPONENT DEVELOPMENT Freeze-Flange Joint Development Thermal-Cycling Test Joint Tests in Pump-Testing Facility Tests of Freeze-Valve Control Circuit Transfer Valve Reactor Drain Valve Reactor Control Rods and Drives Control Rod Drive Prototype Control Rod Heater Tests Pipe Heaters with Reflective Insulation Drain Tank Coolers Sampler-Enricher System Mockup Flange Disconnects Core Development Internal Flow Distribution Core Pressure Drop Engineering Test Loop (ETL) Results of the Graphite Pretreatment Loop Operation Operation of the Graphite Container Access Joint Graphite Sampling Via Removable Dry Box Analysis of Solids Removed from the Graphite Container Access Joint Chemical Analysis and HF Treatment of ETL Flush Salt ETL Graphite Permeability Xenon Transport in the MSRE MSRE Maintenance Development Maintenance Study Model Pump Development Prototype Pump Operation and Testing PKP Fuel Pump High-Temperature Endurance Test Lubrication-Pump Endurance Test Instrument Development Single-Point Liquid-Level Indicator Pump-Bowl Liquid-Level Indicator Bubbler-Type Liquid-Level Indicator

10 10 10 12 12 14 15 15 17 17 17 23 23 27 27 27 28 28 29 30 30 32 33 33 35 35 35 37 37 37 40 40 40 40 41 43

Temperature Scanner High-Temperature NaK-Filled Differential-Pressure Transmitter Thermocouple Development and Testing 3. MSRE DESIGN Design Status Reactor System Instrumentation and Controls Procurement and Installation Status Subcontract Work at Reactor Site Fabrication of Major Reactor Components MSRE Cost Estimate Revision

44 45 46 49 49 49 49 54 54 54 62

PART 2. MATERIALS STUDIES 4. METALLURGY Heat Exchanger Fabrication Sample Tube Bundle Tube Joint Inspection MSRE Tube Bundle Mechanical Properties of INOR-8 ASME Boiler and Pressure Vessel Code Allowable Stresses for INOR-8 Reactor-Quality INOR-8 Evaluation of MSRE Graphite Salt Permeation of MSRE Graphite Thermal Cycling of Salt-Impregnated Graphite Tensile Strength of CGB Graphite Development of Gd2O3-Al2O3 Control Rod Elements Sample Control Rod Element Testing Sintering Characteristics of Gd2O3-Al2O3 Specimens

65 65 65 65 67 68 68 68 70 71 71 74 76 76 76

5. RADIATION EFFECTS Postirradiation Examination of Experimental Assembly ORNL-MTR-47-3 Postirradiation Examination of Experimental Assembly ORNL-MTR-47-4 Gas Analyses Metallographic Evaluation of the Wall of a Capsule from Experimental Assembly ORNL-MTR-47-4 Autoradiography of Unopened Capsules Bubble Formation in Capsules Chemical Analyses of Materials from Experimental Assembly ORNL-MTR-47-4 Observations of Sectioned Capsules Control Experiments on the Fluorination of Graphite Conclusions Drawn from the ORNL-MTR-47-4 Experiment Molten-Salt Irradiation Experiment ORNL-MTR-47-5 Capsule Irradiation and Sampling Analyses of Gas Samples Taken During Irradiation Pressure Increase During Reactor Shutdown Effects of Fissioning in Frozen Fuel Pressure Rise Following Termination of Exposure Conclusions Drawn from Experiment ORNL-MTR-47-5

80 80 80 80

6. CHEMISTRY Phase Equilibrium Studies The System LiF-ZrF4-UF4 The System UF3-UF4

108 108 108 108

84 87 88 88 91 93 93 94 94 97 101 104 106 106

The System LiF-UF3-UF4 109 The System LiF-BeF2-UF3 109 The System LiF-BeF2-ZrF4-UF3 109 Core and Blanket Fluids for Future Reactors 109 Crystal Structure of Xenon Fluoride 110 Oxide Behavior in Mixtures of Flush Salt and Fuel Salt 110 Physical Properties of Molten Fluorides 116 Vapor Pressures of Fluoride Mixtures 116 Densification of LiF Powder 117 Density of CrF2 119 Activity Coefficients of ZrF4 in the LiF-ZrF4 System 120 Graphite Investigations 122 Evolution of Volatile Impurities from Graphite 122 Behavior of Carbon Tetrafluoride in Molten Fluorides 127 Production of Purified Materials 131 Pure Uranium Trifluoride 131 Preparation of Xenon Tetrafluoride 131 Fluorine Gas Manifold 133 Out-of-Pile Irradiation Studies 134 Fluorine Evolution from Solid Fluoride Salts Under Irradiation by VanDeGraaf Electrons 134 Effect of Beta Radiation on Fused Fluorides 135 Gamma Irradiation Experiments with a 10,000-Curie Cobalt-60 Source 135 X-ray Irradiation of Inorganic Fluorides 136 Reaction of Fluorine with Reduced Fuel 136 Analytical Chemistry 138 Methods for the Analysis of Radioactive MSRE Fuel 138 Analytical Hot-Cell Mockup for MSRE Fuel Analysis 140 7. FUEL PROCESSING

141

ORNL-3529 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending July 31, 1963 SUMMARY

iii

Part 1. MSRE DESIGN, ENGINEERING ANALYSIS, AND COMPONENT DEVELOPMENT 1. MSRE DESIGN, PROCUREMENT, AND CONSTRUCTION Status of Design Mechanical and Process Design Instrumentation and Control Design Status of Fabrication of Major Reactor Components Reactor Vessel and Control Rod Thimble Assembly Heat Exchanger Fuel and Coolant Pumps Radiator and Radiator Enclosure Salt Storage Tanks Freeze Flanges Major Procurement Moderator Graphite Salt Piping and Component Heating Equipment Remote Maintenance Equipment Reactor Auxiliary Systems Instrumentation Fabrication Fuel-Salt Sampler and Enricher Status of Construction Reactor Cell Fuel-Drain-Tank Cell Coolant Cell CPFF Construction Procurement and Installation of Instrumentation

3 3 3 5 9 9 9 9 9 9 15 15 15 15 15 15 15 16 16 16 16 16 21 21

2. COMPONENT DEVELOPMENT Drain-Tank Cooler Test Heater Tests Drain-Tank Heater Pipe Heater with Reflective Insulation Control Rod Control Rod Prototype Helium Purification System Sampler-Enricher System Mockup Flange Disconnects Operational and Maintenance Valves Design Engineering Test Loop Treatment of Flush Salt with HF in ETL Drain Tank Following Oxide Additions Treatment of Fuel Salt with HF in ETL Drain Tank Loop Operation with Fuel Salt and Graphite Operation of the Graphite Container Access Joint Analysis for Chromium as an Indication of Corrosion

23 23 23 23 30 30 34 34 35 37 38 38 38 38 38 40 40 41

Xenon Transport in MSRE System Prototype Pump Testing Facility Water Test Pump Loop Maintenance Development Pump Development Prototype Pump Operation and Testing PKP Fuel Pump High-Temperature Endurance Test Test Pump with One Molten-Salt-Lubricated Bearing Lubrication-Pump Endurance Test Fuel Pump MK-2 Instrument Development Single-Point Liquid-Level Indicator Pump-Bowl Liquid-Level Indicator Temperature Scanner Thermocouple Development and Testing Closed-Circuit Television for Remote Maintenance Viewing High-Temperature NaK-Filled Differential Pressure Transmitter Bubbler-Type Liquid-Level Indicator 3. MSRE REACTOR ANALYSIS Nuclear Characteristics of Core Control Rod Worth Method of Calculation Results Reactivity Shimming Inherent Neutron Sources Biological Shielding

44 44 44 45 47 47 52 54 54 54 54 54 55 55 56 57 57 58 60 60 62 62 62 64 66 66

Part 2. MATERIALS STUDIES 4. METALLURGY Heat Exchanger Fabrication MSRE Primary Heat Exchanger Brazing Ultrasonic Inspection of Tube Joint Brazing Mechanical Properties of INOR-8 Thermal Fatigue Postirradiation Tensile Testing Evaluation of MSRE Graphite Chemical Composition and Oxygen Content Thermal Cycling of Salt-Impregnated Graphite Irradiation Effects on Grade CGB Graphite Removal of Oxygen from Graphite with Molten Salts Sintering Characteristics of Gd2O3-Al2O3

71 71 71 71 73 73 75 75 75 76 76 77 78

5. RADIATION EFFECTS Postirradiation Examination of Assembly ORNL-MTR-47-4 Xenon Recovery from Graphite Cores Nonvolatile Constituents in Graphite Cores Effect of Irradiation in Assembly ORNL-MTR-47-5 Production of CF4 Under Operating Conditions Postirradiation Examination of Assembly ORNL-MTR-47-5 Fluorine Generation from Decay Energy Out-of-Pile Irradiations of Solid MSRE Salts Gamma Irradiations X-Ray Irradiations

80 80 80 81 83 83 86 86 94 94 96

Irradiation with Van de Graaff Electrons Irradiation of CF4

98 103

6. CHEMISTRY Phase Equilibrium Studies Phase Behavior in MSRE Fluoride Systems Liquid Immiscibility in the System LiF-BeF2-ZrF4 Petrographic Examination of Irradiated MSRE Salt Xenon Fluoride Studies Core and Blanket Fluids for Future Reactors Oxygen and Sulfur in Molten Fluorides Oxide Behavior in Li2BeF4-ZrF4-UF4 Removal of Sulfates from Li2BeF4 Physical Properties of Molten Fluorides Interfacial Behavior of Molten Fluorides with Graphite Viscosities of MSRE Fuel and Coolant Oxidation-Reduction Reactions in MSRE Melts Chemical Reduction of Dissolved Fluorides of Structural Metals Apparent Solubility of UF3 Produced by Reducing Fuel with Excess Zirconium Metal Development and Evaluation of Methods for the Analysis of the Radioactive MSRE Fuel Fluoride Chromium Oxygen Nickel Development and Testing of Equipment in the Hot-Cell Mockup

105 105 105 106 108 110 110 111 111 117 125 125 129 130 130 134 135 136 136 136 137 138

7. FUEL PROCESSING

141

ORNL-3626 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending January 31, 1964 SUMMARY

iii

INTRODUCTION

1

Part 1. MSRE DESIGN, ENGINEERING ANALYSIS, AND COMPONENT DEVELOPMENT 1. MSRE DESIGN, PROCUREMENT, AND CONSTRUCTION Status of Design Mechanical and Process Design Instrumentation and Controls Design Status of Fabrication of Major Reactor Components Reactor Vessel and Control Rod Thimble Assembly Fuel and Coolant Pumps Radiator and Radiator Enclosure Salt Storage Tanks Freeze Flanges Major Procurement Salt Piping and Component Heating Equipment Remote Maintenance Equipment Reactor Auxiliary Systems Neutron Instrument Tube Instrumentation Status of Construction Reactor Cell Fuel Drain Tank Cell Coolant Drain Cell Radiator Cell and Penthouse Auxiliaries Leak Testing General Instrumentation Cost Plus Fixed Fee Construction Mechanical Electrical

5 5 5 6 9 9 9 11 11 11 14 14 14 14 14 14 15 15 17 17 17 17 17 19 19 19 19

2. COMPONENT DEVELOPMENT Primary Heat Drain Tank Heater Pipe Heaters Drain Tank Cooler Modified Freeze Valves Reactor Drain Valve Control Rod Test Helium Purification System Engineering Test Loop Mockup of Sampler-Enricher System Sample Capsule

23 23 23 24 24 27 27 29 31 32 32 32

Enriching Capsule Sample Transport Container Manipulator Valves Design Maintenance Development Television Viewing Maintenance Shield Long-Handled Tools Plans and Procedures Pump Development Prototype Pump Operation and Testing Rotary Assemblies for the MSRE Fuel- and Coolant-Salt Pumps Test Pump with One Molten-Salt-Lubricated Bearing PKP Fuel-Pump High-Temperature Endurance Test Lubrication-Pump Endurance Test MK-2 Fuel Pump MSRE Pump Fabrication Instrument Development High-Temperature NaK-Filled Differential-Pressure Transmitter Thermocouple Development and Testing Thermocouple Test Assembly for Temperature Safety Channel Temperature Alarm Switches Marker Generator for Temperature Scanner Bubbler-Type Molten-Salt-Level Indicator Float-Type Molten-Salt-Level Transmitter Single-Point Level Indicator Positive-Position Indicator for MSRE Control Rod Pressure-Transmitter Expansion Chamber Assembly 3. MSRE REACTOR ANALYSIS Nuclear Analysis Report Flux Distributions from an External Neutron Source Criticality in Drain and Storage Tanks Shutdown to Ambient Temperature with Fuel in the Core Computational Methods - Revisions in Cross Sections and Group Structure Prompt Temperature Coefficient in a Large Molten-Salt Converter Reactor

34 34 34 34 34 35 35 35 35 37 37 37 40 40 40 41 41 41 41 41 42 44 45 45 45 46 46 47 48 51 51 51 51 53 53 54

Part 2. MATERIALS STUDIES 4. METALLURGY Mechanical Properties of INOR-8 Stress Rupture Strength Thermal Fatigue Mechanical Properties of INOR-8 Irradiated at Elevated Temperatures Evaluation of MSRE Graphite Structure of Grade CGB Graphite Gas Evolution Lattice Constants Structural Integrity of Retainer Ring and Lattice Bars Thermal Conductivity of Grade CGB Graphite Effect of Irradiation on Grade CGB Graphite Manufacture of MSRE Control Rod Elements

61 61 61 61 63 67 67 69 70 70 71 72 76

5. RADIATION CHEMISTRY OF THE MSRE SYSTEM Experiment ORNL-MTR-47-3: Examination of INOR-8,Molybdenum, and Pyrolytic-Carbon Specimens Postirradiation Examination of Assembly ORNL-MTR-47-4 Nonvolatile Constituents in Graphite Metallographic Examination of the Graphite Implications of Uranium Deposition for the MSRE Postirradiation Examination of Assembly ORNL-MTR-47-5 Fluorine Evolution from Capsules 3 and 4 During Reactor Shutdowns Analysis of Gas from Sealed Capsules Visual and Photographic Examination of Capsules Preliminary Examination of the Fuel Neutron-Flux Determinations Plans for In-Pile Experiment ORNL-MTR-47-6 Gamma Irradiation of a Simulated MSRE Fuel Salt in the Solid Phase Experimental Discussion Fluorine Evolution from Solid Fluoride Salts Under Irradiation by VanDeGraaff Electrons Experimental Results Discussion Effect of Soft X-Rays on Solid Fluorides

79

6. CHEMISTRY Phase Equilibrium and Solubility Studies Among Fluorides The System LiF-BeF2-ZrF4 Crystallization of the MSRE Fuel Solubility of Uranium Trifluoride in a Reduced MSRE Fuel-Salt Mixture Stability of Uranium Trifluoride in Molten Fluoride Solvents Crystal Structure of 6LiF-BeF2-ZrF4 Core and Blanket Fluids for Future Reactors Chlorides as Fast Reactor Fuels Fluoride Salts for Use as Blanket Fluids: The System NaF-KF-ThF4 Phase Separation of Molten Halides and Lead Removal of Moisture from MSR Graphite Interfacial Behavior of Fluorides with Graphite and Metals Graphite Metals HF-H2O Equilibria with Molten Fluorides Removal of Sulfates from 2LiF-BeF2 Fluoride Salt Production Production Process Raw-Material Procurement LiF Densification Development and Evaluation of Methods for the Analysis of the MSRE Fuel Electrochemical Analyses Oxidation States – Uranium Methods Development Mockup of Hot Cell

114 114 114 117 117 119 120 123 123 125 126 127 132 132 135 137 141 146 147 149 149 151 151 153 154 155

7. FUEL PROCESSING

161

79 81 82 85 85 86 86 87 91 97 98 98 101 101 104 105 105 106 108 110

ORNL-3708 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending July 31, 1964 INTRODUCTION

1

THE PLACE OF MOLTEN-SALT REACTORS IN THE AEC PROGRAM E.E. Sinclair

1

MOLTEN-SALT POWER REACTORS AND THE ROLE OF THE MSRE IN THEIR DEVELOPMENT R.B. Briggs 3 MSRE DESIGN AND CONSTRUCTION W.B. McDonald

22

NUCLEAR CHARACTERISTICS OF THE MSRE R.J. Engel

83

INSTRUMENTATION AND CONTROL OF THE MSRE J.R. Tallackson

115

PUMP DEVELOPMENT A.G. Grindell and P.G. Smith

147

COMPONENT DEVELOPMENT IN SUPPORT OF THE MSRE Dunlap Scott, Jr

167

REMOTE MAINTENANCE OF THE MSRE - Robert Blumberg

190

FUEL PROCESSING FACILITY- R.B. Lindauer

201

PLANS FOR OPERATION OF THE MSRE - P.N. Haubenreich

205

CHEMICAL BASIS FOR MOLTEN-SALT REACTORS W.R. Grimes

214

EFFECTS OF RADIATION ON THE COMPATIBILITY OF MSRE MATERIALS F. F. Blankenship

252

PREPARATION OF MSRE FUEL, COOLANT, AND FLUSH SALTS - J.H. Shaffer

288

FUTURE CHEMICAL DEVELOPMENT - H.F. McDuffie

304

ANALYTICAL CHEMISTRY FOR THE MOLTEN-SALT REACTOR - J.C. White

320

METALLURGICAL DEVELOPMENTS - A. Taboada

330

MSRE GRAPHITE - W.H. Cook

373

ORNL-3812 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending February 28, 1965 SUMMARY

iii

INTRODUCTION

1 Part 1. MSRE OPERATIONS AND CONSTRUCTION, ENGINEERING ANALYSIS, AND COMPONENT DEVELOPMENT

1. MSRE OPERATIONS Chronological Account Component and System Performance Heaters and Insulation Freeze Flanges Freeze Valves Reactor Access Nozzle Fuel and Coolant Pumps Radiator Weighing Systems Drain Tank Heat Removal Systems Thermal Shield Cooling Water Helium and Off-Gas Systems Operations Analysis Behavior of Noble Gas in the Fuel System Gas in Circulating Loops Overflow from Fuel Pump Fuel and Coolant Pump Cool-Down Rates Drying Out the Salt Systems Instrumentation and Controls Design and Installation General Reactor Process Instrumentation Reactor Nuclear Instrumentation Electrical Control Circuits Control Panels and Cabinets Data System Fuel Sampler-Enricher and Chemical Processing System Sampler Coolant Salt Sampler Personnel and Stack Monitors Reliable Instrument Power System Remote-Maintenance Closed-Circuit Television MSRE Component Fabrication Sampling and Enriching Systems Vapor-Condensing System MSRE Construction and Installation Pump Installation Heat Exchanger Modification and Installation Heater and Electrical Installation High-Bay Containment

5 5 6 6 7 8 9 9 10 10 11 11 11 12 12 14 14 15 15 17 17 17 18 18 19 22 22 22 23 23 23 24 24 25 25 25 25 26 26

Drain Tank System Charcoal Beds Control Rod Drives Sampling and Enriching Systems Vapor-Condensing System

26 26 26 26 26

2. COMPONENT DEVELOPMENT Life Tests Pipe Heaters Drain Tank Heater Drain Tank Cooler Freeze Valve Check-Out and Startup of Components Freeze Flanges Freeze Valves Control Rods Prototype Control Rod Drive Test Control Rod Drive Units Diaphragm Leakage Samplers Temporary Drain Tank Sampler Temporary Fuel System Sampler Coolant Salt System Sampler Engineering Test Loop Zirconium Oxide Cold Trap Maintenance Instrument Development Ultrasonic Single-Point Molten-Salt Level Probe Float-Type Molten-Salt Level Transmitters Conductivity-Type Single-Point Molten-Salt Level Probe MSRE Bubbler-Type Molten-Salt Level Indicator Thermocouple Development and Testing Temperature Scanner Single-Point Temperature Alarm Switches High-Temperature Resistance Thermometers High-Temperature NaK-Filled Differential Pressure Transmitter Helium Control Valve Trim Replacement Control Valve Actuator Motion Multiplier Pump Development MSRE Pumps Other Molten-Salt Pumps

27 27 27 27 27 28 28 28 28 29 29 30 31 32 32 32 32 35 35 36 38 38 41 41 42 43 44 46 47 48 48 49 50 50 52

3. MSRE REACTOR ANALYSIS MSRE Stability Analysis Methods Used Results Suppression of Criticality in MSRE Cell in Event of the Maximum Credible Accident Effectiveness of a Radial Molten-Salt Blanket on the Breeding Potential of a One-Fluid Graphite-Moderated Reactor Results

54 54 54 54 56 57 57

Part 2. MATERIALS STUDIES 4. METALLURGY Reaction of INOR-8 with Impure Nitrogen Alteration of MSRE Heat Exchanger Tube Bundle INOR-8 Welding Studies Mechanical Properties of INOR-8 Weld Metal INOR-8 Welding Microstructure Study Graphite-to-Metal Joining Development Transition Joints Brazing Alloy Development Evaluation of MSRE Graphite Oxygen Contamination of the MSRE Core Bars and Lattice Bars Accessible Voids Content of MSRE Core Graphite Metallographic Examination of Bayonet Tube in Drain Tank Cooler Test Mechanical Properties of Irradiated INOR-8 MSRE Materials Surveillance Testing Control Test for Surveillance Specimen

63 63 64 67 67 71 73 73 75 76 76 77 80 82 83 84

5. RADIATION CHEMISTRY Introduction Experiment MTR-47-5 Graphite INOR-8 Fuel Salt Summary of MTR-47-5 Postirradiation Examinations Experiment MTR-47-6 Objectives Experimental Results and Discussion Summary of Experiment MTR-47-6

87 87 87 89 97 99 102 102 102 103 107 119

6. CHEMISTRY High-Temperature Fluoride Phase Equilibrium Studies Fuel System for the Molten-Salt Reactor Experiment Reactions in Molten Salt Systems HF-H2O Equilibrium with Molten Fluorides Advantages of On-Stream HF-H2 Sparging of MSR Fuels The Stability of UF3 Viscosity in the LiF-BeF2 System Fuel, Coolant, and Flush Salts for the MSRE The Production Process Coolant and Flush Salt Mixtures Component Mixtures for the MSRE Fuel Chemistry of Pre-nuclear Use of Fuel and Flushing Salts in the MSRE Compositional Analysis of MSRE Salts Chemical Analyses of Fuel and Circuit Salts During Pre-nuclear Tests of the MSRE Development and Evaluation of Equipment for Analyzing Radioactive MSRE Fuel Samples Sample Preparation Sample Analyses Development and Evaluation of Methods for the Analysis of the MSRE Fuel Oxide Reducing Power Electrochemical Analyses

121 121 121 129 129 136 138 144 146 147 147 148 150 150 152 155 155 156 160 160 163 164

7. FUEL PROCESSING MSRE Fuel Processing System Status Water Monitor Chromium Fluoride Trapping

169 169 170 171

ORNL-3872 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending August 31, 1965 SUMMARY

vii

INTRODUCTION

1 Part 1. MSRE OPERATIONS AND CONSTRUCTION, ENGINEERING ANALYSIS, AND COMPONENT DEVELOPMENT

1. MSRE OPERATIONS Chronological Account Component and System Performance Control Rods Sampler-Enricher Freeze Valves Freeze Flanges Fuel and Coolant System Pressure Control Heaters and Insulation Reliable Instrument Power System Thermal-Shield Cooling Water Fuel-Pump Overflow Tank Analysis of Operation Basic Nuclear Characteristics Dynamic Tests Undissolved Gas in Fuel Loop Salt Density and Inventory Experience External Neutron Source Instrumentation and Controls Design and Installation General Design, Installation, and Checkout Instrumentation and Controls System Performance Revisions and Modifications Documentation

7 7 10 10 11 12 13 13 15 15 16 16 16 16 24 30 30 31 32 32 32 40 43 46

2. COMPONENT DEVELOPMENT Life Tests Freeze Valve Pipe Heater Drain-Tank Heater Checkout and Startup of Components Control Rods Control Rod Drive Units Freeze Valves Freeze Valves 204 and 206 Freeze Valve 103 Freeze Valves 104, 105, and 106 Noble-Gas Dynamics Sampler-Enricher Removal Valve and Seal

48 48 48 48 48 48 48 49 51 51 51 53 55 56 56

Manipulator Access Port Operational Valve Sampling Capsule Fuel-Processing Sampler Off-Gas System Remote Maintenance Pump Development MSRE Pumps Measurement of the Concentration of Undissolved Helium in Circulating Molten Salt Other Molten-Salt Pumps Instrument Development Ultrasonic, Single-Point Molten-Salt Level Probe High-Temperature NaK-Filled Differential-Pressure Transmitter Float-Type Molten-Salt Level Transmitter Conductivity-Type, Single-Point Molten-Salt Level Probe Single-Point Temperature Alarm Switches Helium Control Valve Trim Replacement Thermocouple Development and Testing 3. MSRE REACTOR ANALYSIS Theory of Period Measurements Made with the MSRE During Fuel Circulation

56 57 57 58 58 58 60 61 61 62 65 66 66 70 71 71 72 72 73 75 75

Part 2. MATERIALS STUDIES 4. METALLURGY Dynamic Corrosion Studies Corrosion Studies Using Lead as a Coolant Revised Thermal Convection Loop Design MSRE Materials Surveillance Testing INOR-8 Surveillance Specimens Graphite Surveillance Specimens Assembly of Surveillance Specimens Evaluation of Radiation-Damage Problems of Graphite for Advanced Molten-Salt Reactors Mechanical Properties of Irradiated INOR-8 Mechanical Properties of Unirradiated INOR-8 Used in the Reactor Vessel Postirradiation Stress-Rupture Properties of INOR-8 In-Reactor Creep Tests

81 81 82 85 87 88 88 90 93 94 94 102 104

5. RADIATION CHEMISTRY Introduction Experimental Objectives and Design Considerations Experiment Design and Mockup Test Operation

106 106 106 107

6. CHEMISTRY Chemistry of the MSRE MSRE Fuel Loading MSRE Salt Chemistry During Pre-critical and Zero-Power Experiments Examination of Salts After the Zero-Power Experiment Density of MSRE Fuel and Coolant Salts Chemistry of LiF-BeF2 Systems Solubility of HF and DF in Molten LiF-BeF2 (66-34 Mole%) Vapor Pressure The Quest for Liquid-Liquid Immiscibility in LiF-BeF2 Melts Removal of Iodide from LiF-BeF2 Melts by HF-H2 Sparging

111 111 111 112 117 119 123 123 123 126 127

Salt Compositions for Use in Advanced Reactor Systems Blanket Salt Mixtures for Molten-Salt Breeder Reactors Coolants for the Molten-Salt Breeder Reactor Viscosity of NaBF4 Fuel and Blanket Materials for the Proposed MOSEL Reactor Recovery of Protactinium from Fluoride Breeder Blanket Mixtures Introduction Facility Description Oxide Precipitation of Protactinium Development and Evaluation of Methods for the Analysis of MSRE Fuel Determination of Oxide in MSRE Fuel Electrochemical Analysis Spectrophotometric Studies of Molten-Salt Reactor Fuels Analysis of MSRE Blanket Gas Development and Evaluation of Equipment for Analyzing Radioactive MSRE Fuel Samples Sample Preparation Sample Analyses Quality Control Program 7. FUEL PROCESSING

133 133 135 136 137 137 137 137 140 140 140 143 145 147 148 148 148 148 152

ORNL-3936 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending February 28, 1966 SUMMARY

vii

INTRODUCTION

1 Part 1. MSRE OPERATIONS AND CONSTRUCTION, ENGINEERING ANALYSIS, AND COMPONENT DEVELOPMENT

1. MSRE OPERATIONS Chronological Account Analysis of Experiments Reactivity Balance Power Calibration Flux Measurements MSRE Dynamic Tests Description of Dynamic Tests Frequency Response Tests Implementation of Pseudorandom Binary Tests Analysis Procedures Results Temperature Response Test Systems Performance Off-Gas System Salt-Pump Oil Systems Treated Cooling-Water System Secondary Containment Shielding Component Performance Radiator Other Components Inspection of the Fuel Pump Heat Treatment of Reactor Vessel Stress Analysis of Reactor Piping and Nozzles Instrumentation and Controls General Safety Instrumentation Wide-Range Counting Channels Nuclear Instrument Penetration BF3 Confidence Instrumentation Personnel Monitoring System Control Instrumentation Operating Experience - Process and Nuclear Instruments Data System MSRE Training Simulators Documentation

7 7 10 10 12 12 13 13 15 16 17 18 22 23 23 27 28 29 34 34 34 36 38 39 40 41 41 41 42 42 44 45 46 47 49 50 51

2. COMPONENT DEVELOPMENT Freeze Valves Control Rods Control Rod Drive Units Radiator Doors Radiator Heater Electrical Insulation Failure Sampler-Enricher Coolant Salt Sampler Examination of Components from the MSRE Off-Gas System Capillary Flow Restrictor FE 521 Check Valve CV 533 Charcoal Bed Inlet Valve HV 621 Line 522 Pressure Control Valve PCV 522 Line Filter 522 Flow Test on the MSRE Filter from Line 522 Fuel Processing System Sampler Off-Gas Sampler Xenon Migration in the MSRE Remote Maintenance Practice Before Operation Maintenance of Radioactive Systems Pump Development MSRE Pumps Other Molten-Salt Pumps Instrument Development Ultrasonic Single-Point Molten-Salt Level Probe High-Temperature NaK-Filled Differential-Pressure Transmitter Float-Type Molten-Salt Level Transmitter Conductivity-Type Single-Point Molten-Salt Level Probe Single-Point Temperature Alarm Switches Helium Control Valve Trim Replacement Thermocouple Development and Testing Temperature Scanner

53 53 53 54 54 57 58 59 60 60 60 60 62 64 65 65 67 69 70 72 72 74 74 75 77 77 77 78 78 78 79 79 80

3. MSRE REACTOR ANALYSIS Least-Squares Formula for Control Rod Reactivity Spatial Distribution of 135Xe Poisoning in MSRE Graphite

82 82 87

Part 2. MATERIALS STUDIES 4. METALLURGY Dynamic Corrosion Studies MSRE Material Surveillance Tests Reactor Surveillance Specimens Surveillance Control Specimens Hot-Cell Metallographic Examination of Hastelloy N from Experiment MTR-47-6 for Evidence of Nitriding Postirradiation Metallographic Examination of Capsules 1-4 from Experiment ORNL MTR-47-6 Development of Graphite-to-Metal Joints Tests of Graphite-Molybdenum Brazed Joint for Containing Molten Salts Under Pressure New Grades of Graphite Evaluation of the Effects of Irradiation on Graphite Effects of Irradiation on Hastelloy N Weld Studies on Hastelloy N

95 95 96 96 99 100 101 101 104 107 108 111 115

5. CHEMISTRY Chemistry of the MSRE Analyses of Flush, Fuel, and Coolant Salts Examination of Materials from the MSRE Off-Gas System Uranium-Bearing Crystals in Frozen Fuel Physical Chemistry of Fluoride Melts Vapor Pressure of Fluoride Melts Methods for Predicting Density, Specific Heat, and Thermal Conductivity in Molten Fluorides Oxide Solubilities in MSRE Flush Salt, Fuel Salt, and Their Mixtures Separations in Molten Fluorides Evaporative-Distillation Studies on Molten-Salt Fuel Components Effective Activity Coefficients by Evaporative Distillation Extraction of Rare Earths from Molten Fluorides into Molten Metals Removal of Protactinium Radiation Chemistry In-Pile Molten-Salt Irradiation Experiment Development and Evaluation of Methods for the Analysis of the MSRE Fuel Determination of Oxide in MSRE Fuel Voltammetric Determination of Ionic Iron and Nickel in Molten MSRE Fuel Development and Evaluation of Equipment and Procedures for Analyzing Radioactive MSRE Salt Samples Sample Analyses Quality Control Program

122 122 122 124 128 128 128

6. MOLTEN-SALT BREEDER REACTOR DESIGN STUDIES MSBR Plant Design Flowsheet Reactor Design Fuel Processing Heat Exchange and Steam Systems Capital Cost Estimates Reactor Power Plant Fuel Plant Recycle Nuclear Performance and Fuel Cycle Analyses Analysis Procedures Basic Assumptions Nuclear Design Analysis Power Cost and Fuel Utilization Characteristics

172 172 172 174 177 181 182 182 182 186 186 186 189 191

7. MOLTEN-SALT REACTOR PROCESSING STUDIES Semi-continuous Distillation Fuel Reconstitution Continuous Fluorination of a Molten Salt Chromium Fluoride Trapping Design and Evaluation Study Description of Fuel Process Description of Fertile Process Waste Treatment Off-Gas Treatment Summary of Capital and Operating Costs Processing Cost

193 194 199 202 202 203 204 208 208 209 209 210

130 133 136 136 139 141 145 152 152 154 154 162 165 167 168

ORNL-4037 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending August 31, 1966 SUMMARY

iii

INTRODUCTION

1 Part 1. MOLTEN-SALT REACTOR EXPERIMENT

1. MSRE OPERATIONS AND ANALYSIS 1.1 Chronological Account of Operations and Maintenance 1.2 Reactivity Balance Reactivity Balances at Power Reactivity Balances at Low Power 1.3 Xenon Poisoning Predicted Steady-State 135Xe Poisoning Analysis of Transient 135Xe Poisoning 1.4 Circulating Bubbles 1.5 Salt Transport Gradual Transfer to Overflow Tank Overfill 1.6 Power Measurements Heat Balance Nuclear Instruments Radiator Air Flow 1.7 Radiation Heating Fuel-Pump Tank Reactor Vessel Thermal Shield 1.8 Reactor Dynamics 1.9 Equipment Performance Heat Transfer Main Blowers Radiator Enclosure Fuel Off-Gas System Treated Cooling-Water System Component-Cooling System Salt-Pump Oil Systems Electrical System Control Rods and Drives Samplers Containment Shielding and Radiation 1.10 Instrumentation and Controls Operating Experience --- Process and Nuclear Instruments Data System Control-System Design

7 7 10 11 12 13 14 16 22 24 24 24 25 25 26 26 27 27 28 29 29 35 35 39 41 43 47 48 50 51 53 53 54 56 57 58 59 61

2. COMPONENT DEVELOPMENT 2.1 Freeze Valves

65 65

2.2 Control Rods 2.3 Control-Rod Drive Units 2.4 Radiator Doors 2.5 Sampler-Enricher Replacement of Manipulator Boots Replacement of the Capsule Latch Repair of an Open Electrical Circuit Recovery of a Capsule Operational Valve Leakage Contamination of Removal Valve Seals Miscellaneous Problems Changes to the Control Circuit 2.6 Coolant Sampler 2.7 Fuel Processing System Sampler 2.8 Off-Gas Filter Assembly Filter Medium Heat Dissipation Particle Trap Charcoal Trap 2.9 524 Charcoal Bed 2.10 Remote Maintenance

65 66 67 70 70 71 71 72 72 72 73 73 73 74 74 74 74 75 76 77 77

3. PUMP DEVELOPMENT 3.1 MSRE Pumps Molten-Salt Pump Operation in the Prototype Pump Test Facility Pump Rotary Element Modification Lubrication System MK-2 Fuel Pump 3.2 Other Molten-Salt Pumps PK-P Fuel-Pump High-Temperature Endurance Test Pump Containing a Molten-Salt-Lubricated Journal Bearing

81 81 81 82 82 82 82 82 82

4. INSTRUMENT DEVELOPMENT 4.1 Temperature Scanner 4.2 High-Temperature, NaK-Filled, Differential-Pressure Transmitter 4.3 Molten-Salt Level Detectors 4.4 Helium Control Valve Trim Replacement

84 84 85 85 86

5. REACTOR ANALYSIS 5.1 Analysis of Rod Drop Experiments Description of .Experiments Analysis Procedures Results

88 88 88 89 91

Part 2. MATERIALS STUDIES 6. MSRP MATERIALS 6.1 MSR Materials Surveillance Testing 6.2 Evaluation of Possible MSRE Radiator Tubing Contamination with Aluminum 6.3 Evaluation of Graphite 6.4 Internal Stress Problem in Graphite Moderator Blocks 6.5 Brazing of Graphite 6.6 Corrosion of Graphite-to-Metal Brazed Joints 6.7 Welding Development of Hastelloy N Effect of Irradiation on the Mechanical Properties of Hastelloy N

97 97 103 102 110 112 115 117 117

Characterization of Hastelloy N for Service at 932째C 6.8 Thermal Convection Loops 7. CHEMISTRY 7.1 Chemistry of the MSRE Behavior of Fuel and Coolant Salt 7.2 Physical Chemistry of Fluoride Melts Viscosity and Density of Molten Beryllium Fluoride Transpiration Studies in Support of the Vacuum Distillation Process Estimated Thermophysical Properties of MSBR Coolant Salt 7.3 Separation in Molten Fluorides Extraction of Rare Earths from Molten Fluorides into Molten Metals Removal of Rare Earths from Molten Fluorides by Simultaneous Precipitation with UF3 Removal of Protactinium from Molten Fluorides by Oxide Precipitation Extraction of Protactinium from Molten Fluorides into Molten Metals Protactinium Studies in the High-Alpha Molten-Salt Laboratory 7.4 Radiation Chemistry Xenon Diffusion and Possible Formation of Cesium Carbide in an MSBR Fission Product Behavior in the MSRE 7.5 Development and Evaluation of Analytical Methods for Molten-Salt Reactors Determination of Oxide in Radioactive MSRE Samples Spectrophotometric Studies of Molten-Salt Reactor Fuels Voltammetric and Chronopotentiometric Studies of Uranium in Molten LiF-BeF2-ZrF4 In-Line Test Facility Analysis of Helium Blanker Gas 7.6 Development and Evaluation of Equipment and Procedures for Analyzing Radioactive MSEE Salt Samples Sample Analyses Quality-Control Program

125 130 134 134 134 139 139 140 141 142 142 145 147 148 156 158 158 165 191 191 193 195 196 196 199 200 200

Part 3. MOLTEN-SALT BREEDER REACTOR STUDIES 8. MOLTEN-SALT BREEDER REACTOR DESIGN STUDIES 8.1 Design Changes in MSBR Plant 8.2 Modular-Type Plant 8.3 Steam Cycle with Alternative Feedwater Temperature 8.4 Additional Design Concepts

207 207 212 217 223

9. MOLTEN-SALT REACTOR PROCESSING STUDIES 9.1 Semicontinuous Distillation 9.2 Continuous Fluorination of a Molten Salt 9.3 Alternative Chemical Processing Methods for an MSBR Reduction Precipitation Li-Bi Alloy Extraction

227 228 232 233 235 237

ORNL-4119 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending February 28, 1967 SUMMARY

1

INTRODUCTION

9 PART 1. MOLTEN-SALT REACTOR EXPERIMENT

1. MSRE OPERATIONS 1.1 Chronological Account of Operations and Maintenance 1.2 Reactivity Balance Experience Circulating Bubbles 1.3 Thermal Effects of Operation Radiation Heating Thermal Cycle History 1.4 Reactor Dynamics 1.5 Equipment Performance Heat Transfer Main Blowers Radiator Enclosure Off-Gas Systems Cooling-Water Systems Component-Cooling System Salt-Pump Oil Systems Electrical System Heaters Control Rods and Drives Samplers Containment

11 11 14 14 17 18 18 19 20 21 21 25 26 27 31 32 34 34 35 36 36 37

2. COMPONENT DEVELOPMENT 2.1 Sampler-Enricher Contamination Capsule Support Wire Seal Leakage Maintenance 2.2 Coolant Sampler 2.3 Fuel Processing Sampler 2.4 Off-Gas Sampler 2.5 Off-Gas Filter - Mk II 2.6 Feltmetal Capacity Test Assumptions 46 Experimental Procedure Results 2.7 Examination of the Mk I Off-Gas Filter Pressure Drop Tests Disassembly

39 39 39 40 40 40 41 41 41 42 45 46 47 47 48 50

Observations Analytical Results 2.8 Migration of Short-Lived Gaseous Products into the Graphite 2.9 Remote Maintenance Summary of Remote Maintenance Tasks Performed Radiation Levels Contamination Conclusion

50 55 56 59 60 61 63 63

3. PUMP DEVELOPMENT 3.1 MSRE Pumps Molten-Salt Pump Operation in the Prototype Pump Test Facility MK-2 Fuel Pump Stress Tests of Pump Tank Discharge-Nozzle Attachment Spare Rotary Elements for MSRE Fuel and Coolant Salt Pumps Lubrication System 3.2 Other Molten-Salt Pumps Fuel-Pump High-Temperature Endurance Test Facility

64 64 64 64 65 65 66 66 66

4. INSTRUMENT DESIGN AND DEVELOPMENT 4.1 Instrumentation and Controls Design Off-Gas Sampler Design Control System Design 4.2 MSRE Operating Experience Control System Relays Temperature Scanner System Valves Nuclear Instrumentation Electronic Switches Thermocouples Coolant-Pump Radiation Monitor Safety System 4.3 Data System 4.4 Instrument Development Performance – General Temperature Scanner High-Temperature NaK-Filled Differential Pressure Transmitter Ultrasonic Level Probe MSRE Fuel Distillation System Level Probe Bell-Float-Type Level Indicator for the Mark II Pump

67 67 67 68 71 71 71 71 71 72 72 72 72 73 75 75 75 76 76 76 76

5. MSRE REACTOR ANALYSIS 5.1 Neutron Reaction Rates in the MSRE Spectrum 5.2 Isotopic Changes and Associated Long-Term Reactivity Effects During Reactor Operation 5.3 Analysis of Transient 135Xe Poisoning

79 79 83 86

PART 2. MATERIALS STUDIES 6. MOLTEN-SALT REACTOR PROGRAM MATERIALS 6.1 MSRE Surveillance Program - Hastelloy N 6.2 Mechanical Properties of Hastelloy N 6.3 Precursors of MSBR Graphite 6.4 Graphite Irradiations 6.5 Brazing of Graphite Large Graphite-to-Hastelloy-N Assemblies

95 95 103 108 110 111 111

6.6 Corrosion Resistance of Graphite-to-Metal Brazed Joints 6.7 Thermal Convection Loops 6.8 Evaluation of MSRE Radiator Tubing Contaminated with Aluminum

111 115 116

7. CHEMISTRY 7.1 Chemistry of the MSRE Fuel Salt Composition and Purity MSRE Fuel Circuit Corrosion Extent of UF4 Reduction During MSRE Fuel Preparation Adjustment of the UF3 Concentration in the MSRE Fuel Salt 7.2 Fission Product Behavior in the MSRE Long-Term Surveillance Specimens Uranium Analyses of Graphite Specimens Fuel Salt Samples Effect of Operating Conditions Effect of Beryllium Additions Pump Bowl Volatilization and Plating Tests Uranium on Pump Bowl Metal Specimens Freeze Valve Capsule Experiments Special Pump Bowl Tests General Discussion of Fission Product Behavior 7.3 Physical Chemistry of Fluoride Melts The Oxide Chemistry of LiF-BeF2-ZrF4 Mixtures Solubilities of SmF3 and NdF3 in Molten LiF-BeF2 (66-34 mole %) Possible MSBR Blanket-Salt Mixtures 7.4 Separations in Molten Fluorides Removal of Rare Earths from Molten Fluorides by Precipitation on Solid UF3 Extraction of Protactinium from Molten Fluorides into Molten Metals Extraction of Rare Earths from Molten Fluorides into Molten Metals Protactinium Studies in the High-Alpha Molten-Salt Laboratory Preliminary Study of the System LiF-ThF4-PaF4 7.5 Development and Evaluation of Analytical Methods for Molten-Salt Reactors Determinations of Oxide in MSRE Salts Determination of U3/U4 Ratios in Radioactive Fuel by a Hydrogen Reduction Method EMF Measurements on the Nickel-Nickel(II) Couple in Molten Fluorides Studies of the Anodic Uranium Wave in Molten LiF-BeF-ZrF4 Spectrophotometric Studies of Molten-Salt Reactor Fuels 7.6 Analytical Chemistry Analyses of Radioactive MSRE Fuels Sample Analyses Quality Control Program

118 118 118 120 121 123 124 125 128 130 131 131 134 138 138 141 142 144 144 144 146 149 149 150 152 153 155 156 156 158 162 163 163 164 165 165

8. MOLTEN-SALT CONVECTION LOOPS IN THE ORR 8.1 Objectives and Description 8.2 First Loop Experiment In-Pile Irradiation Assembly Operations Chemical Analysis of Salt Corrosion Fission Products Nuclear Heat and Neutron Flux Hot-Cell Examination of Components 8.3 Evaluation of System Performance Heaters Coolers Temperature Control Sampling and Addition

167 167 168 168 168 168 169 169 169 169 171 171 171 171 171

Salt Circulation 8.4 Second In-Pile Irradiation Assembly Operation

172 172 173

PART 3. BREEDER REACTOR DESIGN STUDIES 9. MOLTEN-SALT BREEDER REACTOR DESIGN STUDIES 9.1 General 9.2 Flowsheet 9.3 Reactor Cell Component Arrangement 9.4 Component Design Reactor Vessel Fuel Heat Exchanger Blanket Heat Exchanger 9.5 Reactor Physics 9.6 MSBR Gas Handling System Xenon Removal Mechanical Design Gas Injector System Bubble Separator System Volume Holdup System Noncritical Components

174 174 177 179 182 182 186 190 193 199 199 200 200 202 202 203

10. MOLTEN-SALT REACTOR PROCESSING STUDIES 10.1 Continuous Fluorination of a Molten Salt Nonprotected System Protected System 10.2 Molten-Salt Distillation Studies Relative Volatility Measurement Vaporization Rate Studies Buildup of Nonvolatiles at a Vaporizing Surface 10.3 Vacuum Distillation Experiment with MSRE Fuel Salt

204 204 204 205 206 206 206 208 211

ORNL-4191 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending August 31, 1967 INTRODUCTION

1

SUMMARY

3 PART I. MOLTEN-SALT REACTOR EXPERIMENT

1. MSRE OPERATIONS 1.1 Chronological Account of Operations and Maintenance 1.2 Reactivity Balance Balances at Power Balances at Zero Power 1.3 Thermal Effects of Operation Radiation Heating Thermal Cycle History Temperature Measurement Fuel Salt Afterheat 1.4 Equipment Performance Heat Transfer Main Blowers Radiator Enclosure Off-Gas Systems Cooling Water Systems Component Cooling System Salt Pump Oil Systems Electrical System Heaters Control Rods and Drives Salt Samplers Containment

13 13 19 19 21 22 22 22 22 24 25 25 26 26 27 29 29 30 31 31 31 31 33

2. COMPONENT DEVELOPMENT 2.1 Off-Gas Sampler 2.2 Remote Maintenance Preparations for Shutdown After Run 11 Evaluation of Remote Maintenance After Run 11 Repair of Sampler-Enricher and Recovery of Latch 2.3 Decontamination Studies 2.4 Development of a Scanning Device for Measuring the Radiation Level of Remote Sources Experiment with a 5-curie 137Cs Gamma Source Gamma Scan of the MSRE Heat Exchanger Gamma Energy Spectrum Scan of the MSRE Heat Exchanger 2.5 Pumps Mark-2 Fuel Pump Spare Rotary Elements for MSRE Fuel and Coolant Salt Pumps Stress Tests of Pump Tank Discharge Nozzle Attachment MSRE Oil Pumps Oil Pump Endurance Test

36 36 36 36 37 37 40 40 41 43 43 45 45 45 46 46 46

3. INSTRUMENTS AND CONTROLS 3.1 MSRE Operating Experience Control System Components Nuclear Instruments Safety System 3.2 Control System Design

47 47 47 47 48 48

4. MSRE REACTOR ANALYSIS 4.1 Introduction 4.2 Neutron Energy Spectra in MSRE and MSBR 4.3 Other Neutronic Characteristics of MSRE with 233U Fuel Critical Loading, Rod Worth, and Reactivity Coefficients Fission Rate and Thermal Flux Spatial Distributions Reactor-Average Fluxes and Reaction Cross Sections Effect of Circulation on Delayed-Neutron Precursors Samarium Poisoning Effects 4.4 MSRE Dynamics with 233U Fuel

50 50 50 54 54 55 55 58 60 61

PART 2. MSBR DESIGN AND DEVELOPMENT 5. DESIGN 5.1 General 5.2 Cell Arrangement 5.3 Reactor 5.4 Fuel Heat Exchanger 5.5 Blanket Heat Exchanger 5.6 Fuel Drain Tanks 5.7 Blanket and Coolant Salt Drain Tanks 5.8 Steam Generator-Superheater and Reheater

63 63 65 71 76 76 79 79 81

6. REACTOR PHYSICS 6.1 MSBR Physics Analysis Optimization of Reactor Parameters Useful Life of Moderator Graphite Flux Flattening Temperature Coefficients of Reactivity

82 82 82 84 87 88

7. SYSTEMS AND COMPONENTS DEVELOPMENT 7.1 Noble-Gas Behavior in the MSBR 7.2 MSBR Fuel Cell Operation with Molten Salt 7.3 Sodium Fluoroborate Circulating Loop Test 7.4 MSBR Pumps Survey of Pump Experience Circulating Liquid Metals and Molten Salts Introduction of MSBR Pump Program Fuel and Blanket Salt Pumps Coolant Salt Pumps Water Pump Test Facility Molten-Salt Bearing Tests Rotor-Dynamics Feasibility Investigation Other Molten-Salt Pumps

90 90 95 95 96 96 96 97 99 99 100 100 101

PART 3. CHEMISTRY 8. CHEMISTRY OF THE MSRE 8.1 MSRE Salt Composition and Purity Fuel Salt Coolant Salt Flush Salt Implications of Current Experience in Future Operations 8.2 MSRE Fuel Circuit Corrosion Chemistry 8.3 Adjustment of the UF3 Concentration of the Fuel Salt

102 102 103 103 103 108 110 110

9. FISSION PRODUCT BEHAVIOR IN THE MSRE 9.1 Fission Products in MSRE Cover Gas 9.2 Fission Products in MSRE Fuel 9.3 Examination of MSRE Surveillance Specimens After 24,000 MW*hr Examination of Graphite Examination of Hastelloy N Fission Product Distribution in MSRE 9.4 Deposition of Fission Products from MSRE Gas Stream on Metal Specimens 9.5 Deposition of Fission Products on Graphites in MSRE Pump Bowl

116 116 119 121 121 124 125 128 131

10. STUDIES WITH LiF-BeF2 MELTS 10.1 Oxide Chemistry of ThF4-UF4 Melts 10.2 Containment of Molten Fluorides in Silica Chemistry Spectrophotometric Measurements with Silica Cells 10.3 Electrical Conductivity of Molten Fluorides and Fluoroborates

136 136 137 137 139 140

11. BEHAVIOR OF MOLYBDENUM FLUORIDES 11.1 Synthesis of Molybdenum Fluorides 11.2 Reaction of Molybdenum Fluorides with Molten LiF-BeF2 Mixtures 11.3 Mass Spectrometry of Molybdenum Fluorides

142 142 143 144

12. SEPARATION OF FISSION PRODUCTS AND OF PROTACTINIUM FROM MOLTEN FLUORIDES 12.1 Extraction of Protactinium from Molten Fluorides into Molten Metals 12.2 Stability of Protactinium-Bismuth Solutions Contained in Graphite 12.3 Attempted Electrolytic Deposition of Protactinium 12.4 Protactinium Studies in the High-Alpha Molten-Salt Laboratory Reduction of Iron Dissolved in Molten LiF-ThF4 Thorium Reduction in the Presence of an Iron Surface (Brillo Process) Thorium Reduction Followed by Filtration Conclusion 12.5 MSBR Fuel Reprocessing by Reductive Extraction into Molten Bismuth 12.6 Reductive Extraction of Cerium from LiF-BeF2 (66-34 Mole %) into Pb-Bi Eutectic Mixture

148 148 149 151 153 153 153 154 154 154 156

13. BEHAVIOR OF BF3 AND FLUOROBORATE MIXTURES 13.1 Phase Relations in Fluoroborate Systems 13.2 Dissociation Vapor Pressures in the NaBF4-NaF System 13.3 Reactions of Fluoroborates with Chromium and Other Hastelloy N Constituents Apparent Mass Transfer of Nickel 13.4 Reaction of BF3 with Chromium Metal at 650째C 13.5 Compatibility of BF3 with Gulfspin-35 Pump Oil at 150째F

158 158 159 161 163 163 164

14. DEVELOPMENT AND EVALUATION OF ANALYTICAL METHODS FOR MOLTEN-SALT REACTORS

166

14.1 Determination of Oxide in MSRE Salts 14.2 Determination of U3+ in Radioactive Fuel by a Hydrogen Reduction Method 14.3 In-Line Test Facility 14.4 Electroreduction of Uranium(IV) in Molten LiF-BeF2-ZrF4 at Fast Scan Rates and Short Transition Times 14.5 Spectrophotometric Studies of Molten Fluoride Salts 14.6 Analysis of Off-Gas from Compatibility Tests of MSRE Pump Oil with BF3 14.7 Development of a Gas Chromatograph for the MSRE Blanket Gas

167 167 169 169 171 172 172

PART 4. MOLTEN-SALT IRRADIATION EXPERIMENTS 15. MOLTEN-SALT CONVECTION LOOP IN THE ORR 15.1 Loop Description 15.2 Operation 15.3 Operating Temperatures 15.4 Salt Circulation by Convection 15.5 Nuclear Heat, Neutron Flux, and Salt Power Density 15.6 Corrosion 15.7 Oxygen Analysis 15.8 Crack in the Core Outlet Pipe 15.9 Cutup of Loop and Preparation of Samples 15.10 Metallographic Examination 15.11 Isotope Activity Calculation from Flux and Inventory History 15.12 Isotope Activity Balance 15.13 Uranium-235 Observed in Graphite Samples 15.14 Penetration of Fission Products into Graphite and Deposition onto Surfaces 15.15 Gamma Irradiation of Fuel Salt in the Solid Phase

176 176 177 179 180 180 181 182 182 184 185 187 190 190 192 193

PART 5. MATERIALS DEVELOPMENT 16. MSRE SURVEILLANCE PROGRAM 16.1 General Description of the Surveillance Facility and Observations on Samples Removed 16.2 Mechanical Properties of the MSRE Hastelloy N Surveillance Specimens

196 196 200

17. GRAPHITE STUDIES 17.1 Materials Procurement and Property Evaluation 17.2 Graphite Surface Sealing with Metals 17.3 Gas Impregnation of MSBR Graphites 17.4 Irradiation of Graphite

208 208 211 212 215

18. HASTELLOY N STUDIES 18.1 Improving the Resistance of Hastelloy N to Radiation Damage

by Composition Modifications 18.2 Aging Studies on Titanium-Modified Hastelloy N 18.3 Phase Identification Studies in Hastelloy N 18.4 Hot-Ductility Studies of Zirconium-Bearing Modified Hastelloy N 18.5 Residual Stress Measurements in Hastelloy N Welds 18.6 Corrosion Studies Fuel Salts Coolant Salts Equipment Modifications 18.7 Titanium Diffusion in Hastelloy N 18.8 Hastelloy N-Tellurium Compatibility

217 217 217 219 221 223 226 226 227 230 230 233

19. GRAPHITE-TO-METAL JOINING 19.1 Brazing of Graphite to Hastelloy N Joint Design Brazing Development 19.2 Compatibility of Graphite-Molybdenum Brazed joints with Molten Fluoride Salts

236 236 236 237 237

PART 6. MOLTEN-SALT PROCESSING AND PREPARATION 20. VAPOR-LIQUID EQUILIBRIUM DATA IN MOLTEN-SALT MIXTURES

239

21. RELATIVE VOLATILITY MEASUREMENT BY THE TRANSPIRATION METHOD

242

22. DISTILLATION OF MSRE FUEL CARRIER SALT

243

23. STEADY-STATE FISSION PRODUCT CONCENTRATIONS AND HEAT GENERATION IN AN MSBR AND PROCESSING PLANT Heat Generation in a Molten-Salt Still

245 247

24. REDUCTIVE EXTRACTION OF RARE EARTHS FROM FUEL. SALT

248

25. MODIFICATIONS TO MSRE FUEL PROCESSING FACILITY FOR SHORT DECAY CYCLE

251

26. PREPARATION OF 233UF4-7LiF FUEL CONCENTRATE FOR THE MSRE Process Equipment and Operations Status

252 252 252 253

ORNL-4254 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending February 29, 1968 INTRODUCTION

ix

SUMMARY

xi PART 1. MOLTEN-SALT REACTOR EXPERIMENT

1. MSRE OPERATIONS 1.1 Chronological Account of Operations and Maintenance 1.2 Operations Analysis 1.2.1 Reactivity Balance 1.2.2 Variations in Reactor Access Nozzle Temperatures 1.2.3 Radiation Heating 1.2.4 Thermal Cycle History 1.2.5 236U Indication of Integrated Power 1.3 Equipment Performance 1.3.1 Salt Pumps 1.3.2 Heat Transfer 1.3.3 Salt Samplers 1.3.4 Control Rods and Drives 1.3.5 Radiator Enclosure 1.3.6 Off-Gas Systems 1.3.7 Main Blowers 1.3.8 Heaters 1.3.9 Electrical System 1.3.10 Salt Pump Oil Systems 1.3.11 Cooling Water System 1.3.12 Component Cooling Systems 1.3.13 Containment and Ventilation

1 1 3 3 7 9 9 10 11 11 11 12 13 13 13 14 15 15 16 16 17 17

2. COMPONENT DEVELOPMENT 2.1 Off-Gas Sampler 2.2 Fuel Sampler-Enricher 2.3 Decontamination Studies 2.4 Study of Pin-Hole Camera for Gamma Source Mapping 2.5 Freeze-Flange Thermal Cycle Tests 2.6 Pumps 2.6.1 Mark 2 Fuel Pump 2.6.2 MSRE Oil Pumps 2.6.3 Oil Pump Endurance Test

19 19 20 20 22 23 29 29 29 29

3. INSTRUMENTS AND CONTROLS 3.1 MSRE Operating Experience 3.1.1 Safety System Components 3.1.2 Thermocouples 3.1.3 Other Instruments and Controls 3.2 Control System Design 3.3 MSRE Neutron Noise Analysis

30 30 30 30 31 31 32

3.4 Test of MSRE Rod Control System Under Simulated 233U Loading Conditions 3.5 Analog Computer Studies of the MSRE System with 233U Fuel Loading 4. MSRE REACTOR ANALYSIS 4.1 Introduction 4.2 Simulation of Nuclear Excursion Incidents 4.2.1 Uncontrolled Rod Withdrawal 4.2.2 Return of Separated Uranium to the Core 4.3 Detection of Anomalous Reactivity Effects

32 35 36 36 37 37 40 47

PART 2. MSBR DESIGN AND DEVELOPMENT 5. DESIGN 5.1 General 5.2 Flow Diagram 5.3 Plant Layout 5.4 Reactor Vessel and Core 5.5 Primary Heat Exchanger 5.6 Fuel Drain Tank

51 51 51 53 55 61 61

6. REACTOR PHYSICS 6.1 MSBR Physics Analysis 6.1.1 Reference Reactor 6.1.2 Fuel-Cycle Costs 6.1.3 Cell Calculations 6.1.4 Reactivity Coefficients 6.1.5 Measurements of Eta for 233U and 235U in the MSRE

66 66 66 70 70 71 72

7. SYSTEMS AND COMPONENTS DEVELOPMENT 7.1 Noble Gas Behavior in an MSBR 7.2 Sodium Fluoroborate Circulating Loop Test 7.3 MSBR Pumps 7.3.1 Pump Program 7.3.2 Fuel Salt Pump 7.3.3 Coolant Salt Pump 7.3.4 Molten-Salt Pump Test Facility 7.3.5 Molten-Salt Bearing Program 7.3.6 Rotor-Dynamics Feasibility Investigation 7.4 Remote Maintenance

74 74 75 75 75 76 78 78 79 82 82

8. MSBR INSTRUMENTATION AND CONTROLS 8.1 Analog Computer Studies

85 85

PART 3. CHEMISTRY 9. CHEMISTRY OF THE MSRE 9.1 Fuel Salt Composition and Purity 9.2 MSRE Fuel Circuit Corrosion Chemistry 9.3 Isotopic Composition of Uranium in MSRE Fuel Salt

88 89 90 93

10. FISSION PRODUCT BEHAVIOR 10.1 Fission Product Behavior in the MSRE 10.1.1 Fission Products in the MSRE Fuel 10.1.2 Fission Products in the MSRE Cover Gas

94 94 94 96

10.1.3 Deposition of Fission Products from MSRE Cover Gas on Metal Specimens 10.1.4 Examination of MSRE Surveillance Specimens After 24,000 MW*hr 10.1.5 Hot-Cell Tests on Fission Product Volatilization from Molten MSRE Fuel 10.1.6 Miscellaneous Tests 10.2 Fission Product Distribution in an MSRE Graphite Surveillance Specimen 10.3 Proton Reaction Analysis for Lithium and Fluorine in MSR Graphite 10.4 Surface Phenomena in Molten Salts

96 99 100 108 115 119 125

11. CHEMISTRY OF FISSION PRODUCT FLUORIDES 11.1 Properties of Molybdenum Fluorides 11.1.1 Synthesis of MoF3 and MoF5 11.1.2 Lithium Fluoromolybdates(III) 11.1.3 Kinetics of MoF3 Behavior in 2LiF-BeF2 11.2 Mass Spectrometry of the Molybdenum Fluorides 11.3 Spectroscopic Studies of Fission Product Fluorides 11.4 Preparation of Niobium Pentafluoride

129 129 129 130 131 134 136 137

12. PHYSICAL CHEMISTRY OF MOLTEN SALTS 12.1 Thermodynamics of LiF-BeF2 Melts by EMF Measurements 12.2 Electrolysis of LiF-BeF2 Mixtures with a Bismuth Cathode 12.3 A Review of Electrical Conductivities in Molten Fluoride Systems 12.4 Measurement of Specific Conductance in LiF-BeF2 (66-34 mole %) 12.5 A Stirred Reaction Vessel for Molten Fluorides 12.6 The Chemistry of Silica in Molten LiF-BeF2 12.7 A Silica Cell and Furnace for Electrochemical Measurements with Fused Fluorides 12.8 Status of the Molten-Salt Chemistry Information Center

138 138 140 141 144 146 146 149 149

13. CHEMISTRY OF MOLTEN-SALT REACTOR FUEL REPROCESSING TECHNOLOGY 13.1 MSBR Fuel Reprocessing by Reductive Extraction into Molten Bismuth 13.2 Removal of Structural Metal Fluorides from a Simulated MSRE Fuel Solvent 13.2.1 Reduction of Structural Metal Fluorides 13.2.2 Salt Filtration Studies 13.3 Protactinium Studies in the High-Alpha Molten-Salt Laboratory 13.3.1 Protactinium Reduction by Solid Thorium in the Near Absence of Iron 13.3.2 Reduction of Protactinium by Bismuth-Uranium Alloy 13.3.3 Reduction of Protactinium by Bismuth-Thorium Alloys 13.3.4 Two-Region Breeder Blanket Composition 13.3.5 Single-Region Fuel Composition

152 152 155 155 157 159 159 159 160 160 161

14. BEHAVIOR OF BF3 AND FLUOROBORATE MIXTURES 14.1 Phase Relations in Fluoroborate Systems 14.1.1 The System NaF-NaBF4-KBF4-KF 14.2 Nonideality of Mixing in Potassium Fluoroborate-Sodium (or Potassium) Fluoride Systems 14.3 Heat Content of NaBF4-NaF (92.5-7.5 mole %) 14.4 The Solubility of Thorium Metal in Lithium Fluoride-Thorium Tetrafluoride Mixtures 14.5 Dissociation Pressure of BF3 for the MSRE Substitute Coolant 14.6 Chemical Thermodynamics of the System NaBF4NaF 14.7 Corrosion of Hastelloy N and Its Constituents in Fluoroborate Melts 14.8 Compatibility and Immiscibility of Molten Fluorides

166 166 166 167 168 168 169 170 171 171

PART 4. MOLTEN-SALT IRRADIATION EXPERIMENTS 15. MOLTEN-SALT CONVECTION LOOP IN THE ORR 15.1 Isotope Activity Balance (Loop 2) 15.2 Penetration of Fission Products into Graphite and Deposition onto Surfaces

174 175 175

15.3 Studies of Surface Wetting of Graphite by Molten Salt 15.4 Design of a Third In-Pile Molten-Salt Loop 16. GAMMA IRRADIATION OF FLUOROBORATE

178 178 180

PART 5. MATERIALS DEVELOPMENT 17. MSRE SURVEILLANCE PROGRAM 17.1 General Comments 17.2 Examination of Hastelloy N Specimens from MSRE Surveillance Facility

183 183 184

18. GRAPHITE STUDIES 18.1 Procurement of Special Grades of Graphite 18.2 Porosity Created in Grade AXF Graphite by Oxidation Pretreatment 18.3 X-Ray Studies on Graphite 18.4 Gas Impregnation of Graphite with Carbon 18.5 Graphite Surface Sealing with Metals 18.6 Graphite Irradiation Program 18.7 Nondestructive Testing Studies 18.7.1 Graphite Ultrasonic Velocity Measurements 18.7.2 Low-Voltage Radiography

188 188 189 190 191 192 195 196 196 197

19. HASTELLOY N 19.1 Influence of Strain Rate on the Fracture Strain of Hastelloy N 19.2 Status of Development of the Modified Alloy 19.3 Effect of Carbon and Titanium on the Unirradiated Creep-Rupture Properties of Ni-Mo-Cr Alloys 19.4 Electrical Resistivity of Titanium-Modified Hastelloy N 19.5 Electron Microscope Studies of Hastelloy N 19.5.1 Phase Identification Studies in Hastelloy N 19.5.2 Effect of Silicon on Precipitation in Hastelloy N 19.5.3 Titanium-Modified Hastelloy N 19.5.4 Summary 19.6 Diffusion of Titanium in Modified Hastelloy N 19.7 Measurement of Residual Stresses in Hastelloy N Welds 19.7.1 Experimental Results 19.8 Application of the Narrow-Gap Welding Process to the joining of Hastelloy N 19.9 Natural Circulation Loops and Test Capsules 19.9.1 Fuel Salts 19.9.2 Blanket Salts 19.9.3 Coolant Salts 19.10 Forced Circulation Loop 19.11 Oxidation of Hastelloy N

198 198 201

20. GRAPHITE-TO-METAL JOINING 20.1 Graphite Brazing Development 20.2 Radiation Stability of Brazing Alloys of Interest for Brazing Graphite 20.3 Graphite-to Hastelloy N Transition joint 20.3.1 Conceptual Design 20.3.2 Heavy-Metal Alloy Development 20.4 Nondestructive Testing Evaluation of Graphite-to-Metal joints

231 231 234 235 235 236 238

21. SUPPORT FOR COMPONENTS DEVELOPMENT PROGRAM 21.1 Remote Welding

240 240

204 205 206 206 209 212 213 213 215 216 217 218 218 221 221 226 228

PART 6. MOLTEN-SALT PROCESSING AND PREPARATION 22. MEASUREMENT OF DISTRIBUTION COEFFICIENTS IN MOLTEN-SALT-METAL SYSTEMS 22.1 Extraction of Uranium and Rare Earths from Fuel Salt of Two-Fluid MSBR's 22.2 Extraction of Uranium from Single-Fluid MSBR Fuel 22.3 Experimental Procedure and Lithium "Loss"

241 242 243 247

23. PROTACTINIUM REMOVAL FROM A SINGLE-FLUID MSBR

248

24. CONTINUOUS FLUORINATION OF MOLTEN SALT

252

25. RELATIVE VOLATILITY MEASUREMENTS BY THE TRANSPIRATION METHOD

255

26. DISTILLATION OF MSRE FUEL CARRIER SALT

258

27. PROTACTINIUM REMOVAL FROM A TWO-FLUID MSBR

260

28. RECOVERY OF URANIUM FROM MSRE FUEL SALT BY FLUORINATION 28.1 Fluorination-Corrosion Study 28.2 Fission Product Behavior - Analytical Assistance Program

264 264 266

29. MSRE FUEL SALT PROCESSING

269

30. PREPARATION OF 7LiF-233UF4 FUEL CONCENTRATE FOR THE MSRE 30.1 Equipment Changes 30.2 Equipment and Process Status

270 270 271

31. DECAY HEAT GENERATION RATE IN A SINGLE-REGION MOLTEN-SALT REACTOR

275

ORNL-4344 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending August 31, 1968 INTRODUCTION

xi

SUMMARY

xiii PART 1. MOLTEN-SALT REACTOR EXPERIMENT

1. MSRE OPERATIONS 1.1 Chronological Account of Operations and Maintenance 1.2 Chemical Processing 1.2.1 Operating Summary 1.2.2 Data Analysis 1.2.3 Equipment Performance 1.3 Reactor Operations Analysis 1.3.1 Long-Term Variations in Reactivity 1.3.2 Reactivity Effects of Radiation Damage to Graphite 1.3.3 Dynamics Tests at the End of 235U Operation 1.3.4 Correlation of Circulating Void Fraction and Neutron Noise 1.3.5 Determination of Circulating Void Fraction 1.3.6 Neutron Flux near Reactor Vessel 1.3.7 Observation of Fission Products After Shutdown 1.3.8 Unscheduled Scrams During 235U Operation 1.3.9 Thermal Cycle History 1.4 Equipment 1.4.1 Heat Transfer 1.4.2 Salt Samplers 1.4.3 Control Rods and Drives 1.4.4 Radiator Enclosure 1.4.5 Off-Gas System 1.4.6 Main Blowers 1.4.7 Heaters 1.4.8 Oil Systems for Salt Pumps 1.4.9 Component Cooling System 1.4.10 Containment and Ventilation

1 1 4 4 6 10 12 12 14 14 18 19 19 22 24 24 24 24 26 29 29 30 30 31 31 31 32

2. COMPONENT DEVELOPMENT 2.1 Freeze-Flange Thermal-Cycle Tests 2.1.1 Facility Operation Problems 2.1.2 Inspection of the Flanges 2.2 Gamma Spectrometric Measurements of Fission Product Deposition 2.3 Gamma Source Mapping with Pinhole Camera Photography 2.4 Pumps 2.4.1 Mark 2 Fuel Pump 2.4.2 Oil Pump Endurance

33 33 33 33 36 40 40 40 40

3. INSTRUMENTS AND CONTROLS 3.1 MSRE Operating Experience 3.2 Control System Design

43 43 43

3.3 Analog Investigation of Control with 233U Fuel 4. MSRE REACTOR ANALYSIS 4.1 Delayed Neutron Effectiveness 4.2 Theoretical Dynamic Analysis for 233U Fuel 4.2.1 Time Response 4.2.2 Frequency-Response Calculations 4.2.3 Stability Analysis

44 45 45 46 46 48 48

PART 2. MSBR DESIGN AND DEVELOPMENT 5. DESIGN 5.1 General 5.2 Plant Layout 5.3 Flowsheet 5.4 Reactor Vessel and Core 5.6 Primary Heat Exchangers 5.6 Primary Drain System 6.7 Maintenance Procedures and Equipment

53 53 53 56 58 64 66 66

6. REACTOR PHYSICS 6.1 Physics Analysis of MSBR 6.2 Physics Analysis of MSBE

68 68 70

7. SYSTEMS AND COMPONENTS DEVELOPMENT 7.1 Noble-Gas Migration in the MSBR Reference Design 7.2 Bubble Generator 7.3 Bubble Separator 7.4 Sodium Fluoroborate Circulating Test Loop 7.4.1 Pumping Characteristics of Sodium Fluoroborate Salt 7.4.2 Restrictions in the Gas System 7.4.3 Salt Compatibility 7.4.4 NaBF4 Freeze Valve 7.5 MSBR Pumps 7.5.1 Pump Program 7.5.2 Fuel-Salt Pump 7.5.3 Coolant-Salt Pump 7.5.4 Molten-Salt Pump Test Facility 7.5.5 Rotor-Dynamics Feasibility Study 7.5.6 Molten-Salt Bearing Program 7.6 Molten-Salt Steam Generator 7.7 Remote Welding

72 72 74 74 75 76 77 78 78 78 78 80 81 81 83 84 84 85

8. MSBR INSTRUMENTATION AND CONTROLS 8.1 Control System Analyses 8.1.1 System Control Analysis 8.1.2 Dynamic Analysis of MSBR Steam Generator 8.2 Calculations of Neutron Decay After Shutdown 8.3 High-Temperature Resistance Thermometer Evaluation

88 88 88 91 93 94

9. HEAT TRANSFER AND THERMOPHYSICAL PROPERTIES 9.1 Introduction 9.2 Heat Transfer 9.3 Thermophysical Properties 9.3.1 Thermal Conductivity

96 96 96 100 100

9.3.2 Heat Capacity 9.3.3 Property Prediction 9.4 Mass Transfer to Circulating Bubbles

103 104 106

PART 3. CHEMISTRY 10. CHEMISTRY OF THE MSRE 10.1 Chemical Feasibility of Fueling Molten-Salt Reactors with Plutonium Trifluoride 10.2 Chemical Determination of Burnup in 235U Operations 10.3 High-Temperature Fuel Salt-Graphite Compatibility Experiment 10.4 Examination of a Corroded Cap from a Sample Capsule

109 110 110 112 113

11. FISSION PRODUCT BEHAVIOR 11.1 Fission Product Behavior in the MSRE 11.1.1 Examination of MSRE Surveillance Specimens After 64,000 MW*hr 11.2 Fission Product Profiles in Three MSRE Graphite Surveillance Specimens 11.2.1 Pyrolytic Graphite 11.2.2 Unimpregnated CGB (Specimen P-55) 11.2.3 Impregnated CGB (Specimen V-28) 11.2.4 Overall Results 11.3 Analysis of MSRE Graphite Sample X-13 for Fluorine and Lithium 11.4 Surface Phenomena in Molten Salts

115 115 115 141 141 142 142 146 146 150

12. PHYSICAL CHEMISTRY OF MOLTEN SALTS 12.1 Molybdenum Fluoride Chemistry 12.1.1 Synthesis of MoF3, MoF4, MoF5, and RuF3 12.1.2 Kinetic Behavior of MoF3 in Molten 2LiF-BeF2 12.2 Properties of the Alkali Fluoroborates 12.2.1 Phase Relations in Fluoroborate Systems 12.2.2 Crystal Structure of Sodium Tetrafluoroborate 12.2.3 Heat Content of NaBF4 and KBF4 12.2.4 Dissociation Pressure and Chemical Thermodynamics of the System KBF4-KF 12.2.5 Density and Viscosity of Sodium Fluoroborate Melts 12.2.6 Corrosion of Chromium by Molten Fluoroborates 12.3 Physical Properties of LiF-ThF4 and LiF-BeF2-ThF4 Mixtures 12.3.1 CeF3 Solubility in Molten Mixtures of LiF, BeF2, and ThF4 12.3.2 Solubility of Thorium Metal in Molten Lithium Fluoride-Thorium Fluoride Mixtures 12.3.3 Heat Content of LiF-BeF2-ThF4 (72-16-12 mole %) 12.3.4 Technical Memorandum on Physical Properties of Molten Salts 12.4 Electrochemical Studies 12.4.1 Electrical Conductivity of Molten LiF-BeF2 Mixtures 12.4.2 Estimated Electrical Conductivities of MSBR-Related Salts 12.4.3 Reference Electrodes for Molten Fluorides 12.5 Spectroscopy of Fluoride Media 12.5.1 The Diamond-Windowed Cell 12.5.2 Molybdenum(III) Fluoride Solution Spectra 12.5.3 K3MoF6 Synthesis and Spectrum 12.5.4 Studies of the Vapor Phase over MoF3 Solutions 12.6 Oxide Chemistry of Fluoride Melts Containing ThF4 and UF4 12.7 Chemistry of Silica in Molten LiF-BeF2

153 153 153 154 155 155 156 157 158 159 160 161 161

13. CHEMISTRY OF MOLTEN-SALT REACTOR FUEL REPROCESSING TECHNOLOGY 13.1 Reductive Extraction of 233Pa and Uranium from Molten LiF-BeF2-ThF4 Mixtures into Bismuth

174

162 163 163 163 163 166 167 168 168 170 170 170 171 172

174

13.2 Reductive Extraction of Rare Earths from Molten Mixtures of LiF, BeF2, and ThF4 into Bismuth and Bismuth Alloy Mixtures 13.2.1 Effect of Salt Composition 13.2.2 Effect of Metal-Phase Composition 13.3 Protactinium Studies in the High-Alpha Molten-Salt Laboratory 13.3.1 Tests Dealing with the Possibility of Thorium Carbide Formation 13.3.2 Tests Dealing with the Possibility of Oxide Contamination 13.3.3 Experiment with Molybdenum Container 13.3.4 Conclusions 14. DEVELOPMENT AND EVALUATION OF ANALYTICAL METHODS FOR MOLTEN-SALT REACTORS 14.1 Determination of Oxide in MSRE Salts 14.2 Determination of Uranium (III) in Radioactive MSRE Fuel by a Hydrogen-Reduction Method 14.3 Determination of Total Reducing Power of Radioactive MSRE Salts 14.4 Disproportionation of Electrochemically Generated U(V) in LiF-BeF2 ZrF4 at 500째C 14.5 Exchange Current Measurements on the Nickel-Nickel(II) Couple in Molten Fluorides 14.6 Voltammetric Studies of Chromium(II) in Molten LiF-BeF2-ZrF4 at 500째C 14.7 Development of a Molten-Salt Spectrophotometric Facility for Hot-Cell Use 14.8 Spectra of U(V) and U(VI) Species in Molten Fluoride Salts 14.9 Absorption Spectra of Several 3d Transition Metal Ions in Molten Fluoride Solution 14.10 Simultaneous Electrochemical and Spectrophotometric Study of Solutes in Molten Fluoride Salts 14.11 Development of a Gas Chromatograph for Analysis of the MSRE Blanket Gas 14.12 Analysis of MSRE Helium for Hydrocarbons 14.13 Measurement by Ge(Li) Gamma Spectroscopy of Fission Products Deposited in Components of the MSRE 14.14 In-Pile Fission-Product Penetration in MSRE and Pyrolytic Graphite 14.15 Precision Analysis of 235U by Delayed-Neutron Counting 14.16 High-Precision Polarographic Determination of Uranium 14.17 A Precise Determination of Uranium in MSRE Fuel

176 176 178 180 181 181 184 185 186 186 188 189 190 191 192 192 193 194 195 195 196 196 197 198 198 198

PART 4. MOLTEN-SALT IRRADIATION EXPERIMENTS 15. MOLTEN-SALT CONVECTION LOOP IN THE ORR 15.1 Studies of Surface Wetting of Graphite by Molten Salt

200 200

16. GAMMA IRRADIATION OF FLUOROBORATE 16.1 Gamma Dose Rates and Decay of Spent Fuel Elements 16.2 Second Fluoroborate Irradiation Experiment 16.3 Estimated Neutron Effects

203 203 203 205

17. EXAMINATION OF MSRE OFF-GAS JUMPER LINE 17.1 Chemical Analysis 17.2 Radiochemical Analysis 17.3 Discussion

206 207 207 208

PART 5. MATERIALS DEVELOPMENT 18. MSRE SURVEILLANCE PROGRAM 18.1 MSRE Surveillance Specimens 18.1.1 Examinations of Specimens Removed

211 211 213

18.1.2 New Specimens in the Surveillance Assembly 18.2 Mechanical Properties of MSRE Surveillance Specimens

214 216

19. GRAPHITE STUDIES 19.1 Procurement of Graphite 19.2 Physical Property Measurements 19.3 Bend Testing of Graphite 19.4 X-Ray 8tudies 19.5 Gas Impregnation of Graphite with Carbon 19.6 Graphite Surface Sealing with Metals 19.7 Graphite Irradiation Experiments 19.8 Small-Angle X-Ray Scattering Measurements in Graphite

224 224 226 227 228 230 231 233 235

20. HASTELLOY N 20.1 Development of Titanium-Modified Hastelloy N 20.1.1 Commercial Melts 20.1.2 Laboratory Melts 20.2 Aging of Modified Hastelloy N 20.3 Influence of Irradiation Temperatures on the Post-irradiation Mechanical Properties of Titanium-Modified Hastelloy N 20.4 Electron Microscope Studies 20.4.1 Precipitation in Standard Hastelloy N 20.4.2 Titanium-Modified Hastelloy N 20.5 Weldability of Titanium-Modified Hastelloy N 20.6 Measurement of Residual Stresses in Hastelloy N Welds 20.7 Corrosion Studies 20.7.1 Fuel Salts 20.7.2 Blanket Salts 20.7.3 Coolant Salts 20.7.4 Haynes Alloy No. 25 Corrosion 20.7.5 Flow Velocity in Natural Circulation Loops 20.8 Forced Convection Loop 20.9 Oxidation of Ni-Mo-Cr-Fe Alloys

237 237 237 238 239

21. GRAPHITE-TO-METAL JOINING 21.1 Introduction 21.2 Graphite Brazing 21.3 Graphite-Hastelloy N Transition Joint Development 2l.3.1 Heavy-Metal Alloy Development 21.3.2 Fabrication and Testing of Joints 21.4 Nondestructive Testing of Graphite-to-Metal Joints

271 271 271 272 273 273 276

22. SUPPORT FOR COMPONENTS DEVELOPMENT PROGRAM 22.1 Welding Irradiated Materials 22.1.1 Development of Apparatus and Procedures for Welding Irradiated Samples 22.1.2 Mechanical Properties of Hastelloy N Welded After Irradiation 22.2 Molten-Salt Distillation Experiment 22.2.1 Examination of Specimens from the Distillation Experiment 22.2.2 Examination of Plug from Distillation Vessel 22.3 X-Ray Examination of Bearing Coatings 22.4 Liquid-Level Probe Analysis 22.5 Fabrication of Fluted Tubing for Enhanced Heat Transfer

278 278 278 278 282 282 285 285 285 289

244 247 247 247 250 256 257 257 262 264 265 266 266 269

PART 6. MOLTEN-SALT PROCESSING AND PREPARATION INTRODUCTION

291

23. MEASUREMENT OF DISTRIBUTION COEFFICIENTS IN MOLTEN-SALT-METAL SYSTEMS 23.1 Extraction of Protactinium from Single-Fluid MSBR Fuels 23.2 Extraction of Thorium and Rare Earths from Single-Fluid MSBR Fuels 23.3 Solubility of Thorium in Bismuth

292 292 295 297

24. SIMULATED MOLTEN-SALT-LIQUID-BISMUTH CONTACTOR STUDIES

298

25. REDUCTIVE EXTRACTION ENGINEERING STUDIES

301

26. CONTINUOUS FLUORINATION OF MOLTEN SALT

302

27. DISTILLATION OF MSRE FUEL CARRIER SALT

306

28. RELATIVE VOLATILITY MEASUREMENTS BY THE TRANSPIRATION METHOD

309

29. PREPARATION OF 7LiF-233UF4 CONCENTRATE FOR THE MSRE 29.1 Cold Shakedown Run 29.2 Production of the 7LiF-233UF4 Concentrate 29.3 Packaging of the Concentrate

311 311 311 313

30. DEVELOPMENT OF THE TWO-STEP PROCESS FOR PREPARATION OF 7LiF-233UF4 FUEL CONCENTRATE FOR THE MSRE 30.1 Laboratory Test of Low-Temperature Process 30.2 Physical Behavior of Powder Beds 30.3 Oxide Impurity Level in a Product 30.4 Feasibility of Use of the Two-Step Process

318 318 320 320 320

31. PROCESS DEVELOPMENT ON THE RECOVERY OF URANIUM FROM MSRE 31.1 Fluorination-Valence State Study 31.2 Equilibrium of UF6 with NaF at 400째C; Retention of Uranium 31.3 Effect of Temperature on Sorption of UF6 by NaF: Comparison of High- and Low-Surface-Area Material 31.4 Linear Velocity in Sorption Process 31.5 Disposal of Gaseous F2 in KOH-KI-K2B4O7 Solution 31.6 Corrosion 31.7 Helium Dilution of Fluorine 31.8 Formation of KIO3 Precipitate 31.9 Neutron Poisoning with K2B4O7 31.10 Handling of Mist and Smoke from Scrub Solution

321 321 323

ORGANIZATION CHART

327

324 325 325 325 326 326 326 326

ORNL-4396 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending February 28, 1969 INTRODUCTION

xi

SUMMARY

xiii PART 1. MOLTEN-SALT REACTOR EXPERIMENT

1. MSRE OPERATIONS 1.1 Chronological Account of Operations and Maintenance 1.2 233U Zero-Power Tests 1.2.1 Critical Experiment 1.2.2 Control Rod Calibration 1.2.3 Temperature Coefficient of Reactivity 1.2.4 Concentration Coefficient of Reactivity 1.3 Operations Analysis 1.3.1 System Dynamics 1.3.2 Gas in the Fuel Salt 1.3.3 Neutron and Pressure Noise Measurements 1.3.4 Perturbations in Nuclear Power 1.3.5 Salt Transfer to Overflow Tank 1.3.6 Thermal-Convection Heat-Removal Test 1.3.7 Radiation Heating 1.3.8 Thermal Cycle History 1.4 Equipment 1.4.1 233U Loading Equipment 1.4.2 Salt Samplers 1.4.3 Control Rods and Drives 1.4.4 Off-Gas System 1.4.5 Component Cooling System 1.4.6 Containment and Ventilation 1.4.7 Electrical System 1.4.8 Heaters 1.4.9 Other

1 1 5 5 7 8 9 9 9 11 16 16 21 22 23 23 24 24 25 26 27 28 28 28 29 29

2. COMPONENT DEVELOPMENT 2.1 Freeze-Flange Thermal-Cycle Test 2.2 Pumps 2.2.1 Mark 2 Fuel Pump 2.2.2 Oil Pump Endurance Test

30 30 31 31 32

3. INSTRUMENTATION AND CONTROLS 3.1 MSRE Operating Experience 3.2 Controls System Design 3.3 MSRE Computer System

33 33 33 33

4. MSRE REACTOR ANALYSIS 4.1 Long-Term Isotopic Changes and Reactivity Effects During Operation with 233U 4.2 Analysis of Zero Power Rod-Calibration Experiments

35 35 37

4.2.1 Rod-Drop Experiments 4.2.2 Reactivity Effect of Excess Uranium 4.2.3 Summary of Rod-Calibration Information 4.3 Calculations of Reactivity Variations from Power-Time Records 4.4 Theoretical Analysis of Dynamics with 233U Fuel

38 40 41 43 45

PART 2. MSBR DESIGN AND DEVELOPMENT 5. DESIGN 5.1 General 5.2 Plant Layout 5.3 Reactor 5.4 Primary Heat Exchangers 5.5 Steam Generator and Superheater 5.6 Steam Reheater 5.7 Removal of Reactor Afterheat 5.7.1 Introduction 5.7.2 Sources of Afterheat 5.7.3 Heat-Removal Systems 5.8 Distribution of Noble-Metal Fission Products and Their Decay Heat 5.9 Reactor Temperatures, Flows, and Heat Transfer 5.9.1 Reactor Core 5.9.2 Flow and Temperature in Radial Reflector 5.9.3 Flow and Temperature in Axial Reflectors 5.9.4 Vessel Temperatures 5.10 Estimated Costs of 1000 MWe MSBR Power Station 5.11 MSBE Design 5.11.1 Introduction 5.11.2 Description of Reactor Plant

49 49 49 52 57 57 59 59 59 59 60 62 64 64 67 69 70 70 71 71 74

6. REACTOR PHYSICS 6.1 Physics Analysis of MSBR 6.1.1 Optimization of the MSBR 6.1.2 The One-Fluid MSBR Reference Design 6.1.3 Nuclear Design Studies 6.1.4 Optimum Thorium Concentration in MSBR 6.1.5 Improvements in Computational Tools 6.1.6 Gamma and Neutron Heating in MSBR 6.2 Physics Analysis of MSBE 6.2.1 MSBE Design Studies 6.3 MSBR Experimental Physics 6.3.1 Initial Results of the Experiment to Measure alpha(235U) in the MSRE

76 76 76 77 77 80 82 83 84 84 87 87

7. SYSTEMS AND COMPONENTS DEVELOPMENT 7.1 Off-Gas System 7.1.1 Volume Holdup Tank 7.2 Noble-Gas Migration in the MSBR 7.2.1 Contribution of the Noble Gases to Afterheat in the Graphite 7.2.2 Distribution of Decay Heat in the MSBR Off-Gas System 7.3 Bubble Generator 7.4 Bubble Separator 7.5 Molten-Salt Steam Generator Test Stand 7.6 Sodium Fluoroborate Circulating Test Loop 7.6.1 Pumping Characteristics of Sodium Fluoroborate Salt 7.6.2 Control of Salt Composition

90 90 90 92 92 94 95 96 98 98 100 100

7.6.3 Corrosion Product Deposition 7.6.4 Gas System Studies 7.7 MSBR Pumps 7.7.1 MSBR Primary-Salt Pump 7.7.2 Pump Program for the Molten-Salt Breeder Experiment 7.7.3 MSBE Salt Pump Test Stand 7.7.4 ALPHA Pump 7.8 Remote Welding

102 102 106 106 108 109 109 109

8. MSBR INSTRUMENTATION AND CONTROLS 8.1 Control System Analysis 8.2 Calculations of Neutron Decay After Shutdown 8.2.1 Calculation of the Effect of the Beryllium Photoneutron Reaction on Neutron Density After Shutdown 8.2.2 Calculation of Neutron Density Following Loss of Primary Flow 8.3 Dynamic Analysis of MSBR Steam Generator 8.4 High-Temperature Resistance Thermometer Evaluation

113 113 115

9. HEAT TRANSFER AND THERMOPHYSICAL PROPERTIES 9.1 Heat Transfer 9.2 Thermophysical Properties 9.2.1 Thermal Conductivity 9.3 Mass Transfer to Circulating Bubbles

119 119 122 122 124

115 115 116 116

PART 3. CHEMISTRY 10. CHEMISTRY OF THE MSRE 10.1 A Material Balance for the MSRE Fuel Salt 10.2 MSRE Fuel Circuit Corrosion Chemistry 10.3 Adjustment of U3+/ÎŁU Concentration of the MSRE Fuel Salt 10.4 Examination of Simulated MSRE Fuel Mixture for Foam-Producing Properties 10.5 Foaming Behavior in Molten Salts

129 129 130 133 135 137

11. FISSION PRODUCT BEHAVIOR 11.1 Fission Product Behavior in the MSRE 11.1.1 Examination of Graphite Surveillance Specimens 11.1.2 Distribution of Fission Products in the MSRE 11.1.3 Fission Product Inventory During 233U Operation 11.1.4 Response of 95Nb Activity to Fuel Redox Chemistry 11.1.5 MSRE Off-Gas Analyzer-Sampler 11.1.6 Examination of Material Recovered from MSRE Off-Gas Line 11.2 Fission Product Volatilization Tests 11.2.1 Chemical Probe Tests 11.2.2 Electric Charge of the Radioactive Aerosols 11.2.3 Electron Microscope Tests 11.2.4 Aerosol Deposition from a Helium Stream 11.2.5 Closed Tube Diffusion Tests 11.2.6 Volatilization of MSRE Salt in the Absence of Radioactivity 11.2.7 Summary and Interpretation of Hot-Cell Test Results 11.2.8 Attempt to Sample Foam in Pump Bowl 11.3 Laboratory Tests on Aerosol Formation Over Molten Salts and Transfer of Niobium from Salt to Bismuth 11.4 The Chemistry of the Noble Fission Product Fluorides 11.4.1 Molybdenum Fluoride Synthesis, Characterization, and Stability 11.4.2 Mass Spectrometric Studies of Fluorides

138 138 138 138 138 139 140 143 145 145 148 148 148 150 150 151 151 153 157 157 159

12. PHYSICAL CHEMISTRY OF MOLTEN SALTS 12.1 CeF3 Solubility in Molten Mixtures of LiF, BeF2, and ThF4 12.2 Correlation of CeF3 Solubility with Solvent Composition 12.3 Zone Melting of Fluoride Salts 12.3.1 Phase Behavior 12.3.2 Zone Melting 12.3.3 Cyclic Slow Cooling 12.3.4 Cerium 12.4 Behavior of CeF3 in the Fractional Crystallization of ThF4 from LiF-BeF2 -ThF4 Melts 12.5 Properties of the Alkali Fluoroborates 12.5.1 Phase Relations in Fluoroborate Systems 12.5.2 The System Na-KF-BF3 12.5.3 The System KF-KBF4 12.5.4 The System NaBF4-KBF4 12.5.5 The System NaF-NaBF4 12.6 Limits of Miscibility in Molten Salt Systems: KBF4-LiF, Li2BeF4-KI, and Li2BeF4-KBF4 12.6.1 The System KBF4-LiF 12.6.2 The System Li2BeF4-KI 12.6.3 The System Li2BeF4- KBF4 12.7 Solubility of Thorium Metal in Molten Lithium Fluoride-Thorium Fluoride Mixtures 12.8 The Crystal Structure of KBF4 12.9 Densities of Molten Salts 12.10 Spectroscopy of Fluoride Media 12.10.1 The Diamond-Windowed Cell 12.10.2 Salt Purification for Fluoride Spectroscopy 12.11 The Distribution of U4+ Between Molten LiF-BeF2 ThF4-UF4 and a (U-Th)O2 Solid Solution 12.12 An Ni-NiO-BeO Electrode as a Reference Electrode in Molten Fluorides 12.13 Emf Measurements with Concentration Cells with Transference in Molten Mixtures of LiF and BeF2 12.14 Electrical Conductance of Molten KNO3 12.15 Electrical Conductance of Molten Beryllium Fluoride

163 163 164 166 167 168 168 168 168 169 169 170 170 171 171 171 171 172 172 172 173 174 175 175 175

13. CHEMISTRY OF MOLTEN-SALT REACTOR FUEL REPROCESSING TECHNOLOGY 13.1 Simultaneous Extraction of Zirconium and Uranium and of Zirconium and Protactinium 13.2 Protactinium Studies in the High Alpha Molten-Salt Laboratory 13.3 Further Studies of the Reductive Extraction of Protactinium from Single-Fluid MSBR Fuel Salt by Thorium in Molten Bismuth 13.4 Reductive Extraction of Rare Earths from Molten Mixtures of LiF, BeF2, and ThF4 into Bismuth 13.5 Metal Phases Other than Bismuth for Rare-Earth Extraction 13.6 Separation of Cerium from Thorium in Bismuth by Cold Zone Deposition of Thorium Bismuthide 13.7 Extraction of Thorium by Electrolytic Reduction into Flowing Liquid Lead from Molten Mixtures of LiF, BeF2, ThF4, and Rare-Earth Fluorides

187 187 188

14. DEVELOPMENT AND EVALUATION OF ANALYTICAL METHODS FOR MOLTEN-SALT REACTORS 14.1 Determination of Oxide in MSRE Fuel 14.2 Determination of the Oxidation State of Constituents of MSRE Fuel 14.2.1 Determination of Total Reducing Power of MSR Salts 14.2.2 Determination of U(III) in Radioactive MSRE Fuel by a Hydrogen Reduction Method 14.2.3 Voltammetric Determination of U(IV)/U(III) Ratios in MSRE Fuel 14.3 Emf, Voltammetric, and Spectrophotometric Measurements on the

176 178 180 182 184

189 191 192 193 195 197 197 197 197 199 200

U(IV)/U(III) Couple in Molten LiF-BeF2 -ZrF4 14.4 Emf Measurements in Molten Fluorides 202 14.5 Development of a Molten-Salt Spectrophotometric Facility for Hot-Cell Use 14.6 Absorption Spectra of 3d Transition-Metal Ions in Molten LiF-BeF2 14.7 Effect of Reductants on Metal-Fluoride-Salt Wetting Behavior 14.8 Determination of Contaminants in the Blanket Gas of NaBF4 Tests 14.9 Determination of Bismuth in MSRP Salts 14.9.1 Polarography 14.9.2 Spectrophotometry 14.9.3 Emission Spectrography 14.9.4 Polarographic Shipping 14.9.5 Isotopic Exchange

201 202 204 205 205 208 208 208 208 208 208

PART 4. MOLTEN-SALT IRRADIATION EXPERIMENTS 15. MOLTEN-SALT CONVECTION LOOP IN ORR 15.1 Studies of Surface Wetting of Graphite by Molten Salt

210 210

PART 5. MATERIALS DEVELOPMENT 16. MSRE SURVEILLANCE PROGRAM 16.1 Examination of Particles Removed from Pump Bowl with Magnets 16.1.1 Observations on Particles from Magnet FP-15-53 16.1.2 Observations on Particles from Magnet FP-16-2

211 211 212 213

17. GRAPHITE STUDIES 17.1 Fundamental Studies of Radiation Damage Mechanisms in Graphite 17.2 Graphitization Chemistry and Binder System Development 17.3 Hot Pressing of Graphite Pellets Using Various Binders 17.4 Procurement and Physical Property Measurements on New Grades of Graphite 17.5 Physical Properties of Graphites 17.6 X-Ray Studies 17.7 Electron Microscopy of Graphite 17.8 Gas Impregnation of Graphite with Carbon 17.9 Graphite Irradiation in HFIR 17.10 Calculation of Lifetime and Induced Stresses in MSBR Cores

214 214 215 216 217 219 219 221 221 224 229

18. HASTELLOY N 18.1 Influence of Titanium and Carbon on the Mechanical Properties of Nickel-Base Alloys 18.2 Aging of Modified Hastelloy N 18.3 Influence of Irradiation Temperature on the Creep-Rupture Properties of Hastelloy N 18.4 Electron Microscopy Studies 18.5 Measurement of Residual Stresses in Hastelloy N Welds 18.6 Corrosion Studies 18.6.1 Fuel Salts 18.6.2 Fertile-Fissile Salts 18.6.3 Blanket Salts 18.6.4 Coolant Salts 18.6.5 Comparison of the Kinetic Behavior of Nickel- and Iron-Based Alloys in Molten Fluoride Salts 18.7 Forced Convection Loop 18.8 Oxidation of Hastelloy N

232 232 233 235 240 242 243 243 243 245 246 248 253 254

19. SUPPORT FOR CHEMICAL PROCESSING 19.1 Graphite-Hastelloy N Transition Joint Development 19.2 Development of Corrosion-Resistant Brazing Alloys for Molybdenum 19.3 Examination of Mo-TZM Capsule 19.4 Bismuth Corrosion Studies

261 261 261 262 264

20. SUPPORT FOR COMPONENTS DEVELOPMENT PROGRAM 20.1 Remote Welding Development 20.2 Thermal Cycling Tests on Coated Bearing Specimens

267 267 267

PART 6. MOLTEN-SALT PROCESSING AND PREPARATION 21. FLOWSHEET ANALYSIS 21.1 Proposed Reductive Extraction Processing Flowsheet for a Single-Fluid MSBR 21.2 Protactinium Removal from a Single-Fluid MSBR 21.3 Removal of Rare Earths from a Single-Fluid MSBR 21.4 Material Balance Calculations 21.4.1 MSBR Nuclear Data Compilation 21.4.2 MSBR Material Balance Calculations 21.4.3 MSBR Processing Plant Design Calculations

270 270 272 273 275 275 275 277

22. MEASUREMENT OF DISTRIBUTION COEFFICIENTS IN MOLTEN-SALT-METAL SYSTEMS 22.1 Extraction of Uranium, Zirconium, Protactinium, and Plutonium from Single-Fluid MSBR Fuels 22.2 Solubility of Protactinium in Bismuth 22.3 Extraction of Thorium and Rare Earths from Single-Fluid MSBR Fuels 22.4 Metal Transfer Process Studies 22.5 Effect of Other Components on the Solubility of Thorium in Bismuth

279

23. ENGINEERING DEVELOPMENT OF PROCESS OPERATIONS 23.1 Electrolytic Cell Development 23.1.1 Quartz Static Cell Experiments 23.1.2 All-Metal Static Cell Experiment 23.2 Reductive Extraction Engineering Studies 23.3 Simulated Molten-Salt-Liquid-Bismuth Contactor Studies 23.4 Design of a Continuous Electrolytic Cell Testing System 23.5 Experimental Facilities for Reductive Extraction Development Work

288 288 288 291 291 293 296 297

24. DISTILLATION OF MSRE FUEL CARRIER SALT

298

ORGANIZATION CHART

301

279 282 284 285 287

ORNL-4449 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending August 31, 1969 INTRODUCTION

ix

SUMMARY

xi PART 1. MOLTEN-SALT REACTOR EXPERIMENT

1. MSRE OPERATIONS 1.1 Chronological Account of Operations and Maintenance 1.2 Operations Analysis 1.2.1 Reactivity Balance 1.2.2 Reactivity Effects of Graphite Distortion 1.2.3 Gas in the Fuel System 1.2.4 Diagnosis by Noise Analysis 1.2.5 Fission Product Distributions in Fuel System 1.2.6 Salt Transfer to Overflow Tank 1.2.7 Coolant Salt Flow Rate 1.2.8 Radiation Heating 1.2.9 Service Life 1.2.10 Heat Transfer 1.3 Equipment 1.3.1 New Irradiation-Specimen Array for Core 1.3.2 Salt Samplers 1.3.3 Control Rods and Drives 1.3.4 Off-Gas System 1.3.5 Component Cooling System 1.3.6 Containment and Ventilation 1.3.7 Heaters and Electrical System 1.3.8 Oil Systems for Salt Pumps 1.3.9 Radiator and Main Blowers 1.4 Remote Maintenance

1 1 4 4 5 6 10 11 12 12 13 13 14 14 14 15 16 17 19 19 19 20 20 20

2. MSRE REACTOR ANALYSIS 2.1 Introduction 2.2 Definition of Average Reaction Cross Sections 2.3 Results of Revised Cross-Section Calculations 2.4 Effects on Other MSRE Neutronic Characteristics

22 22 22 23 25

3. COMPONENT DEVELOPMENT 3.1 Freeze-Flange Thermal-Cycle Test 3.1.1 Facility Operation Problems 3.1.2 Inspection of the Flanges 3.2 Pumps 3.2.1 Mark 2 Fuel Pump 3.2.2 Oil Pump Endurance Test 3.3 MSRE Remote Gamma Spectrometer 3.3.1 Description of the Equipment 3.3.2 Test Program

27 27 27 27 29 29 31 31 31 33

3.4 Noble-Metal Migration in the MSRE 4. INSTRUMENTS AND CONTROLS 4.1 Development of Reactor Diagnosis Using Noise Analysis 4.2 MSRE Operating Experience 4.3 Control System Design

33 36 36 37 37

PART 2. MSBR DESIGN AND DEVELOPMENT 5. DESIGN 5.1 General 5.2 Plant Layout 5.3 Seismic Review of MSBR Plant Conceptual Design 5.4 Cooling Requirements for Waste Storage Pit 5.5 Primary Salt Drain Tank 5.6 Primary-Salt-Drain-Tank Operation and Afterheat Removal System 5.7 Gamma Heating in MSBR Heat Exchangers

39 39 43 49 51 52 55 56

6. REACTOR PHYSICS 6.1 Physics Analysis of MSBR 6.1.1 One-Fluid MSBR Reference Design: Two-Dimensional Calculation 6.1.2 MSBR Nuclear Design Studies 6.1.3 Alternate MSBR Design Studies 6.1.4 Gamma and Neutron Heating in MSBR 6.1.5 MSBR Dynamics and Control 6.2 Physics Analysis of MSBE 6.2.1 MSBE Design Studies 6.3 MSR Experimental Physics 6.3.1 235U Capture-to-Absorption Ratio in the Fuel of the MSRE 6.3.2 233U Capture-to-Absorption Ratio in the Fuel of the MSRE 6.3.3 233U Capture-to-Absorption Ratio in Encapsulated Samples in the MSRE

59 59 59 60 61 63 66 69 69 70 70 72 72

7. SYSTEMS AND COMPONENTS DEVELOPMENT 7.1 Bubble Generator 7.2 Molten-Salt Steam Generator 7.2.1 Steam-Generator Industrial Program 7.2.2 Steam-Generator Tube Test Stand 7.3 Sodium Fluoroborate Circulating Test Loop 7.3.1 Corrosion-Product Deposition 7.3.2 Gas System Studies 7.4 MSBE Pumps 7.4.1 MSBE Salt Pump Procurement 7.4.2 MSBE Salt Pump Test Stand 7.4.3 ALPHA Pump 7.5 Remote Welding

73 73 73 74 74 74 74 75 77 77 78 78 79

8. MSBR INSTRUMENTATION AND CONTROLS 8.1 Control System Analysis 8.2 Dynamic Analysis of MSBR Steam Generator

83 83 83

9. HEAT AND MASS TRANSFER AND THERMOPHYSICAL PROPERTIES 9.1 Heat Transfer 9.2 Thermophysical Properties 9.3 Mass Transfer to Circulating Bubbles

85 85 89 93

PART 3. CHEMISTRY 10. CHEMISTRY OF THE MSRE 10.1 Composition of the MSRE Fuel Salt 10.2 A Material Balance for Plutonium in the MSRE Fuel Salt 10.3 Some Factors in Gas Behavior in the MSRE Fuel System

96 96 98 102

11. FISSION PRODUCT BEHAVIOR 11.1 Examination of the Fourth Set Surveillance Specimens from the MSRE 11.1.1 Examination of Graphite 11.1.2 Radiochemical Analyses of the Graphite 11.1.3 Penetration of the Graphite by Uranium 11.1.4 Radiochemical Analyses and Deposition of Fission Products on Hastelloy N from the Core of the MSRE 11.2 Samples from MSRE Pump Bowl 11.3 Examination of Materials from MSRE Off-Gas Lines 11.4 The Surface Tension of the MSRE Fuel and Flush Salts 11.5 Niobium Reduction Potentials 11.6 Noble-Metal Fission Product Chemistry 11.6.1 Synthesis and Stability of Molybdenum Fluorides 11.6.2 Kinetics of MoF3 Disproportionation in Molten 2LiF-BeF2 11.63 Mass Spectrometric Studies 11.6.4 Infrared Spectroscopy

104 104 104 104 106

12. PROPERTIES OF THE ALKALI FLUOROBORATES 12.1 Melting Points and Solid Transition Temperatures of Alkali Fluoroborates 12.2 Densities and Molar Volumes of Molten Fluoroborates 12.3 Predicted Volume Changes in Crystalline Alkali Fluoroborates 12.4 Refractive Indices and Electronic Polarizabilities in Crystalline Alkali Fluoroborates 12.5 Decomposition Pressures and Sยบ298 of LiBF4 12.6 X-Ray Crystal Parameters of LiBF4 12.7 Mixing Reactions of MSBR Fuel and Coolant Salts 12.8 Phase Relations in the System NaF-KF-BF3 12.9 Preparation of Pure NaBF4 12.10 Attempted Synthesis of NaBF3OH

122 122 122 123 124 125 127 127 128 129 130

13. PHYSICAL CHEMISTRY OF MOLTEN SALTS 13.1 Phase Relations in the System LiF-BeF2-CeF3 13.2 Heterogeneous Equilibria Between Cerium-Containing Melts and Various Oxide Phases 13.3 Liquidus Temperatures in the System LiF-BeF2-ThF4 13.4 The Solubility of Thorium in Thorium Tetrafluoride 13.5 Potentiometric Determination of the U4+/U3+ Ratio in Molten Fluorides 13.6 Refinement of the UF3 Spectrum 13.7 EMF Measurements with Concentration Cells with Transference in Molten Mixtures of LiFand BeF2 13.8 Improved Determination of Electrical Conductance of LiF-BeF2 (66-34 mole %) 13.9 Electrical Conductivities of Low-Melting NaF-BeF2 Mixtures 13.10 Viscosity of Molten Salts 13.11 Density of Molten Fluorides of Reactor Interest 13.12 Room-Temperature Densities and Estimated Density Change, Upon Melting, of MSBR Fuel and Coolant Salts

131 131 131 135 135 135 137

14. CHEMISTRY OF MOLTEN-SALT REACTOR FUEL REPROCESSING TECHNOLOGY 14.1 Reductive Extraction of Protactinium at High Concentrations (2000 ppm Level) from MSBR Fuel Solvent Salt (LiF-BeF2-ThF4, 72-16-12 mole %) into Molten Bismuth

149

107 107 109 109 112 113 113 115 116 121

138 141 142 144 145 146

149

14.2 The Separation of Zirconium from Uranium in Bismuth Solutions by Platinide Precipitation 14.3 Bismuth-Magnesium Mixtures as Rare-Earth Extractants 14.4 Reductive Extraction of Rare Earths from Molten LiF-BeF2-ThF4 (72-16-12 mole %) into Tin and Aluminum-Tin Mixtures at 600째C 14.5 Extraction of Thorium from Processed MSBR Fuel Salt into Molten Lead 15. DEVELOPMENT AND EVALUATION OF ANALYTICAL METHODS FOR MOLTEN-SALT REACTORS 15.1 Determination of Oxide in MSRE Fuel 15.2 Voltammetric Determination of U(IV)/U(III) Ratios in MSRE Fuel 15.3 Computer-Operated Voltammetric U(IV)/U(III) Ratio Determination 15.4 Electroanalytical Studies in Molten Fluorides 15.5 Spectral Studies of Superoxide Ion in Molten Fluoride Salts 15.6 Hot-Cell Spectrophotometric Facility 15.7 Removal of Oxide from NaBF4 15.8 Determination of Bismuth in MSRP Salts 15.8.1 Emission Spectrography 15.8.2 Inverse Polarography

151 152 152 154 156 156 156 157 158 159 160 161 162 162 162

PART 4. MOLTEN-SALT IRRADIATION EXPERIMENTS PART 5. MATERIALS DEVELOPMENT 16. MSRE SURVEILLANCE PROGRAM 16.1 Removal and Examination of Surveillance Samples 16.2 Properties of the Hastelloy N Surveillance Samples

165 165 168

17. GRAPHITE STUDIES 17.1 Procurement of New Graphites 17.2 Graphite Fabrication 17.3 X-Ray Studies 17.4 Electron Microscopy of Graphite 17.5 Gas Impregnation of Graphite with Carbon 17.6 Graphite Irradiations in HFIR 17.7 The Energy Dependence of Neutron Damage in Graphite 17.8 Fundamental Studies of Radiation Damage Mechanisms in Graphite 17.9 Macroscopic Damage Models

171 171 171 172 174 174 175 177 179 180

18. HASTELLOY N 18.1 Aging of Titanium-Modified Hastelloy N 18.2 Statistical Treatment of Aging Data for Hastelloy N 18.3 Development of a Modified Hastelloy N 18.4 Electron Microscope Studies 18.5 Corrosion Studies 18.5.1 Fuel Salts 18.5.2 Fertile-Fissile Salts 18.5.3 Blanket Salts 18.5.4 Coolant Salts 18.5.5 Corrosion Meter 18.5.6 Corrosion Status 18.6 Forced Convection Loop (MSR-FCL-1) 18.7 Steam Corrosion of Hastelloy N

182 182 183 184 193 195 195 195 200 200 202 202 203 205

19. SUPPORT FOR CHEMICAL PROCESSING 19.1 Chemical Vapor-Deposited Coatings 19.2 Development of Bismuth-Resistant Brazing Filler Metals for Joining Molybdenum

210 210 211

20. SUPPORT FOR COMPONENTS DEVELOPMENT PROGRAM 20.1 Remote Welding Studies

213 213

PART 6. MOLTEN-SALT PROCESSING AND PREPARATION 21. MEASUREMENT OF DISTRIBUTION COEFFICIENTS IN MOLTEN-SALT-METAL SYSTEMS 21.1 Extraction of Transuranium Elements from Single-Fluid MSBR Fuels 21.2 Extraction of Rare Earths and Thorium from Single-Fluid MSBR Fuels 21.3 Coprecipitation of Rare Earths with Thorium Bismuthide 21.4 Dissolvability and Solubility of PuF3 in LiF-BeF2 (66-34 mole %)

215 215 216 217 219

22. FLOWSHEET ANALYSIS 22.1 Isolation of Protactinium 22.1.1 Steady-State Performance for the Case of MSBR Fueled with Uranium 22.1.2 Transient Performance for the Case of MSBR Fueled with Uranium 22.1.3 Steady-State Performance for the Case of MSBR Fueled with Plutonium 22.2 Removal of Rare Earths from a Single-Fluid MSBR 22.3 Stripping of ThF4 from Molten Salt by Reductive Extraction 22.4 MSBR Processing Plant Material and Energy Balance Calculations

220 220 220 221 224 225 226 226

23. ENGINEERING DEVELOPMENT OF PROCESS OPERATIONS 23.1 Reductive Extraction Engineering Studies 23.2 Electrolytic Cell Development 23.2.1 Static Cell Experiments 23.2.2 Flow Electrolytic Cell Facility 23.2.3 Analysis of Mass Transfer in Electrolytic Cells 23.3 Salt-Metal Contactor Development 23.4 Effect of Axial Mixing on Extraction Column Height 23.5 Axial Mixing in Bubble Columns

229 229 230 230 233 235 236 238 240

24. DISTILLATION OF MSRE FUEL CARRIER SALT

241

25. DESIGN STUDIES FOR SALT PROCESSING 25.1 Heat Transfer Through the Frozen Salt Walls of an Electrolytic Cell 25.2 Design of a Continuous Salt Purification System 25.3 Design and Preparation of 239PuF3 Capsules for Small Refueling Additions to the MSRE

244 244 244 245

ORNL-4548 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending February 28, 1970 INTRODUCTION

xi

SUMMARY

xiii PART 1. MOLTEN-SALT REACTOR EXPERIMENT

1. MSRE OPERATIONS 1.1 Chronological Account of Operations and Maintenance 1.2 Operations Analysis 1.2.1 Reactivity Balance 1.2.2 Xenon Poisoning 1.2.3 Dynamics Testing 1.2.4 Operational Diagnosis by Noise Analysis 1.2.5 Tritium 1.2.6 Fission Product Distribution in the Fuel System 1.2.7 Graphite Samples Exposed in Fuel Pump 1.2.8 Evaluation of Leak in Primary System 1.2.9 Salt Transfer to the Overflow Tank 1.2.10 Radiation Heating 1.2.11 System Heat Balance 1.2.12 Heat Transfer in Primary Heat Exchanger 1.2.13 Thermal Cycle History 1.3 Equipment 1.3.1 Salt Samplers 1.3.2 Control Rods and Drives 1.3.3 Off-Gas Systems 1.3.4 Component Cooling System 1.3.5 Containment and Ventilation 1.3.6 Heaters and Electrical System 1.3.7 Oil Systems for Salt Pumps 1.3.8 Radiator and Main Blowers 1.4 Remote Maintenance 1.5 Final Shutdown and Standby Status 1.6 Preparations for Inspection

1 1 5 5 6 7 7 9 11 13 14 14 15 15 17 17 18 18 20 20 22 22 22 23 23 23 24 25

2. REACTOR ANALYSIS 2.1 Introduction 2.2 Extensions of MSRE Core Physics Calculations to the Use of XSDRN-CITATION Programs 2.3 Evaluation of Long-Term Reactivity Behavior During Operation with 235U

26 26 26 30

3. COMPONENT DEVELOPMENT 3.1 Freeze-Flange Thermal-Cycle Test 3.1.1 Facility Operation Problems 3.1.2 Inspection of the Flanges 3.2 Pumps 3.2.1 Mark 2 Fuel Pump 3.2.2 Oil Pump Endurance Test

34 34 34 34 35 35 36

3.3 Development of Analytical Model for 135Xe Poisoning in the MSRE 4. INSTRUMENTS AND CONTROLS 4.1 MSRE Operating Experience 4.2 Control System Design 4.3 MSRE On-line Computer

37 39 39 40 40

PART 2. MSBR DESIGN AND DEVELOPMENT 5. DESIGN 5.1 Single-Fluid MSBR Design Study 5.2 MSBR Primary Salt Storage Tank 5.3 Startup and Shutdown Procedures 5.3.1 Startup Procedures 5.3.2 Normal Shutdown 5.4 Designs for First-Generation Molten-Salt Power Reactors 5.4.1 General 5.4.2 Large MSRE-Type Reactor 5.4.3 Spherical Reactor with Graphite Ball Bed 5.5 Bayonet-Tube Heat Exchangers 5.6 Distribution of Tritium in an MSBR

41 41 46 46 46 48 48 48 49 49 54 54

6. REACTOR PHYSICS 6.1 Physics Analysis of MSBR 6.1.1 Single-Fluid MSBR Reference Design 6.1.2 Designs for First-Generation Molten-Salt Power Reactors 6.1.3 Reactivity Coefficients 6.1.4 Control Rod Worth 6.2 MSR Experimental Physics 6.2.1 Indication of Integrated Power by 235U Depletion

58 58 58 60 63 64 65 65

7. SYSTEMS AND COMPONENTS DEVELOPMENT 7.1 Molten-Salt Steam Generator 7.1.1 Steam Generator Industrial Program 7.1.2 Steam Generator Tube Test Stand 7.2 Sodium Fluoroborate Test Loop 7.2.1 Salt Leak from Pressure Transmitter 7.2.2 Gas-System Studies 7.3 MSBR Pumps 7.3.1 MSBE Salt Pump Procurement 7.3.2 MSBE Salt Pump Test Stand 7.3.3 ALPHA Pump 7.4 Remote Welding

67 67 67 67 69 69 70 72 72 72 74 74

8. MSBR INSTRUMENTATION AND CONTROLS 8.1 Control System Analysis

79 79

9. HEAT AND MASS TRANSFER AND THERMOPHYSICAL PROPERTIES 9.1 Heat Transfer 9.2 Thermophysical Properties 9.3 Mass Transfer to Circulating Bubbles

87 87 89 90

PART 3. CHEMISTRY 10. CHEMISTRY OF THE MSRE 10.1 Corrosion of the MSRE Fuel Salt Circuit

93 93

10.2 Relationship of the Distribution of 95Nb in the MSRE to the Presence of Uranium Trifluoride in the Fuel Salt 10.3 Power Output of the MSRE Based on the Isotopic Composition of Plutonium 10.4 Isotopic Composition of Uranium During 233U Operations 10.5 Surface Tension and Wetting Behavior of the MSRE Fuel and Coolant Salts

96 98 100 100

11. FISSION PRODUCT BEHAVIOR 11.1 Examination of the Fourth Set of Surveillance Specimens from the MSRE 11.1.1 Radiochemical Analyses of the Graphite 11.1.2 Radiochemical Analyses of Fission Product Deposition on Metal 11.1.3 Fission Product Distribution in the MSRE 11.2 Fission Product Distribution in MSRE Pump Bowl Samples 11.3 Investigations of the Behavior of Fission Product Niobium 11.4 Noble Metal Fission Product Chemistry 11.4.1 Introduction 11.4.2 Synthesis 11.4.3 Niobium and Molybdenum Fluoride Solutions in Molten Li2BeF4 11.4.4 Mass Spectroscopy of Molybdenum and Ruthenium Fluorides

104 104 104 108 110 111 118 123 123 124 124 126

12. PROPERTIES OF THE ALKALI FLUOROBORATES 12.1 Phase Equilibria in the Alkali Metal Fluoride-Metal Fluoroborate Binary Systems: The System RbF-RbBF4 12.2 Solubility of Na3CrF6 in Sodium Tetrafluoroborate Melts 12.3 Preparation of Pure Sodium Tetrafluoroborate 12.4 Investigation of Oxidation of Metals by Fluoroborate Coolant 12.5 Boron Trifluoride Pressure over Fluoroborate Coolant Salt Admixed with MSBR Fuel Salt 12.6 Heat Content of Alkali Metal Fluoroborates

133

13. PHYSICAL CHEMISTRY OF MOLTEN SALTS 13.1 Equilibration of Rare-Earth-Containing Molten Fluorides with Various Solids 13.2 The Oxide Chemistry of Plutonium in Molten Fluorides 13.3 The CeF3-ThF4 System 13.4 Equilibrium Phase Relationships in the System LiF-BeF2-CeF3 13.5 An Investigation of Possible Polymorphic Transitions in Uranium Tetrafluoride 13.6 Estimation of Activity Coefficients in LiF-BeF2-ThF4 Melts 13.7 Estimation of Activity Coefficients of Alkaline Earths in Molten Bismuth and as Chlorides or Fluorides 13.8 Potentiometric Studies in Molten Fluorides 13.9 Electrical Conductivities and Ionic Mobilities in the Molten LiF-BeF2 System 13.10 Electrical Conductivities of Proposed MSBR Fuel Compositions in the LiF-BeF2-ThF4 System 13.11 Determination of Liquidus Temperatures in the LiF-BeF2 System from EMF Measurements of Transference Cells 13.12 Coordination Effects on U(IV) Spectra in Fluoride Melts 13.13 Hydrogen Behavior in Molten-Salt Reactor Systems 13.14 Crystal Structure of the Complex Fluoride (Na,Li)7Th6F31

140 140 142 145 147 148 149

14. CHEMISTRY OF MOLTEN-SALT REACTOR FUEL REPROCESSING TECHNOLOGY 14.1 Distribution of Cerium, Europium, and Strontium Between Bismuth and Lithium Chloride 14.2 Extraction of Cesium from Lithium Chloride into Bismuth by Reduction with Lithium at 650째C 14.3 Removal of Chloride from Simulated MSBR Fuel Solvent by Reaction with Anhydrous Hydrogen Fluoride 14.4 Calculated Behavior of Sodium, Rubidium, and Cesium in the Molten-Salt Breeder Reactor Reprocessing Plant 14.5 Reduction of Uranium and Protactinium with Titanium

171 171

133 134 134 135 136 138

153 154 156 159 161 165 167 168

172 173 174 176

14.6 Bismuth-Gold Alloys as Extractants for Rare Earths and Thorium 14.7 Bismuth Platinum Solutions for the Extraction of Fission Products from MSBR Salt 14.8 Extraction of Cerium and Thorium from LiF-BeF2 (66-34 mole %) into Bismuth at 600°C 15. DEVELOPMENT AND EVALUATION OF ANALYTICAL METHODS FOR MOLTEN-SALT REACTORS 15.1 Determination of Oxide in MSRE Salt 15.2 Voltammetric Determination of [U3+]/[ΣU] Ratios in MSRE Fuel 15.3 Spectral Studies of MSRE Salts 15.4 Tritium in the Effluent Gases of the MSRE 15.5 Reference Electrode Studies in Molten Fluorides 15.6 Removal of Oxide from NaBF4 15.7 A Preliminary Study of Volatile AlCl3 Complexes

176 176 178 180 180 180 180 183 184 185 185

PART 4. MOLTEN-SALT IRRADIATION EXPERIMENTS PART 5. MATERIALS DEVELOPMENT 16. MSRE SURVEILLANCE PROGRAM 16.1 Properties of Hastelloy N Samples Removed from the MSRE

188 189

17. GRAPHITE STUDIES 17.1 Fundamental Studies of Radiation Damage Mechanisms in Graphite 17.2 Procurement of New Grades of Graphite 17.3 General Physical Property Measurements 17.4 Graphite Fabrication 17.4.1 Characterization of Materials 17.4.2 Fabrication by Hot Pressing 17.4.3 Fabrication by Isostatic Pressing 17.4.4 Conclusions 17.5 Measurement of the Thermal Conductivity of Graphite 17.6 X-Ray Studies 17.7 Electron Microscopy of Graphite 17.8 Gas Impregnation of Graphite 17.9 HFIR Irradiation Program 17.10 Irradiation Behavior of Pyrolytic Carbons 17.11 Calculation of Lifetime and Induced Stresses in MSBR Graphite Cores

200 200 201 201 203 203 203 204 205 205 207 209 209 213 215 218

18. HASTELLOY N 18.1 Aging of Modified Alloys 18.2 Effect of Carbon and Titanium on Postirradiation Properties 18.3 Effects of Irradiation at 760°C on the Creep-Rupture Properties of Modified Hastelloy N 18.4 Electron Microscopy of Modified Hastelloy N Alloys 18.5 Weldabdity of Commercial Alloys 18.6 Corrosion Studies 18.6.1 Fuel Salts 18.6.2 Fertile-Fissile Salts 18.6.3 Blanket Salts 18.6.4 Coolant Salts 18.6.5 Summary of Corrosion Studies 18.7 Fluoroborate Purity Test 18.8 Forced-Convection Loop MSR-FCL-1 18.8.1 Metallurgical Analysis 18.8.2 Forced-Convection Loop MSR-FCL-2 18.9 Corrosion of Hastelloy N in Steam

222 222 225 229 231 238 240 240 242 242 242 247 247 247 248 251 252

19. SUPPORT FOR CHEMICAL PROCESSING 19.1 Fabrication Development of Molybdenum Components 19.2 Welding of Molybdenum 19.3 Development of Bismuth-Resistant Brazing Filler Metals for Joining Molybdenum 19.4 Compatibility of Structural Materials with Bismuth 19.5 Chemical Vapor Deposited Coatings 19.6 Scaling Resistance of Carbon Steels

253 253 254 255 256 259 261

20. SUPPORT FOR COMPONENTS DEVELOPMENT PROGRAM 20.1 Remote Welding Development 20.2 Support for Systems and Component Development 20.3 Coated Bearing Specimens

265 265 265 271

PART 6. MOLTEN-SALT PROCESSING AND PREPARATION 21. FLOWSHEET ANALYSIS 21.1 Rare Earth Removal Using the Metal Transfer Process 21.2 Protactinium Isolation Using Fluorination-Reductive Extraction 21.3 MSBR Processing by Fluorination-Reductive Extraction and the Metal Transfer Process

277 277 279 282

22. MEASUREMENT OF DISTRIBUTION COEFFICIENTS IN MOLTEN-SALT-METAL SYSTEMS 22.1 Metal Transfer Process Studies 22.2 Extraction of Barium, Rare Earths, and Thorium from Single-Fluid MSBR Fuels 22.3 Solubility of Bismuth in Single-Fluid MSBR Fuel Salts 22.4 Studies Involving BiF3

289 289 290 292 292

23. ENGINEERING DEVELOPMENT OF PROCESS OPERATIONS 23.1 Reductive Extraction Engineering Studies 23.2 Design of a Processing Materials Test Stand and the First Molybdenum Reductive Extraction Equipment 23.3 Bismuth-Salt Interface Detector 23.4 Contactor Development: Pressure Drop, Holdup, and Flooding in Packed Columns 23.5 Contactor Development: Axial Mixing in Packed Columns 23.6 Axial Mixing in Open Columns 23.7 Demonstration of the Metal Transfer Process for Removing Rare Earths 23.8 Frozen-Wall Fluorinator Development 23.9 Electrolytic Cell Development 23.9.1 Static Cell Experiments 23.9.2 Flow Electrolytic Cell Facility

295 295

24. DISTILLATION OF MSRE FUEL CARRIER SALT

317

25. SYSTEM CALCULATIONS 25.1 MSBR Processing Plant Material and Energy Balance Calculations 25.2 Effect of Chemical Processing on the Nuclear Performance of an MSBR

324 324 325

26. CONTINUOUS SALT PURIFICATION SYSTEM

329

27. DESIGN AND PREPARATION OF 239PuF3 CAPSULES FOR SMALL REFUELING ADDITIONS TO THE MSRE

332

298 300 302 304 307 309 309 311 312 316

ORNL-4622 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending August 31, 1970 INTRODUCTION SUMMARY PART 1. MOLTEN-SALT REACTOR EXPERIMENT 1. MSRE OPERATIONS 1.1 Chronological Account 1.2 Operations Analysis 1.2.1 Gamma Spectrometry 1.2.2 Noble-Metal Migration 1.2.3 Radiation Heating 1.2.4 Fluorine Evolution from Frozen Salt

1 1 2 2 2 4 4

2. COMPONENT DEVELOPMENT 2.1 Freeze-Flange Thermal Cycle Test 2.2 Pumps 2.2.1 Mark 2 Fuel Pump 2.2.2 Oil Pump Endurance Test

6 6 6 6 6

PART 2. MSBR DESIGN AND DEVELOPMENT 3. DESIGN 3.1 Single-Fluid 1000-MW(e) MSBR Design Study Report 3.2 Molten-Salt Demonstration Reactor Design Study 3.2.1 Introduction 3.2.2 General Description 3.2.3 Buildings and Containment 3.2.4 Reactor 3.2.5 Primary Heat Exchangers 3.2.6 Primary Drain Tanks 3.2.7 Fuel Salt Storage Tank 3.2.8 Discard Salt Storage Tanks 3.2.9 Steam System 3.3 Afterheat Temperatures in Empty MSBR Heat Exchangers 3.4 Industrial Study of 1000-MW(e) Molten-Salt Breeder Reactor

8 8 8 8 9 9 16 18 18 21 22 24 24 25

4. REACTOR PHYSICS 4.1 Physics Analysis of MSBR 4.1.1 Fixed-Moderator Molten-Salt Reactor 4.2 MSR Experimental Physics 4.2.1 233U Capture-to-Absorption Ratio in the Fuel of the MSRE

26 26 26 31 31

5. SYSTEMS AND COMPONENTS DEVELOPMENT 5.1 Gaseous Fission Product Removal 5.1.1 Gas Separator

35 35 35

5.1.2 Bubble Generator 5.1.3 Water Test Loop 5.2 Molten-Salt Steam Generator 5.2.1 Steam Generator Industrial Program 5.2.2 Steam Generator Tube Test Stand (STTS) 5.2.3 Molten-Salt Steam Generator Technology Loop (SGTL) 5.2.4 Development Basis for Steam Generators Using Molten Salt as the Heat Source 5.3 Sodium Fluoroborate Test Loop 5.3.1 Water Addition Test 5.3.2 Conclusions 5.4 MSBR Pumps 5.4.1 MSBE Salt Pump Procurement 5.4.2 MSBE Salt Pump Test Stand 5.4.3 ALPHA Pump 5.5 Remote Welding 5.5.1 Operational Prototype Equipment 5.5.2 Cutting Development 5.5.3 Welding Development 5.5.4 External Interest 5.5.5 Design Studies

38 39 39 39 40 40 40 41 41 44 44 44 45 45 45 45 45 47 49 49

6. MSBR INSTRUMENTATION AND CONTROLS

51

7. HEAT AND MASS TRANSFER AND THERMOPHYSICAL PROPERTIES 7.1 Heat Transfer 7.2 Thermophysical Properties 7.3 Mass Transfer to Circulating Bubbles

53 53 54 57

PART 3. CHEMISTRY 8. FISSION PRODUCT BEHAVIOR 8.1 Noble Metal Fission Product Behavior 8.2 Short-Term Fission Product Deposition Tests 8.3 Fission Product Deposition on the Fifth Set of Graphite and Hastelloy N Samples from the MSRE Core 8.3.1 Effect of Surface Roughness 8.3.2 Effect of Flow Conditions on Deposition 8.3.3 Comparison of Deposition of Noble Metal Fission Products on Graphite and Hastelloy N 8.3.4 Concentration Profiles of Fission Products in Graphite 8.3.5 Electron Microscope Examination of Particles in the Gas Phase Above Fuel Salt in the MSRE 8.4 A Possible Origin of Smokes and Mists Emitted by MSRE Fuel 8.5 Synthesis of Niobium Fluorides 8.6 Molybdenum and Niobium Fluoride Solutions in Molten Li2BeF4 8.7 Mass Spectroscopy of Niobium Fluorides 8.8 Raman Spectra of Crystalline MoF5 and MoF4

60 60 66

9. PROPERTIES OF THE ALKALI FLUOROBORATES 9.1 Solubility of BF3 Gas in Fluoride Melts 9.2 Studies of Hydrogen Evolution and Tritium Exchange in Fluoroborate Coolant Salt 9.3 Reaction of Water with the Sodium Fluoride-Sodium Tetrafluoroborate Eutectic 9.4 Raman Spectra of Molten NaBF4 and NaF-NaBF4 to 606째C 9.5 Electronic Polarizability of the Tetrafluoroborate Ion and Various Gaseous Halide Molecules as Compared with the Free (Gaseous) Halide Ions

78 78 79 80 82

68 68 68 69 69 70 70 71 71 73 74

85

9.5.1 The Polarizability of the Tetrafluoroborate Ion 9.5.2 Test of a Recent Theoretical Set of Ion Polarizabilities 9.5.3 Effect of Interaction Between Halide Ions on Polarizability

85 86 87

10. PHYSICAL CHEMISTRY OF MOLTEN SALTS 10.1 Liquidus Temperature of the Salt Mixture LiF-BeF2-ThF4 (70-15-15 mole %) 10.2 Equilibrium Phase Relationships in the System LiF-BeF2-CeF3 10.3 Phase Relationships in the System CeF3-ThF4 10.4 The Instability of PuOF and the Solubility of Pu(III) in MSBR Solvent Salt 10.5 Oxide, Chemistry of Protactinium in MSBR Fuel Solvent Salt 10.6 Entropies of Molten Salts 10.7 All-Metal Conductance Cell for Use in Molten Salts 10.8 Glass Transition Temperatures in NaF-BeF2 Mixtures 10.9 Correlations of Electrical Conductivities in Molten LiF-BeF2-ThF4 Mixtures 10.10 Coordination Effects on U(IV) Spectra in Fluoride Melts

89 89 89 89 91 92 95 98 99 101 103

11. CHEMISTRY OF MOLTEN-SALT REACTOR FUEL TECHNOLOGY 11.1 Removal of Fluoride from Molten LiCl 11.2 Distribution of Sodium and Potassium in the Metal Transfer Process at 650째C 11.3 Removal of Lanthanides from Lithium Chlorides on Zeolites 11.4 Zirconium Platinide as a Removal Agent for Rare Earths

106 106 107 109 110

12. DEVELOPMENT AND EVALUATION OF ANALYTICAL METHODS FOR MOLTEN-SALT REACTORS 12.1 Spectral Studies of MSRE Fuel Samples 12.2 Spectral Studies of Actinide Ions in Molten Fluoride Salts 12.3 Reference Electrode Studies in Molten Fluorides 12.4 Kinetic Studies on the Ni/Ni(II) Couple in Molten LiF-BeF2-ZrF4 12.5 Analytical Studies of NaBF4 Coolant Salt 12.6 In-Line Chemical Analyses

113 113 114 115 115 116 118

PART 4. MATERIALS DEVELOPMENT 13. EXAMINATION OF MSRE COMPONENTS 13.1 Examination of Tubing from the MSRE Radiator 13.2 Examination of Thermocouple Wells from the MSRE Coolant Circuit

119 120 126

14. GRAPHITE STUDIES 14.1 Procurement of New Grades of Graphite 14.2 General Physical Property Measurements 14.3 Graphite Fabrication: Chemistry 14.4 Measurement of Thermal Conductivity of Graphite 14.5 X-Ray Studies 14.6 Reduction of Graphite Permeability by Pyrolytic Carbon Sealing 14.7 HFIR Irradiation Program

134 134 135 135 141 141 142 145

15. HASTELLOY N 15.1 Influence of Titanium on the Strengthening of an Ni-Mo-Cr Alloy 15.2 Effect of Composition on the Postirradiation Mechanical Properties of Modified Hastelloy N 15.3 Comparison of Laboratory and Commercial Heats of Modified Hastelloy N 15.4 Effect of Prior Aging on Irradiation Damage at 760째C 15.5 Weldability of Commercial Alloys 15.6 Mechanical Properties of Unirradiated Commercial Modified Alloys 15.7 Electron Microscope Studies 15.8 Corrosion Studies

149 149 153 156 159 160 161 164 165

15.8.1 Results of Thermal Convection Loop Tests 15.8.2 Fertile-Fissile Salt 15.8.3 Blanket Salt 15.8.4 Coolant Salt 15.8.5 Summary 15.9 Forced-Convection Loop, MSR-FCL-1 15.9.1 Operations 15.9.2 Cold Finger Corrosion Product Trap 15.9.3 Metallurgical Analysis 15.9.4 Forced-Convection Loop MSR-FCL-2 15.10 Corrosion of Hastelloy N in Steam 15.11 Evaluation of Duplex Tubing for Use in Steam Generators

166 168 168 168 171 173 173 174 175 176 178 181

16. SUPPORT FOR CHEMICAL PROCESSING 16.1 Construction of a Molybdenum Reductive Extraction Test Stand 16.2 Fabrication Development of Molybdenum Components 16.3 Welding of Molybdenum 16.4 Development of Bismuth-Resistant Filler Metals for Brazing Molybdenum 16.5 Compatibility of Structural Materials with Bismuth 16.6 Chemically Vapor Deposited Coatings 16.6.1 Tungsten Coatings 16.6.2 Molybdenum Coatings 16.7 Molybdenum Deposition from MoF6

184 184 184 185 189 189 195 195 197 197

17. FLOWSHEET ANALYSIS 17.1 Protactinium Isolation Using Fluorination-Reductive Extraction 17.2 Rare-Earth Removal Using the Metal Transfer Process 17.3 Removal of Uranium from Fuel Salt by Oxide Precipitation

199 200 201 202

18. MEASUREMENT OF DISTRIBUTION COEFFICIENTS IN MOLTEN-SALT-METAL SYSTEMS 18.1 Metal Transfer Process Studies 18.2 Solubility of Neodymium in Li-Bi-Th Solutions 18.3 Solubility of LaOCl in Molten LiCl 18.4 Oxide Precipitation Studies

204 204 207 208 208

PART 5. MOLTEN-SALT PROCESSING AND PREPARATION 19. ENGINEERING DEVELOPMENT OF PROCESS OPERATIONS 19.1 Reductive Extraction Engineering Studies 19.2 Design of a Processing Materials Test Stand and the Molybdenum Reductive Extraction Equipment 19.3 Contactor Development: Pressure Drop, Holdup, and Flooding in Packed Columns 19.4 Contactor Development: Axial Mixing in Packed Columns 19.5 Axial Mixing in Open Bubble Columns 19.6 Demonstration of the Metal Transfer Process for Rare-Earth Removal 19.7 Development of a Frozen-Wall Fluorinator 19.8 Electrolytic Cell Development

211 211

20. CONTINUOUS SALT PURIFICATION SYSTEM

224

212 213 215 216 217 219 220

ORNL-4676 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending February 28, 1971 INTRODUCTION

ix

SUMMARY

xi PART 1. MOLTEN-SALT REACTOR EXPERIMENT

1. POSTOPERATION EXAMINATIONS 1.1 Outline of Program 1.2 Reactor Vessel and Core 1.3 Fuel Pump 1.4 Heat Exchanger 1.5 Leak at Freeze Valve FV-105 1.6 Other Examinations 1.7 Evaluation of Tools and Procedures

1 1 2 6 11 12 12 13

2. FURTHER INVESTIGATIONS 2.1 Test of Coolant Salt Flowmeter and Conclusions 2.2 Inventories of Residual Uranium and Plutonium 2.3 Search for Unrecovered 235U

17 17 18 20

PART 2. MSBR DESIGN AND DEVELOPMENT 3. DESIGN 3.1 Single-Fluid 1000-MWe MSBR Design Study Report 3.2 Molten-Salt Demonstration Reactor Design Study 3.2.1 Introduction 3.2.2 Addition of Third Salt-Circulation Loop 3.2.3 Salt Overflow and Gas Stripping Systems 3.2.4 Primary Drain Tank 3.2.5 Drain Valves for Salt Service 3.2.6 Heat Exchangers 3.2.7 Building and Containment 3.3 Initial Temperature Transients in Empty MSBR "Reference Design" MSBR Heat Exchangers 3.4 The Consequences of Tubing Failure in the MSBR Heat Exchanger 3.5 Tritium Distribution and Control in the MSBR 3.6 Industrial Study of 1000-MWe Molten-Salt Breeder Reactor 3.7 MSBE Design 3.7.1 General 3.7.2 MSBE Core Design 3.7.3 MSBE Primary Heat Exchanger Design

21 21 22 22 22 24 24 25 25 28 32 34 35 36 36 36 36 39

4. REACTOR PHYSICS 4.1 Physics Analysis of MSBR 4.1.1 Single-Fluid MSBR Reference Design 4.1.2 Fixed-Moderator Molten-Salt Reactor 4.2 MSR Experimental Physics 4.2.1 HTLTR Lattice Experiments

41 41 41 43 45 45

5. SYSTEMS AND COMPONENTS DEVELOPMENT 5.1 Gaseous Fission Product Removal 5.1.1 Gas Separator and Bubble Generator 5.2 Gas System Test Facility 5.3 Molten-Salt Steam Generator 5.3.1 Steam Generator Industrial Program 5.3.2 Steam Generator Tube Test Stand (STTS) 5.3.3 Molten-Salt Steam Generator Technology Facility (SGTF) 5.3.4 Development Bases for Steam Generators Using Molten Salt as the Heat Source 5.4 Sodium Fluoroborate Test Loop 5.4.1 Pump Bowl and Rotary Element 5.4.2 BF3 Feed and Salt Level Bubbler Tube 5.5 Coolant Salt Technology Facility 5.6 MSBR Pumps 5.6.1 MSRE Mark 2 Fuel Pump 5.6.2 MSRE Salt Pump Inspection 5.6.3 ALPHA Pump 5.7 Remote Welding 5.7.1 Automatic Controls 5.7.2 Pipe Cleaning Tests

49 49 49 51 51 52 52 52 52 52 53 55 57 58 58 58 59 59 59 60

6. MSBR INSTRUMENTATION AND CONTROLS 6.1 Development of a Hybrid Computer Simulation Model of the MSBR System 6.1.1 Introduction 6.1.2 Steam Generator Model

61 61 61 61

7. HEAT AND MASS TRANSFER AND THERMOPHYSICAL PROPERTIES 7.1 Heat Transfer 7.2 Thermophysical Properties 7.2.1 Wetting Studies 7.2.2 Thermal Conductivity 7.3 Mass Transfer to Circulating Bubbles 7.3.1 Experiment 7.3.2 Theory

64 64 67 67 69 69 69 70

PART 3. CHEMISTRY 8. FISSION PRODUCT BEHAVIOR 8.1 Determination of Tritium and Hydrogen Concentrations in MSRE Pump Bowl Gas 8.1.1 Calibration Apparatus 8.1.2 Analysis for Hydrogen 8.1.3 Tritium Diffusion Studies 8.2 Examination of Deposits from the Mist Shield in the MSRE Fuel Pump Bowl 8.2.1 Tritium 8.3 Synthesis of Niobium Fluorides 8.4 Reaction Kinetics of Molybdenum and Niobium Fluoride in Molten Li2BeF4 Solutions 8.5 Mass Spectroscopy of Niobium Fluorides

73 73 74 75 76 76 82 85 85 86

9. COOLANT SALT CHEMISTRY AND TRITIUM CONTROL 9.1 Studies of Hydrogen Evolution and Tritium Exchange in Fluoroborate Coolant 9.2 Reaction of Sodium Fluoride-Sodium Tetrafluoroborate with Water 9.3 Identification of Corrosion Products in the Bubbler Tube of the Fluoroborate Test Loop 9.4 Mass Spectroscopy of Fluoroborate MSR Coolants 9.5 Spectroscopic Investigations of Hydrogen- and Deuterium-Containing Impurities in NaBF4 and NaF-NaBF4 Eutectics

88 88 90 92 93 94

9.6 Raman Spectra of the High-Temperature Phase of Polycrystalline NaBF4 9.7 A New Method for Synthesis of NaBF3OH 9.8 Solubility of BF3 Gas in Fluoride Melts 9.9 Equilibrium Phase Relationships in the System RbF-RbBF4 9.10 Activities in Alkali Fluoride-Fluoroborate Mixtures 9.11 High-Temperature Crystal Structure and Volume of Sodium Tetrafluoroborate and Related Compounds 9.12 Hydrogen Permeation through Oxide-Coated Metals

96 98 98 100 100 101 103

10. PHYSICAL CHEMISTRY OF MOLTEN SALTS 10.1 Thermodynamics of LiF-BeF2 Mixtures from EMF Measurements of Concentration Cells 10.2 Equilibrium Phase Relationships in the System LiF-BeF2-CeF3 10.3 Electrical Conductivity of Molten and Supercooled NaF-BeF2 (40-60'Mole %) 10.4 Glass Transition Temperatures in the NaF-BeF2 System 10.5 Raman Spectra of BeF42- in Molten LiF and NaF to 686°C 10.6 Bubble Formation by Impingement of a Jet Stream on a Fluid Surface 10.7 The Solubility of Hydrogen in Molten Salt 10.8 Enthalpy of UF4 from 298 to 1400K 10.9 Absorption Spectroscopy of Molten Fluorides: The Disproportionation Equilibrium of UF3 Solutions 10.10 The Oxide Chemistry of Pa4+ in the MSBR Fuel Solvent Salt 10.11 The Redox Potential of Protactinium in MSBR Fuel Solvent Salt 10.12 The Crystal Structures of Complex Fluorides 10.12.1 The Crystal Structure of CsU6F25 10.12.2 The Crystal Structure of α-KTh6F25 10.12.3 The Crystal Structure of Li2MoF6 10.12.4 The Crystal Structure of RbTh3F13 10.12.5 The Crystal Structure of Rb5Zr4F21 10.12.6 Discussion 10.13 Noncrystalline BeF2 at 25°C: Structure and Vibrational Motion 10.14 Relationshic between Entropy and Sonic Velocity in Molten Salts 10.15 A Reference Electrode System for Use in Fluoride Melts

107 107 109 109 110 112 115 115 117

11. CHEMISTRY OF MOLTEN-SALT REACTOR FUEL TECHNOLOGY 11.1 Extraction of Rubidium and Cesium from MSBR Fuel Solvent into Bismuth by Reduction with Lithium at 650°C 11.2 Distribution of Thorium between MSBR Fuel Solvent and Bismuth Saturated with Nickel and Thorium at 650°C 11.3 Bismuth-Manganese Alloys as Extractants for Rare Earths from MSBR Fuel Solvent 11.4 Removal of Solutes from Bismuth by Fractional Crystallization

129

12. DEVELOPMENT AND EVALUATION OF ANALYTICAL METHODS FOR MOLTEN-SALT REACTORS 12.1 Electroanalytical Studies of Titanium(IV) in Molten LiF-NaF-KF (46.5-11.5-42.0 Mole %) 12.2 Reference Electrode Studies in Molten NaBF4 12.3 Electrochemical-Spectral Studies of Molten Fluoride Salt Solutions 12.4 Spectral Studies of Molten Fluoride Salts 12.5 Analytical Studies of the NaBF4 Coolant Salt 12.6 In-Line Chemical Analysis

118 119 120 122 122 122 122 124 125 125 125 126 127

129 130 131 131 134 134 135 136 136 137 138

PART 4. MATERIALS DEVELOPMENT 13. EXAMINATION OF MSRE COMPONENTS 13.1 Examination of a Graphite Moderator Element 13.2 Auger Analysis of the Surface Layer on Graphite Removed from the Core of the MSRE 13.2.1 Auger Electron Spectroscopy

139 139 143 144

13.2.2 Results and Discussion 13.3 Examination of Hastelloy N Control Rod Thimble 13.4 Examination of the Sampler Assembly 13.5 Examination of a Copper Sample Capsule 13.6 Examination of the Primary Heat Exchanger 13.7 Examination of Freeze Valve 105

145 147 150 154 156 160

14. GRAPHITE STUDIES 14.1 Graphite Irradiations in HFIR 14.2 Graphite Fabrication 14.3 Graphite Development – Chemistry 14.4 Graphitization Study of a Lampblack-Pitch Carbon 14.5 Reduction of Graphite Permeability by Pyrolytic Carbon Sealing 14.6 Fundamental Studies of Radiation Damage Mechanisms in Graphite 14.7 Lattice Dynamics of Graphite

167 167 169 170 171 173 174 176

15. HASTELLOY N 15.1 Status of Laboratory Heat Postirradiation Evaluation 15.2 Postirradiation Creep Testing of Hastelloy N 15.3 The Unirradiated Mechanical Properties of Several Modified Commercial Alloys 15.4 The Weldability of Several Modified Commercial Alloys 15.5 Postirradiation Properties of Several Commercial Alloys 15.6 Status of Development of a Titanium-Modified Hastelloy N 15.7 Corrosion Studies 15.7.1 Fuel Salts 15.7.2 Fertile-Fissile Salt 15.7.3 Blanket Salt 15.7.4 Coolant Salt 15.7.5 Analysis of H2O Impurities in Fluoroborate Salts 15.8 Forced-Convection Loop Corrosion Studies 15.8.1 Operation of Forced-Convection Loop MSR-FCL-1 15.8.2 Metallurgical Analysis of MSR-FCL-1 15.8.3 Forced-Convection Loop MSR-FCL-2 15.9 Retention of Tritium by Sodium Fluoroborate 15.10 Support for Components Development Program 15.10.1 Metallurgical Examination of Inconel Bubbler Tube from PKP-1 Pump Loop 15.11 Corrosion of Hastelloy N in Steam

179 179 180 181 185 188 192 192 194 196 196 196 197 202 202 204 206 210 211 211 216

16. SUPPORT FOR CHEMICAL PROCESSING 16.1 Construction of a Molybdenum Reductive-Extractive Test Stand 16.2 Fabrication Development of Molybdenum Components 16.3 Welding Molybdenum 16.4 Development of Bismuth-Resistant Filler Metals for Brazing Molybdenum 16.5 Compatibility of Materials with Bismuth 16.6 Chemically Vapor Deposited Coatings 16.7 Molybdenum Deposition from MoF6

218 218 219 220 221 225 231 232

PART 5. MOLTEN-SALT PROCESSING AND PREPARATION 17. FLOWSHEET ANALYSIS 17.1 Protactinium Isolation Using Fluorination and Reductive Extraction 17.2 Combination of Discard Streams from the Protactinium Isolation System and the Metal Transfer System 17.3 Protactinium Isolation Using Oxide Precipitation 17.4 Stripping of Rare-Earth Fission Products from LiC1 in the Metal Transfer System 17.5 Importance of Uranium Inventory in an MSBR Processing Plant

235 235 237 237 240 240

18. PROCESSING CHEMISTRY 18.1 Measurement of Distribution Coefficients in Molten-Salt-Metal Systems 18.2 Solubilities of Thorium and Neodymium in Lithium-Bismuth Solutions 18.3 Oxide Precipitation Studies

242 242 244 245

19. ENGINEERING DEVELOPMENT OF PROCESSING OPERATIONS 19.1 Engineering Studies of the Metal Transfer Process for Rare-Earth Removal 19.2 Design of the Third Metal Transfer Experiment 19.3 Development of Mechanically Agitated Salt-Metal Contactors 19.4 Reductive Extraction Engineering Studies 19.5 Contactor Development: Pressure Drop, Holdup, and Flooding in Packed Columns 19.6 Development of a Frozen-Wall Fluorinator 19.7 Estimated Corrosion Rates in Continuous Fluorinators 19.8 Axial Dispersion in Simulated Continuous Fluorinators 19.9 Engineering Studies of Uranium Removal by Oxide Precipitation 19.10 Design of a Processing Materials Test Stand and the Molybdenum Reductive Extraction Equipment

249 249 254 255 256 260 262 264 265 267

20. CONTINUOUS SALT PURIFICATION SYSTEM

269

ORGANIZATIONAL CHART

271

267

ORNL-4728 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending August 31, 1971 Contents PART 1. MSBR DESIGN AND DEVELOPMENT 1. DESIGN 1.1 Molten-Salt Demonstration Reactor Design Study 1.1.1 General 1.1.2 Reactor Core 1.1.3 MSDR Off-Gas and Salt Pump-Back System 1.1.4 Drain Tank Cooling System 1.1.5 Drain Valve Cell 1.1.6 Drain Cell Catch Pan 1.2 Some Consequences of Tubing Failure in the MSBR Heat Exchanger 1.3 Side-Stream Processing of the MSBR Primary Flow for Xenon and/or Iodine Removal 1.4 MSBE Design 1.4.1 Reactor Core Power and Neutron Flux Distribution 1.4.2 Reactor Core Heat Removal 1.4.3 Maintenance Studies 1.5 MSBR Industrial Design Study

2 2 2 3 4 7 9 9 9 10 11 11 11 14 15

2. REACTOR PHYSICS 2.1 MSR Experimental Physics 2.1.1 HTLTR Lattice Experiments 2.2 Physics Analysis of MSBR 2.2.1 Neutron Irradiation Effects Outside the MSBR Core 2.2.2 MSBE Nuclear Characteristics 2.2.3 Fixed-Moderator Molten-Salt Reactor

16 16 16 18 18 20 21

3. SYSTEMS AND COMPONENTS DEVELOPMENT 3.1 Gaseous Fission Product Removal 3.1.1 Gas Separator and Bubble Generator 3.1.2 Bubble Formation and Coalescence Test 3.2 Gas System Test Facility 3.3 Off-Gas Systems 3.3.1 Off-Gas System for Molten-Salt Reactors 3.3.2 Computer Design of Charcoal Beds for MSR Off-Gas Systems 3.4 Molten-Salt Steam Generator 3.4.1 Steam Generator Industrial Program 3.4.2 Molten-Salt Steam Generator Technology Facility 3.4.3 Molten-Salt Steam Generator Test Proposals 3.5 Sodium Fluoroborate Test Loop 3.5.1 Inspection of PKP Pump Rotary Element 3.6 Coolant-Salt Technology Facility 3.7 MSBR Pumps 3.7.1 Salt Pumps for MSRP Technology Facilities 3.7.2 ALPHA Pump 3.7.3 Drain Tank Jet Pump System for MSDR

26 26 26 27 27 28 28 29 29 29 29 30 31 31 34 35 35 35 36

4. INSTRUMENTATION AND CONTROLS 4.1 Transient and Control Studies of the MSBR System Using a Hybrid Computer 4.2 MSRE Design and Operations Report, Part IIB, Nuclear and Process Instrumentation 4.3 Further Discussion of Instrumentation and Controls Development Needed for the Molten-Salt Breeder Reactor

38 38 38

5. HEAT AND MASS TRANSFER AND THERMOPHYSICAL PROPERTIES 5.1 Heat Transfer 5.2 Thermophysical Properties 5.3 Mass Transfer to Circulating Bubbles

39 39 41 41

38

PART 2. CHEMISTRY 6. POSTOPERATIONAL EXAMINATION OF MSRE 6.1 Examination of Moderator Graphite from MSRE 6.1.1 Results of Visual Examination 6.1.2 Segmenting of Graphite Stringer 6.1.3 Examination of Surface Samples by X-ray Diffraction 6.1.4 Examination with a Gamma Spectrometer 6.1.5 Milling of Surface Graphite Samples 6.1.6 Radiochemical and Chemical Analyses of MSRE Graphite 6.2 Cesium Isotope Migration in MSRE Graphite 6.3 Fission Product Concentrations on MSRE Surfaces 6.4 Metal Transfer in MSRE Salt Circuits

46 46 46 46 47 47 49 49 51 54 55

7. HYDROGEN AND TRITIUM BEHAVIOR IN MOLTEN SALT 7.1 The Solubility of Hydrogen in Molten 2LiF路BeF2 7.2 Permeation of Metals by Hydrogen 7.3 Tritium Control in an MSBR 7.3.1 Mass Spectrometric Examination of Stability of NaBF3OH 7.3.2 The Thermal Stability of Nitrate-Nitrite Mixtures 7.4 Dissociating-Gas Heat Transfer Scheme and Tritium Control in Molten-Salt Power Systems

56 56 57 59 59 59 60

8. PROCESSING CHEMISTRY 8.1 The Oxide Chemistry of Pa4+ in Molten LiF-BeF2-ThF4 8.2 The Oxide Chemistry of Pa5+ in Uranium-Containing Molten LiF-BeF2-ThF4 8.3 Reductive Extraction Distributions of Barium and. Thorium Between Bismuth-Lead Eutectic and Breeder Fuel Solvent 8.4 Removal of Cerium from Lithium Chloride by Zeolite

62 62 64

9. DEVELOPMENT AND EVALUATION OF ANALYTICAL METHODS FOR MOLTEN SALT REACTORS 9.1 In-Line Chemical Analysis of Molten Fluoride Salt Streams 9.2 Slotted Probe for In-Line Spectral Measurements 9.3 In-Line Determination of Hydrolysis Products in NaBF4 Cover Gas 9.4 Determination of Hydrogen in Fluoroborate Salts 9.5 Voltammetric and Electrolysis Studies of Hydroxide Ion in Molten NaBF4 9.6 Electroanalytical Studies in the NaBF4 Coolant Salt 9.7 Electroanalytical Studies of Ni(II) in Molten Fluoride Fuel Solvent 10. OTHER FLUORIDE RESEARCHES 10.1 Absorption Spectroscopy of Molten Fluorides 10.1.1 The Disproportionation Equilibrium of UF3 Solutions 10.1.2 Estimation of the Available F- Concentrations in Melts by Measurement of UF4 Coordination Equilibria

67 67 69 69 70 71 73 74 75 75 77 77 77 77

10.2 Solubility of BF3 in Fluoride Melts 10.3 Fluorides and Oxyfluorides of Molybdenum and Niobium 10.3.1 Mass Spectroscopy of Molybdenum Fluorides 10.3.2 Mass Spectroscopy of Niobium Fluorides and Oxyfluorides 10.4 Electrical Conductivity of Molten and Supercooled Mixtures of NaF-BeF2 10.5 Glass Transition Temperatures in the NaF-BeF2 System 10.6 Enthalpy of Lithium Fluoroborate from 298-700K: Enthalpy and Entropy of Fusion 10.7 Nonideality of Mixing in Li2BeF4LiI 11. EXAMINATION OF MSRE COMPONENTS 11.1 Examination of Hastelloy N Components Exposed to Fuel Salt in the MSRE 11.2 Examination of Components from In-Pile Loop 2 11.3 Observations of Grain Boundary Cracking in the MSRE 11.4 Examination of a Graphite Moderator Element 11.5 Auger Analysis of the Surface Layer on Graphite Removed from the Core of the MSRE

78 80 80 80 81 82 85 86 89 89 94 96 106 107

PART 3. MATERIALS DEVELOPMENT 12. GRAPHITE STUDIES 12.1 The Irradiation Behavior of Graphite at 715째C 12.2 Procurement of Various Grades of Carbon and Graphite 12.3 X-Ray Studies 12.4 Thermal Property Testing 12.5 Helium Permeability Measurements on Various Grades of Graphite 12.6 Reduction of Graphite Permeability by Pyrolytic Carbon Sealing 12.7 The Magnified Topography of Graphite Sealed with Pyrolytic Carbon 12.8 Reduction of Permeability by Fluid Impregnation 12.9 Fundamental Studies of Radiation Damage Mechanisms in Graphite

111 112 114 116 117 118 119 120 121 122

13. HASTELLOY N 13.1 Electron Microscopy Studies 13.1.1 Microstructures of Hf-Modified Hastelloy N Laboratory Melts 13.1.2 Ni3Ti Precipitation in Ti-Modified Hastelloy N 13.1.3 Strain-Induced Precipitation in Modified Hastelloy N 13.2 Mechanical Properties of Unirradiated Modified Hastelloy N 13.3 Weldability of Several Modified Commercial Alloys 13.4 Creep-Rupture Properties of Hastelloy N Modified with Niobium, Hafnium, and Titanium 13.5 Corrosion Studies 13.5.1 Fuel Salts 13.5.2 Fertile-Fissile Salt 13.5.3 Blanket Salt 13.5.4 Coolant Salt 13.6 Analysis of High-Level Probe from Sump Tank of PKP-1 13.7 Forced-Convection Loop Corrosion Studies 13.7.1 Operation of Forced-Convection Loop MSR-FCL-1A 13.7.2 Metallurgical Analysis of Forced-Convection Loop MSR-FCL-1A 13.7.3 Operation of Forced-Convection Loop MSR-FCL-2 13.7.4 Metallurgical Analysis of Forced-Convection Loop MSR-FCL-2 13.8 Corrosion of Hastelloy N in Steam 13.9 Evaluation of Duplex Tubing for Use in Steam Generators

125 125 125 129 130 132 132 137 138 139 145 145 145 150 150 150 151 151 153 153 156

14. SUPPORT FOR CHEMICAL PROCESSING 14.1 Construction of a Molybdenum Reductive-Extraction Test Stand 14.2 Fabrication Development of Molybdenum Components 14.3 Welding Molybdenum 14.4 Development of Brazing Techniques for Fabricating the Molybdenum Test Loop

163 163 166 169 172

14.4.1 Resistance Furnace Brazing 14.4.2 Induction Vacuum Brazing 14.4.3 Induction Field Brazing 14.5 Compatibility of Materials with Bismuth 14.6 Chemical Vapor Deposited Coatings 14.7 Molybdenum Deposition from MoF6

172 172 173 173 176 177

PART 4. MOLTEN-SALT PROCESSING AND PREPARATION 15. FLOWSHEET ANALYSIS 15.1 Cost Estimate for an MSBR Processing Plant 15.2 Comparison of Costs for Alternate Off-Gas Treatment Methods for an MSBR Processing Plant 15.3 Effect of Noble-Metal and Halogen Removal Times on the Heat Generation Rate in an MSBR Processing Plant 15.4 Long-Term Disposal of MSBR Wastes 15.5 Availability of Natural Resources Required for Molten Salt Breeder Reactors

179 179

16. PROCESSING CHEMISTRY 16.1 Distribution of Lithium and Bismuth Between Liquid Lithium-Thorium-Bismuth Alloys and Molten LiCl 16.2 Mutual Solubilities of Thorium and Rare Earths in Liquid Bismuth 16.3 Oxide Precipitation Studies 16.4 Chemistry of Fuel Reconstitution

191

17. ENGINEERING DEVELOPMENT OF PROCESSING OPERATIONS 17.1 Lithium Transfer During Metal Transfer Experiment MTE-2 17.2 Operation of Metal Transfer Experiment MTE-2B 17.3 Development of Mechanically Agitated Salt-Metal Contactors 17.4 Design of the Third Metal Transfer Experiment 17.5 Reductive Extraction Engineering Studies 17.6 Development of a Frozen-Wall Fluorinator: Induction Heating Experiments 17.7 Predicted Performance of Continuous Fluorinators 17.8 Engineering Studies of Uranium Oxide Precipitation 17.9 Design of a Processing Materials Test Stand and the Molybdenum Reductive Extraction Equipment 17.10 Development of a Bismuth-Salt Interface Detector

202 202 204 207 209 212 214 217 220

18. CONTINUOUS SALT PURIFICATION

226

183 186 186 189

191 193 196 199

222 222

ORNL-4782 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending February 29, 1972 PART 1. MSBR DESIGN AND DEVELOPMENT 1. DESIGN 1.1 Molten-Salt Demonstration Reactor Design Study 1.1.1 General 1.1.2 Reactor Core 1.1.3 Graphite Temperatures 1.1.4 Cell Cooling 1.2 Side-Stream Processing of MSBR Primary Flow for Iodine Removal 1.3 MSBR Industrial Design Study 1.4 MSBE Design 1.5 Bubble Behavior in the MSBR Primary Salt System

2 2 2 2 6 8 8 9 12 13

2. REACTOR PHYSICS 2.1 Experimental Physics 2.1.1 HTLTR Lattice Experiments 2.2 Physics Analysis of MSBR 2.2.1 Radiation Heating in MSR Pumps 2.2.2 MSBE Control-Rod Worths 2.2.3 Molten-Salt Converter Reactors Using Plutonium

18 18 18 21 21 22 23

3. SYSTEMS AND COMPONENTS DEVELOPMENT 3.1 Gaseous Fission Product Removal 3.1.1 Bubble Separator and Bubble Generator 3.1.2 Bubble Formation and Coalescence Test 3.1.3 Bubble Separator Analyses 3.2 Gas System Technology Facility 3.3 Molten-Salt Steam Generator Industrial Program 3.4 Coolant-Salt Technology Facility 3.5 Salt Pumps 3.5.1 Salt Pumps for MSRP Technology Facilities 3.5.2 ALPHA Pump 3.5.3 Molten-Salt Mixer, Laboratory Scale

28 28 28 29 29 32 33 33 34 34 35 37

4. INSTRUMENTATION AND CONTROLS 4.1 Transient and Control Studies of the MSBR System Using a Hybrid Computer

38 38

5. HEAT AND MASS TRANSFER AND PHYSICAL PROPERTIES 5.1 Heat Transfer 5.2 Wetting Studies 5.3 Mass Transfer to Circulating Bubbles

39 39 40 41

PART 2. CHEMISTRY 6. FISSION PRODUCT BEHAVIOR 6.1 Some Factors Affecting the Deposition Intensity of Noble-Metal Fission Products 6.2 Effects of Selected Fission Products on Hastelloy N, Nickel,

45 45

and Type 304L Stainless Steel at 650째C 6.3 Reaction of CoF3 with Tellurium

50 51

7. BEHAVIOR OF HYDROGEN AND ITS ISOTOPES 7.1 Solubility of Hydrogen in Molten Salt 7.2 Initial Tritium Chemistry in the Core of a Molten-Salt Reactor 7.3 Permeation of Hydrogen Through Metals at Low Pressures 7.4 Influence of Films or Coatings on Hydrogen Permeation Rates 7.5 Experiments on Hydrogen Evolution from Fluoroborate Coolant Salt 7.6 Apparatus for Infrared Spectral Studies of Molten Salts 7.7 Infrared Spectral Studies of the Chemical Behavior of BF3OH- and BF3OD- Ions in Molten NaF-NaBF4 7.8 Thermal Stability of NaNO3, KNO3, NaNO2, and HITEC

53 53 53 54 56 57 59

8. FLUOROBORATE CHEMISTRY 8.1 Solubility of BF3 in Fluoride Melts 8.1.1 Reactor Applications 8.2 Free Energies of Formation of NaFeF3 and NaNiF3; Their Relationship to the Corrosion of Hastelloy N by Fluoroborates 8.3 Preparation of Fused Sodium Fluoroborate for the Coolant Salt Technology Facility

63 63 63

9. PROTACTINIUM CHEMISTRY 9.1 Oxide Chemistry of Protactinium in MSBR Fuel Salt 9.2 Binary Solid Solutions of PaO2 and Other Actinide Dioxides and Their Exchange Equilibria with Molten-Salt Reactor Fluorides 9.3. Ternary Solid Solutions of ThO2, PaO2, and UO2

70 70

10. DEVELOPMENT AND EVALUATION OF ANALYTICAL METHODS FOR MOLTEN-SALT REACTORS 10.1 In-Line Chemical Analysis of Molten Fluoride Salt Streams 10.2 Theoretical Considerations of the Voltammetric In-Line Determination of Uranium(III) 10.3 Electroanalytical Studies of Titanium(IV) in Molten LiF-BeF2-ZrF4 (65.4-29.6-5.0 Mole %) 10.4 Electrochemical Studies of Bismuth(III) in Molten LiF-BeF2-ZrF4 at 500째C 10.5 Voltammetry of Chromium(III) in Molten NaBF4-NaF (92-8 Mole %) 10.6 Voltammetric and Hydrolysis Studies of Protonated Species in Molten NaBF4 10.7 Determination of Hydrogen in NaF-NaBF4 Salts 10.8 Spectral Studies of Molten Salts 11. OTHER MOLTEN-SALT RESEARCHES 11.1 The Oxide Chemistry of Niobium in Molten LiF-BeF2 Mixtures 11.1.1 Equilibrations of Nb2O5 and BeO with Molten LiF-BeF2 Mixtures 11.1.2 Equilibrations Involving Nickel Niobates in Molten Li2BeF4 11.2 The Reaction of MoF6 with Niobium 11.3 Thermodynamics of LiF-BeF2 Mixtures 11.4 Electrochemical Mass Transport in Molten Beryllium Fluoride-Alkali Fluoride Mixtures 11.5 Electrical Conductance in Beryllium Fluoride Rich NaF-BeF2 Mixtures 11.6 The Disproportionation Equilibrium of UF3 Solutions 11.7 The Raman Spectra of Be2F73- and Higher Polymers of Beryllium Fluorides in the Crystalline and Molten State 11.8 Raman Spectra of Molten and Crystalline Potassium Dichromate 11.9 Nonideality of Mixing in the Systems Li2BeF4-LiI, Na2BeF4-NaI, and Cs2BeF4-CsI

59 62

65 68

72 74 77 77 80 81 82 82 83 83 84 87 87 87 89 91 95 96 98 98 100 103 106

PART 3. MATERIALS DEVELOPMENT 12. INTERGRANULAR CRACKING OF STRUCTURAL MATERIALS EXPOSED TO FUEL SALT 12.1 Examination of Hastelloy N Components from the MSRE 12.1.1 Freeze Valve 105 12.1.2 Control Rod Thimble 12.1.3 Sampler Cage Rod 12.1.4 Mist Shield 12.2 Auger Analysis of the Surface Layers on Graphite from the Core of the MSRE 12.3 Auger Analysis of the Surface of a Fractured Hastelloy N Sample 12.4 Intergranular Corrosion of Hastelloy N 12.5 Tube-Burst Experiments 12.6 Cracking of Samples Electroplated with Tellurium 12.7 Cracking of Hastelloy N Being Creep Tested in Tellurium Vapor 12.8 Intergranular Cracking of Materials Exposed to Sulfur and Several Fission Product Elements 12.9 Mechanical Properties of Hastelloy N Modified with Several Elements 12.10 Status of Intergranular Cracking Studies

109 109 109 111 115 116 117 122 123 126 128 128 134 136 141

13. GRAPHITE STUDIES Introduction 13.1 Graphite Development 13.2 Procurement of Various Grades of Carbon and Graphite 13.3 Texture Determinations 13.4 Thermal Property Testing 13.5 Nominal Helium Permeability Parameters for Various Grades of Graphite 13.6 Reduction of Helium Permeability of Graphite by Pyrolitic Carbon Sealing 13.7 Characterization of Pyrocarbon Sealants for Graphite Using Reflected Light and Scanning Electron Microscopes

144 144 144 149 149 150 151 151

14. HASTELLOY N 14.1 Development of a Titanium-Modified Hastelloy N 14.2 Alloys with Exceptional Strength 14.3 Weldability of Commercial Alloys of Modified Hastelloy N 14.4 Electron Microscope Studies 14.4.1 Intermetallic Precipitation in Hastelloy N 14.4.2 Precipitation in New Commercial Alloys 14.4.3 Modification of X-Ray Diffraction Techniques 14.5 Salt Corrosion Studies 14.5.1 Fuel Salt 14.5.2 Fertile-Fissile Salt 14.5.3 Blanket Salt 14.5.4 Coolant Salt 14.6 Forced-Convection Loop Corrosion Studies 14.6.1 Operation of Loop MSR-FCL-1A 14.6.2 Results from Loop MSR-FCL-1A 14.6.3 Operation of Loop MSR-FCL-2 14.6.4 Results from Loop MSR-FCL-2 14.7 Corrosion of Hastelloy N in Steam 14.8 Evaluation of Duplex Tubing for Use in Steam Generators

161 161 163 166 171 172 173 173 174 174 177 177 177 179 179 179 180 180 182 189

15. SUPPORT FOR CHEMICAL PROCESSING 15.1 Construction of a Molybdenum Reductive-Extraction Test Stand 15.2 Fabrication Development of Molybdenum Components 15.3 Welding of Molybdenum 15.4 Development of Brazing Techniques for Fabricating the Molybdenum Test Loop 15.5 Compatibility of Materials with Bismuth

192 192 194 195 195 197

155

15.5.1 Tantalum and T-111 15.5.2 Graphite 15.5.3 Tungsten-Coated Hastelloy N 15.5.4 Molybdenum 15.6 Molybdenum Braze Alloy Compatibility

197 198 199 199 202

PART 4. MOLTEN-SALT PROCESSING AND PREPARATION 16. FLOWSHEET ANALYSIS 16.1 Design Study and Cost Estimates of a Processing Plant for a 1000-MWe MSBR 16.2 Multiregion Code for MSBR Processing Plant Flowsheet Calculations

204 204 205

17. PROCESSING CHEMISTRY 17.1 Distribution of Lithium and Bismuth between Liquid Lithium-Bismuth Alloys and Molten LiCl 17.2 Solubility of Europium in Liquid Bismuth 17.3 Integral Heats of Lithium-Bismuth Solutions 17.4 Protactinium Oxide Precipitation Studies 17.5 Chemistry of Fuel Reconstitution

207

18. ENGINEERING DEVELOPMENT OF PROCESSING OPERATIONS 18.1 Lithium Transfer during Metal Transfer Experiment MTE-2 18.2 Operation of Metal Transfer Experiment MTE-2B 18.3 Installation, Testing, and Charging of Materials to the Third Metal Transfer Experiment 18.4 Design of the Metal Transfer Process Facility 18.5 Development of Mechanically Agitated Salt-Metal Contactors 18.6 Reductive Extraction Engineering Studies 18.7 Design of the Reductive-Extraction Process Facility 18.8 Frozen-Wall Fluorinator Development 18.9 Engineering Studies of Uranium Oxide Precipitation 18.10 Design of a Processing Materials Test Stand and the Molybdenum Reductive Extraction Equipment 18.11 Development of a Bismuth-Salt Interface Detector

216 216 217 221 224 225 227 230 230 234

19. CONTINUOUS SALT PURIFICATION

241

207 209 209 210 212

238 239

ORNL-4832 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending August 31, 1972 Introduction

vii

Summary

ix PART 1. MSBR DESIGN AND DEVELOPMENT

1. DESIGN 1.1 Lead-Cooled MSBRs 1.2 MSBR Industrial Design Study 1.2.1 Drain Tank 1.2.2 Physics Calculations 1.2.3 Chemical Processing 1.3 Xenon Behavior in the MSBR Fuel Salt System 1.4 Hybrid Computer Simulation of the MSBR

2 2 5 5 10 11 11 13

2. REACTOR PHYSICS 2.1 Analysis of HTLTR-MSR Lattice Experiments 2.2 Nuclear Performance of Lead-Cooled Molten-Salt Reactors 2.3 Plutonium Use in Molten-Salt Reactors 2.3.1 Fuel for Molten-Salt Converter Reactors 2.3.2 Start-up of an MSBR on Plutonium Fuel 2.3.3 ROD Code Modifications

14 14 14 16 16 22 25

3. SYSTEMS AND COMPONENTS DEVELOPMENT 3.1 Gaseous Fission Product Removal 3.1.1 Bubble Separator and Bubble Generator 3.1.2 Bubble Formation and Coalescence Test 3.1.3 Mass Transfer to Circulating Bubbles 3.2 Gas Systems Technology Facility 3.3 Molten-Salt Steam Generator Industrial Program 3.4 Coolant-Salt Technology Facility (CSTF) 3.5 Salt Pumps 3.5.1 Salt Pumps for MSRP Technology Facilities 3.5.2 ALPHA Pump

26 26 26 29 29 30 30 31 32 32 33

4. HEAT TRANSFER AND PHYSICAL PROPERTIES 4.1 Heat Transfer 4.2 Thermal Conductivity

35 35 36

PART 2. CHEMISTRY 5. BEHAVIOR OF HYDROGEN AND ITS ISOTOPES 5.1 The Solubility of Hydrogen in Molten Salt 5.2 Hydrogen Permeation Through Metals 5.3 The Chemisorption of Tritium on Graphite

38 38 39 42

6. FLUOROBORATE CHEMISTRY 6.1 Solubility of BF3 in Molten LiF-BeF2-ThF4 6.2 Solubility of BF3 in MSBR Primary Salt Containing 8 Mole % NaF: Some Safety Considerations 6.3 Corrosion of Hastelloy N by Fluoroborate Melts

43 43

7. BEHAVIOR OF SIMULATED FISSION PRODUCTS 7.1 Effects of Selected Fission Products on Metals 7.2 Stability and Volatility of Metal Tellurides

47 47 48

8. DEVELOPMENT AND EVALUATION OF ANALYTICAL METHODS 8.1 In-Line Chemical Analysis of Molten Fluoride Salt Streams 8.2 Voltammetric Studies of Protonated Species in Molten NaBF4-NaF (92-8 mole %) 8.3 Infrared Spectral Studies of NaBF4-NaF 8.4 Studies of Protons in Molten NaBF4 8.5 Analysis of Coolant Cover Gas 8.6 Spectral Studies of Molten Salts

50 50 50 52 52 53 54

9. OTHER MOLTEN-SALT RESEARCH 9.1 The Disproportionation Equilibrium of UF3 Solutions in Graphite 9.2 EMF Studies of Oxide Equilibria in Molten Fluorides 9.3 The Lithium Fluoride-Tetrafluoroborate Phase Diagram 9.4 Chronopotentiometry Based on Diffusion of Mobile Nonelectroactive Species

56 56 57 58 59

43 44

PART 3. MATERIALS DEVELOPMENT 10. INTERGRANULAR CRACKING OF STRUCTURAL MATERIALS EXPOSED TO FUEL SALT 10.1 Cracking of Samples Electroplated with Tellurium 10.2 Intergranular Cracking of Several Alloys When Exposed to Tellurium Vapor 10.3 Mechanical Properties of Structural Materials Containing Strontium and Tellurium 10.4 The Isothermal Diffusion of 127Te Tracer in Hastelloy N, Ni-200 and Type 304L Stainless Steel Specimens 10.5 Tube-Burst Experiments 10.6 Strain Cycle Experiments 10.7 Identification of Reaction Products from Tellurium-Structural-Material Interactions 10.7.1 Knudsen Cell Reactions 10.7.2 Possible Tellurides in Hastelloy N 10.7.3 Tellurides from Knudsen Cell Reactions 10.7.4 Tellurides from Other Reaction Methods 10.7.5 Summary 10.8 Auger Electron Spectroscopy of Intergranular Fracture Surfaces of Nickel and Hastelloy N Exposed to Tellurium Vapor at 700째C 10.8.1 Method 10.8.2 Nickel 10.8.3 Hastelloy N 10.9 Design of an In-Reactor Experiment to Study Fission Product Effects on Metals 10.9.1 Design Criteria 10.9.2 Configuration 10.9.3 Thermal Considerations 10.9.4 Containment 10.9.5 Fuel Salt Chemistry

63 63 63 69

11. GRAPHITE STUDIES 11.1 The Irradiation Behavior of Graphite 11.2 Procurement and Characterization of Various Grades of Graphite 11.3 Characterization of ORNL Graphites

95 95 100 101

70 71 76 79 81 82 83 83 85 86 87 88 88 90 90 91 91 93 93

11.4 Graphite Fabrication 11.5 Thermal Property Testing 11.6 Reduction of Helium Permeability of Graphite by Pyrolytic Carbon Sealing 11.7 Irradiation of Pyrocarbons 11.8 Examination of Unirradiated and Irradiated Pyrocarbon Strips with the Scanning Electron Microscope (SEM) 11.9 Texture Determinations

103 106 107 111 111 113

12. HASTELLOY N 12.1 Mechanical Properties of Several Commercial Heats of Modified Hastelloy N 12.2 Irradiation of Hastelloy N in the HFIR 12.3 Salt Corrosion Studies 12.3.1 Fuel Salt 12.3.2 Fertile-Fissile Salt 12.3.3 Blanket Salt 12.3.4 Coolant Salt 12.3.5 Corrosion of Type 304L Stainless Steel and Hastelloy N

by Mixtures of Boron Trifluoride, Air, and Argon 12.3.6 Oxide Additions to Sodium Fluoroborate 12.4 Forced-Convection Loop Corrosion Studies 12.4.1 Operation of Forced-Convection Loop MSR-FCL-1A 12.4.2 Corrosion Results from Forced-Convection Loop MSR-FCL-1A 12.4.3 Operation of Forced-Convection Loop MSR-FCL-2 12.4.4 Corrosion Results from Forced-Convection Loop MSR-FCL-2 12.5 Corrosion of Hastelloy N in Steam

117 117 120 124 126 126 127 127

13. SUPPORT FOR CHEMICAL PROCESSING 13.1 Construction of a Molybdenum Reductive-Extraction Test Stand 13.2 Welding of Molybdenum 13.3 Development of Brazing Techniques for Fabricating the Molybdenum Test Loop 13.4 Compatibility of Materials with Bismuth and Bismuth-Lithium Solutions 13.4.1 Tantalum Alloys 13.4.2 Molybdenum Alloys 13.4.3 Graphite

147 147 147 149 151 152 152 152

132 134 135 135 135 136 137 137

PART 4. FUEL PROCESSING FOR MOLTEN-SALT REACTORS 14. FLOWSHEET ANALYSIS 14.1 Multiregion Code for MSBR Processing Plant Calculations

159 159

15. PROCESSING CHEMISTRY 15.1 Equilibria in Fused Salt-Liquid Alloy Systems 15.2 Solubility of Thorium in Liquid Li-Pb Alloys 15.3 Reductive Extraction of Titanium and Cesium 15.4 Chemistry of Fuel Reconstitution 15.5 Protactinium Oxide Precipitation Studies

160 160 162 163 164 165

16. ENGINEERING DEVELOPMENT OF PROCESSING OPERATIONS 16.1 Operation of Metal Transfer Experiment MTE-3 16.2 Design of the Metal Transfer Process Facility 16.3 Development of Mechanically Agitated Salt-Metal Contactors 16.4 Reductive-Extraction Engineering Studies 16.5 Reductive-Extraction Processing Facility Development 16.6 Design of a Processing Materials Test Stand and the Molybdenum Reductive-Extraction Equipment 16.7 Removal of Bismuth from MSBR Fuel Salt

168 168 171 171 173 175 177 178

16.8 Frozen-Wall Fluorinator Development 16.9 Uranium Oxide Precipitation Studies 16.10 Development of a Bismuth-Salt Interface Detector 17. CONTINUOUS SALT PURIFICATION

180 182 183 185

ORNL-5011 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending August 31, 1974 INTRODUCTION

vii

SUMMARY

ix PART 1. MSBR DESIGN, DEVELOPMENT, AND SAFETY

1. DESIGN AND SYSTEMS ANALYSIS 1.1 ORNL Study of MSR Designs 1.1.1 Plant and Equipment Studies 1.1.2 Neutronic Analysis 1.1.3 Xenon Behavior 1.2 Tritium Behavior in Molten-Salt Systems 1.2.1 Reactor Calculations 1.2.2 Studies of Loop Experiments 1.3 Molten-Salt Reactor Information System

2 2 2 2 3 3 3 4 5

2. SYSTEMS AND COMPONENTS DEVELOPMENT 2.1 Gaseous Fission Product Removal 2.1.1 Bubble Generator 2.1.2 Bubble Separator 2.1.3 Bubble Formation and Coalescence Test 2.1.4 Bubble Size Measurement 2.1.5 Mass Transfer to Circulating Bubbles 2.1.6 Bubble Generation Analysis 2.2 Molten-Salt Steam Generator Industrial Program 2.2.1 Resumption of the Conceptual Design Study 2.2.2 Preliminary Results 2.3 Gas Systems Technology Facility 2.4 Coolant-Salt Technology Facility 2.5 Forced Convection Loop (MSR-FCL-2 and 2b) 2.5.1 Introduction 2.5.2 Operation of MSR-FCL-2 with Fluoroborate 2.5.3 Post Run Inspections 2.5.4 Cleanup and Modifications 2.5.5 Purging the System and Adding Salt 2.5.6 Operation of MSR-FCL-2b with Fuel Salt

6 6 6 6 6 7 7 8 9 9 9 10 10 14 14 14 14 15 15 16

3. REACTOR SAFETY 3.1 Safety Events in MSBR 3.2 MSBR Neutronic Excursions

18 18 18 PART 2. CHEMISTRY

4. FUEL SALT CHEMISTRY 4.1 The Chemistry of Tellurium in Molten Li2BeF4 4.2 Exposure of Metallurgical Samples to Tellurium Vapor 4.3 Removal of Iodide from LiF-BeF2 Melts by HF-H2 Sparging:

22 22 22

Application to Iodine Removal from MSBR Fuel 4.4 Protactinium Oxide Precipitation Studies 4.5 Solubility of BF3 in Salts of Molten-Salt Reactor Interest

23 24 24

5. COOLANT SALT CHEMISTRY 5.1 Oxide and Hydroxide Chemistry of Fluoroborate Melts 5.2 Corrosion of Structural Alloys by Fluoroborate Melts 5.3 Evaluation of Fluoroborate and Alternate Coolants 5.4 Density and Viscosity of Several Molten Fluoride Mixtures

25 25 25 26 28

6. TRITIUM BEHAVIOR 6.1 Permeation of Hydrogen Isotopes Through Structural Metals 6.2 The Solubilities of Hydrogen, Deuterium, and Helium in Molten Li2BeF4 6.3 Chemisorption of Tritium on Graphite

30 30 30 30

7. OTHER RESEARCH 7.1 The Wetting of Graphite by Bismuth and Bismuth-Lithium Alloys as Determined by the Sessile Drop Method

34

8. DEVELOPMENT AND EVALUATION OF ANALYTICAL METHODS 8.1 In-Line Analysis of Breeder Fuel 8.2 Determination of Trivalent Uranium in Simulated MSRE Fuel 8.3 In-Line and Other Support Analyses for Circulating NaF-NaBF4 Coolant 8.4 Studies on the Electroreduction of Uranium(IV) in Molten LiF-BeF2-ZrF4 8.5 Electroanalytical Studies of Tellurium in Molten LiF-BeF2 -ZrF4 (65.6-29.4-5.0 mole %) 8.6 Electroanalytical Studies of Bismuth in Molten LiF-BeF2-ZrF4 (65.6-29.4-5.0-mole %) 8.7 Electroanalytical Studies in Molten NaBF4 8.8 Spectrophotometric Research 8.9 Spectral Studies of f-d and f-f Transitions of Pa(IV) in Molten LiF-BeF2-ThF4 8.10 Spectrophotometric Developments for Improved Analytical Methods for Fluoroborate Coolant Systems

35 35 36 37 42

9. INORGANIC AND PHYSICAL CHEMISTRY 9.1 The Equilibrium of Dilute UF3 Solutions Contained in Graphite 9.2 Effects of Oxygen on the UF3 /UF4 Equilibrium 9.3 Porous Electrode Studies 9.4 Formation Free Energies and Activity Coefficients in Fuel Salt Mixtures 9.5 The Chemistry and Thermodynamics of Molten-Salt Reactor Fuels 9.6 Oxide Chemistry of Niobium(V) in Molten LiF-BeF2 Mixtures

47 47 48 49 51 51 53

34

43 43 44 45 45 46

PART 3. MATERIALS DEVELOPMENT 10. DEVELOPMENT OF MODIFIED HASTELLOY N 10.1 Procurement of New Test Materials 10.2 Weldability of Commercial Alloys of Modified Hastelloy N 10.3 Mechanical Properties of Modified Hastelloy N 10.4 Transmission Electron Microscopy of Ti-Modified Hastelloy N Alloys 10.5 Salt Corrosion Studies 10.5.1 Fuel Salt Thermal Convection Loop Results 10.5.2 Coolant Salt Thermal Convection Loop Results 10.5.3 Blanket Salt Thermal Convection Loop Results 10.5.4 Status of Thermal Convection Loop Program with Fuel and Coolant Salts 10.5.5 Forced Circulation Loop Results 10.5.6 Surveillance Specimens from the Coolant-Salt Technology Facility

57 57 57 61 62 69 69 74 75 75 75 77

10.6 Corrosion of Hastelloy N and Other Alloys in Steam 10.7 Intergranular Cracking of Alloys Exposed to Tellurium 10.8 Chemistry of Salt-Metal-Tellurium System 10.9 Auger Observations Relative to Intergranular Cracking 10.9.1 Fracture Surface Analysis 10.9.2 High Temperature Surface Studies 10.10 In-Reactor Fueled Experiments 10.10.1 Design 10.10.2 Calculated Operation and Test Conditions 10.10.3 Preliminary Operating Data

77 79 79 80 81 81 81 82 82 84

11. FUEL PROCESSING MATERIALS DEVELOPMENT 11.1 Static Capsule Tests of Graphite with Bismuth and Bismuth-Lithium Solutions 11.2 Thermal Convection Loop Tests of Molybdenum, Tantalum, and Graphite in Bismuth-Lithium Solution

86 86

12. GRAPHITE STUDIES 12.1 Property Changes in Near-Isotropic Grades of Graphite Irradiated at 715째C to Fluences as High as 4.2x1022 neutrons/cm2 12.1.1 Materials 12.1.2 Testing 12.1.3 Property Changes as Functions of Fluence 12.1.4 Conclusions

92

89

92 92 94 95 95

PART 4. FUEL PROCESSING FOR MOLTEN-SALT REACTORS 13. PROCESSING CHEMISTRY 13.1 Chemistry of Fluorination and Fuel Reconstitution 13.2 Equilibria in Fused Salt-Liquid Alloy Systems

100 100 101

14. ENGINEERING DEVELOPMENT OF PROCESSING OPERATIONS 14.1 Examination of Equipment from Metal Transfer Experiment MTE-3 14.2 Installation of Metal Transfer Experiment MTE-3B 14.3 Design of the Metal Transfer Process Facility 14.4 Salt-Metal Contactor Development: Experiments with a Mechanically Agitated Nondispersing Contactor in the Salt-Bismuth Flow-through Facility 14.5 Salt-Metal Contactor Development: Experiments with a Mechanically Agitated Nondispersing Contactor Using Water and Mercury 14.5.1 Theory 14.5.2 Experimental Apparatus 14.5.3 Results and Conclusions 14.6 Continuous Fluorinator Development: Autoresistance Heating Test AHT-3 14.6.1 Experimental Equipment and Procedure 14.6.2 Experimental Results 14.6.3 Distribution of Current Densities in the Autoresistance Heating Equipment 14.7 Fuel Reconstitution Development: Design of a Fuel Reconstitution Engineering Experiment 14.8 Performance of Open Bubble Columns 14.8.1 Axial Dispersion in Open Bubble Columns 14.8.2 Mass Transfer Rates in Open Bubble Columns 14.9 Conceptual Design of an MSBR Processing Engineering Laboratory

102 102 112 114 114 119 119 121 121 122 122 124 124 127 129 130 130 132

PART5. SALT PRODUCTION 15. PRODUCTION OF FLUORIDE-SALT MIXTURES FOR RESEARCH AND DEVELOPMENT PROGRAM

134

ORNL-5047 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending February 28, 1975 Introduction

vii

SUMMARY

ix PART 1. MSBR DESIGN, DEVELOPMENT, AND SAFETY

1. DESIGN AND SYSTEMS ANALYSIS 1.1 Tritium Behavior in Molten-Salt Systems 1.1.1 MSBR Tritium Studies 1.1.2 Coolant Salt Technology Facility Calculations 1.2 Neutronic Analyses 1.3 High-Temperature Design 1.3.1 Analytical Investigation of the Applicability of Simplified Ratchetting and Creep-Fatigue Rules to Reactor System Component Geometries 1.3.2 Inelastic Analyses of MSR Piping Subjected to Internal Pressure and Transient Temperature Cycles

3 3 3 11 14 15

2. SYSTEMS AND COMPONENTS DEVELOPMENT 2.1 Molten-Salt Steam Generator Industrial Program 2.2 Gas-Systems Technology Facility 2.2.1 General 2.2.2 Mark II Pump 2.2.3 Densitometer 2.3 Coolant-Salt Technology Facility 2.4 Forced-Convection Loops 2.4.1 Operation of MSR-FCL-2b 2.4.2 MSR FCL-3 and FCL4

23 23 23 23 24 25 25 29 29 31

3. SAFETY STUDIES 3.1 Salt-Spill Accidents 3.1.1 Potential Causes 3.1.2 Direct Consequences 3.1.3 Deferred Consequences

32 32 32 34 35

15 21

PART 2. CHEMISTRY 4. FUEL-SALT CHEMISTRY 4.1 Tellurium Deposition on Hastelloy N Surfaces in an MSBR 4.2 Exposure of Metallurgical Samples to Tellurium Vapor 4.3 Effect of Oxygen on the UF3/UF4 Equilibrium in Molten Fluoride Solutions 4.4 The Uranium Tetrafuoride-Hydrogen Equilibrium in Molten Fluoride Solutions 4.5 Porous-Electrode Studies

37 37 40 41 43 44

5. COOLANT-SALT CHEMISTRY 5.1 Chemistry of Sodium Fluoroborate 5.2 Corrosion of Structural Alloys by Fluoroborates 5.2.1 Thermodynamics of Cr(III) in Fluoroborate

47 47 49 49

5.2.2 Metal Boride Formation 5.2.3 Corrosion of Nickel 6. DEVELOPMENT AND EVALUATION OF ANALYTICAL METHODS 6.1 In-line Analysis of Molten MSBR Fuel 6.2 Electroanalytical Studies of Bismuth in Molten LiF-BeF2 -ZrF4 6.3 Electroanalytical Studies in Molten NaBF4-NaF

50 51 52 52 56 57

PART 3. MATERIALS DEVELOPMENT 7. DEVELOPMENT OF MODIFIED HASTELLOY N 60 7.1 Procurement and Fabrication of Experimental Alloys 60 7.1.1 Production Heats 60 7.1.2 Semiproduction Heats 63 7.1.3 Laboratory Heats 66 7.2 Weldability of Commercial Alloys of Modified Hastelloy N 68 7.3 Stability of Various Titanium-Modified Hastelloy N Alloys 71 7.4 Mechanical Properties of Titanium-Modified Hastelloy N Alloys in the Unirradiated Condition73 7.5 Postirradiation Mechanical Properties of Modified Hastelloy N 79 7.6 Microstructural Analysis of Titanium-Modified Hastelloy N 83 7.6.1 Microstructure of Aged 503 and 114 Alloys 83 7.6.2 X-Ray Analysis of Precipitates 84 7.6.3 Irradiation and Creep Testing 84 7.6.4 Microstructure of Irradiated 503 and 114 Alloys 85 7.7 Salt Corrosion Studies 90 7.7.1 Status of Thermal-Convection Loop Program 90 7.7.2 Fuel Salt Thermal-Convection Loop Results 91 7.7.3 Forced-Circulation Loop Results 91 7.7.4 Coolant-Salt Technology Facility Results 94 7.7.5 Static Pot Tests 94 7.8 Corrosion of Hastelloy N and Other Alloys in Steam 94 7.9 Development of a Tellurium-Delivery System for a Representative Tellurium-Corrosion Screening Test Method 102 7.10 Reactions of Tellurium with Nickel at Low Tellurium Activities 102 7.11 Surface- and Grain-Boundary Studies Related to Hastelloy N Grain-Boundary Embrittlement 104 7.11.1 Development of Improved Techniques 104 7.11.2 High Temperature Studies of the Behavior of Tellurium in and on Experimental Alloys 104 7.12 Identification of Reaction Layers on Hastelloy N Exposed to Nickel Tellurides 105 7.12.1 Metallographic Examination 105 7.12.2 Electron Microprobe Analysis 105 7.12.3 X-Ray Diffraction Analysis 109 7.12.4 Conclusions 109 7.13 Examination of Hastelloy N Specimens Exposed to Tellurium 109 7.14 Operation and Analysis of TeGen-1 119 7.14.1 Operating History of TeGen-1 119 7.14.2 Data Analysis for TeGen-1 119 7.14.3 Future Irradiations 123 7.15 Examination of TeGen-1 123 8. FUEL PROCESSING MATERIALS DEVELOPMENT 8.1 Static Capsule Tests of Graphite with Bismuth and Bismuth-Lithium Solutions 8.2 Thermal Convection Loop Tests 8.3 Tests of Oxidation-Resistant Coatings on Mild Steel Pipe

137 137 140 141

PART 4. FUEL PROCESSING FOR MOLTEN-SALT BREEDER REACTORS 9. CHEMISTRY OF FLUORINATION AND FUEL RECONSTITUTION

150

10. ENGINEERING DEVELOPMENT OF PROCESS OPERATIONS 10.1 Installation of Metal Transfer Process 10.2 Salt-Metal Contactor Development: Experiments with a Mechanically Agitated Nondispersing Contactor in the Salt-Bismuth Flow-through Facility 10.3 Salt-Metal Contactor Development: Experiments with a Mechanically Agitated Nondispersing Contactor Using Water and Mercury 10.3.1 Theory 10.3.2 Experimental Results 10.3.3 Polaric Determination of Mass-Transfer Coefficients 10.4 Continuous Fluorinator Development 10.4.1 Autoresistance Ideating Test AHT-3 10.4.2 Design of Equipment for Autoresistance Heating Test AHT-4 10.5 Fuel-Reconstitution Development: Installation of Equipment for a Fuel-Reconstitution Engineering Experiment 10.6 Mass-Transfer Rates in Open Bubble Columns 10.6.1 Experimental 10.6.2 Effect of Liquid Velocity on KLa]d 10.6.3 Effect of Viscosity on KLa]d 10.6.4 Analysis of Previous Data 10.6.5 Correlation of Column Parameters 10.6.6 Conclusions 10.7 Conceptual Design of MSBR Fuel Processing Engineering Center

152 152 152 157 158 159 160 162 162 163 165 174 176 178 178 178 180 182 182

PART 5. SALT PRODUCTION 11. PRODUCTION OF FLUORIDE-SALT MIXTURES FOR RESEARCH AND DEVELOPMENT

184

ORGANIZATION CHART

187

ORNL-5078 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending August 31, 1975 SUMMARY PART 1 - MSBR DESIGN AND DEVELOPMENT 1. SYSTEMS AND ANALYSIS 1.1 Tritium Behavior in Molten Salt-Systems 1.1.1 MSBR Calculations 1.1.2 Coolant Salt Technology Facility 1.2 Xenon Behavior in MSBR 1.3 Neutronic Analysis 1.3.1 MSBR Studies 1.3.2 TeGen Capsules 1.4 High-Temperature Design Methods

2 2 2 3 8 9 9 12 12

2. SYSTEMS AND COMPONENTS DEVELOPMENT 2.1 Gas-Systems Technology Facility 2.1.1 Cavitation and Salt-Pump Shaft Oscillations 2.1.2 Salt-Pump Performance Data and Calibration of Variable-Flow Restrictors 2.1.3 Salt-Pump Fountain Flow 2.1.4 Densitometer Studies 2.2 Coolant-Salt Technology Facility (CSTF) 2.2.1 Loop Operation 2.2.2 Salt Mist Test 2.2.3 Tritium Experiments 2.3 Forced Convection Loops 2.3.1 Operation of MSR FCL-2b 2.3.2 Design and Construction of FCL-3 and FCL4

16 16 16 18 19 22 22 22 23 24 26 26 27

PART 2. CHEMISTRY 3. FUEL SALT CHEMISTRY 3.1 Compounds in the Lithium-Tellurium System 3.2 Spectroscopy of Tellurium Species in Molten Salts 3.3 The Uranium Tetrafluoride-Hydrogen Equilibrium in Molten Fluoride Solutions 3.4 Porous Electrode Studies in Molten Salts 3.5 Fuel Salt-Coolant Salt Interaction Studies 3.6 Lattice and Formation Enthalpies of First-Row Transition Metal Fluorides

29 29 30 31 32 34 37

4. COOLANT SALT CHEMISTRY 4.1 Chemistry of Sodium Fluoroborate 4.2 Corrosion of Structural Alloys by Fluoroborates

41 41 42

5. DEVELOPMENT AND EVALUATION OF ANALYTICAL METHODS 5.1 In-line Analysis of Molten MSBR Fuel 5.2 Tritium Addition Experiments in the Coolant-Salt Technology Facility 5.3 Electroanalytical Studies of Iron(II) in Molten LiF-BeFZ-ThF4 (72-16-12 mole %) 5.4 Voltammetric Studies of Tellurium in Molten LiF-BeFZ-ThF4 (72-16-12 mole %)

44 44 45 47 48

PART 3. MATERIALS DEVELOPMENT 6. DEVELOPMENT OF MODIFIED HASTELLOY N 52 6.1 Development of a Molten-Salt Test Facility 52 6.2 Procurement and Fabrication of Experimental Alloys 65 6.2.1 Production Heats of 2% Ti-Modified Hastelloy N 65 6.2.2 Semiproduction Heats of 2% Ti-Modified Hastelloy N Containing Niobium 69 6.3 Weldability of Commercial Alloys of Modified Hastelloy N 69 6.4 Stability of Various Modified Hastelloy N Alloys in the Unirradiated Condition 74 6.5 Mechanical Properties of Titanium-Modified Hastelloy N Alloys in the Unirradiated Condition78 6.6 Postirradiation Creep Properties of Modified Hastelloy N 82 6.7 Microstructural Analysis of Titanium-Modified Hastelloy N 84 6.7.1 Microstructural Analysis of Alloys 503 and 114 85 6.7.2 Homogeneous Hastelloy N Alloys 88 6.8 Salt Corrosion Studies 91 6.8.1 Fuel Salt Thermal Convection Loops 93 6.8.2 Fuel Salt Forced Circulation Loop 94 6.8.3 Coolant Salt Thermal Convection Loops 94 6.9 Corrosion of Hastelloy N and Other Alloys in Steam 97 6.10 Observations of Reactions in Metal-Tellurium-Salt Systems 100 6.11 Operation of Metal-Tellurium-Salt Systems 101 6.11.1 Tellurium Experimental Pot Number 1 101 6.11.2 Chromium Telluride Solubility Experiment 102 6.11.3 Tellurium Experimental Pot Number 2 103 6.12 Grain Boundary Embrittlement of Hastelloy N by Tellurium 103 6.13 X-Ray Identification of Reaction Products of Hastelloy N Exposed to Tellurium-Containing Environments 107 6.14 Metallographic Examination of Samples Exposed to Tellurium-Containing Environments 108 6.15 Examination of TeGen-1 119 6.15.1 Metallographic Observations 123 6.15.2 Chemical Analyses for Tellurium 124 6.16 Salt Preparation and Fuel Pin Filling for TeGen-2 and -3 131 7. FUEL PROCESSING MATERIALS DEVELOPMENT 7.1 Static Capsule Tests of Graphite with Bismuth and Bismuth-Lithium Solutions 7.2 Thermal Gradient Mass Transfer Test of Graphite in a Molybdenum Loop 7.2.1 Weight Changes 7.2.2 Compositional Changes 7.2.3 Microstructural Changes 7.2.4 Discussion of Results

132 132 133 133 133 137 137

PART 4. FUEL PROCESSING FOR MOLTEN-SALT REACTORS 8. ENGINEERING DEVELOPMENT OF PROCESSING OPERATIONS 8.1 Metal Transfer Process Development 8.1.1 Addition of Salt and Bismuth Phases to Metal Transfer Experiment MTE-3B 8.1.2 Run Nd-1 8.1.3 Run Nd-2 8.1.4 Discussion of Results 8.2 Salt-Bismuth Contactor Development 8.2.1 Experiments with a Mechanically Agitated Nondispersing Contactor in the Salt-Bismuth Flowthrough Facility 8.2.2 Experiments with a Mechanically Agitated Nondispersing Contactor Using Water and Mercury 8.3 Continuous Fluorinator Development

142 142 143 144 145 145 147 148 149 152

8.3.1 Installation and Initial Operation of Autoresistance Heating Test AHT-4 8.3.2 Design of a Continuous Fluorinator Experiment Facility (CFEF) 8.3.3 Fluorine Disposal System for Bldg. 7503 8.3.4 Frozen Wall Corrosion Protection Demonstration 8.4 Fuel Reconstitution Engineering Development 8.4.1 Instrumentation for Analyzing Reaction Vessel Off-Gases 8.4.2 Design of the Second Fuel Reconstitution Engineering Experiment 8.5 Conceptual Design of a Molten-Salt Breeder Reactor Fuel Processing Engineering Center

152 155 156 156 157 158 160 161

PART5. SALT PRODUCTION 9. PRODUCTION OF FLUORIDE SALT MIXTURES FOR MSR PROGRAM RESEARCH AND DEVELOPMENT 9.1 Quantities of Salt Produced 9.2 Operating Experience in 12-in.-diam Reactor 9.2.1 Charging and Melting of Raw Materials 9.2.2 Hydrofluorination and Hydrogen Reduction 9.3 Summary

163 163 163 164 166 166

ORGANIZATION CHART

167

ORNL-5132 MOLTEN-SALT REACTOR PROGRAM SEMIANNUAL PROGRESS REPORT For Period Ending February 29, 1976 INTRODUCTION

vii

SUMMARY

ix PART 1. MSBR DESIGN AND DEVELOPMENT

1. SYSTEMS AND ANALYSIS 1.1 TRITIUM BEHAVIOR IN THE COOLANT-SALT TECHNOLOGY FACILITY 1.1.1 Analysis of Experiments TI and T2 1.1.2 Analysis of Experiment T3 1.1.3 Analysis of Experiment T4 1.2 NEUTRONIC ANALYSIS 1.2.1 Cross Section Processing for MSBR Calculations 1.2.2 MSBR Performance Calculations 1.2.3 Helium Production in the MSBR Vessel 1.2.4 Production of 232U in the MSBR 1.2.5 Neutronic Analyses of TeGen Experiments 1.3 HIGH-TEMPERATURE DESIGN METHODS 1.3.1 Circular Cylindrical Shells 1.3.2 Nozzle-to-Spherical Shell Attachment 1.3.3 Nozzle-to-Cylinder Intersection 1.3.4 Inelastic Analyses of MSR Piping Subjected to Internal Pressure and Transient Temperature Cycles

2 2 2 3 5 7 7 9 9 10 12 12 13 13 13

2. SYSTEMS AND COMPONENTS DEVELOPMENT 2.1 GAS-SYSTEMS TECHNOLOGY FACILITY 2.2 COOLANT SALT TECHNOLOGY FACILITY 2.2.1 Loop Operation 2.2.2 Tritium Tests 2.2.3 Equipment Modifications 2.3 FORCED CONVECTION LOOPS 2.3.1 Operation of MSR-FCL-2b 2.3.2 Heat Transfer Studies in MSR-FCL-2b 2.3.3 Design and Construction of FCL-3 and FCL-4

15 15 16 16 16 18 19 19 21 22

13

PART 2. CHEMISTRY 3. FUEL-SALT CHEMISTRY 3.1 Solubility of Lithium Tellurides in Fluoride Melts 3.2 Spectroscopy of Telluride Species in Molten Salts 3.3 Decomposition Pressure of LiTe3 3.4 Porous Electrode Studies in Molten Salts - Electrochemistry of Tellurium in the LiCl-KCl Eutectic System 3.5 The Uranium Tetrafluoride-Hydrogen Equilibrium in Molten Fluoride Solutions

24 24 27 28

4. COOLANT-SALT CHEMISTRY 4.1 Hydrolytic Behavior of Na3B3F6O3

32 32

29 29

4.2 Vapor Density Studies in the System BF3-H2O 5. DEVELOPMENT AND EVALUATION OF ANALYTICAL METHODS 5.1 In-line Analysis of MSBR Fuel 5.2 Tritium Addition Experiments in the Coolant-Salt Technology Facility 5.3 Electrochemical Studies of Tellurium in Molten L1F-BeF2-ThF4 (72-16-12 mole %) 5.4 Electrochemical Studies of Oxygenated Species in Molten Fluorides

34 36 36 36 38 39

PART 3. MATERIALS DEVELOPMENT 6. DEVELOPMENT OF MODIFIED HASTELLOY N 42 6.1 Procurement and Fabrication of Experimental Alloys 42 6.1.1 Production Heats of 2% Titanium-Modified Hastelloy N 42 6.1.2 Semiproduction Heats of 2% Titanium-Modified Hastelloy N that Contain Niobium 45 6.2 Stability of Various Modified Hastelloy N Alloys in the Unirradiated Condition 45 6.3 Mechanical Properties of Modified Hastelloy N Alloys in the Unirradiated Condition 47 6.4 Postirradiation Creep Properties of Modified Hastelloy N 52 6.5 Microstructural Analysis of Modified Hastelloy N 59 6.5.1 Production of 2% Titanium-Hastelloy N Alloys with Uniform Carbide Distribution 59 6.5.2 Carbon Behavior in Ni-Mo-Cr-Ti Alloys 70 6.6 Salt Corrosion Studies 75 6.6.1 Thermal Convection Loop Results 76 6.6.2 Forced Circulation Loop Results 77 6.7 Corrosion of Hastelloy N and Other Alloys in Steam 80 6.8 Vapor Pressure Measurements of Metal Tellurides 85 6.9 Operation of Metal-Tellurium-Salt Systems 86 6.9.1 Tellurium Experimental Pot No. 1 86 6.9.2 Chromium Telluride Solubility Tests 87 6.9.3 Tellurium Screening Test 87 6.9.4 Ni3Te2 Capsule Test 87 6.9.5 Chromium-Tellurium-Uranium Interaction Experiment 87 6.10 Examination of a Hastelloy N Foil Sample Embrittled in the Molten-Salt Reactor Experiment 88 6.10.1 Sample History 88 6.10.2 Sample Fracture and Analysis Techniques 88 6.10.3 Observations 89 6.10.4 Discussion of Observations 93 6.11 High-Resolution Fractography of Hastelloy N Alloys Exposed to Tellurium 95 6.12 Metallographic Examination of Samples Exposed to Tellurium-Containing Environments 100 6.13 Salt-Tellurium Creep Studies 121 6.14 Salt Preparation and Fuel Pin Filling for MSR Program Capsule Irradiation Experiment TeGen-2 127 6.14.1 Salt Preparation 129 6.14.2 Hydrofluorination 130 6.14.3 U4+/U3+ Ratio Adjustment 132 6.14.4 Preparation of Salt Fill Vessel 132 6.14.5 Salt Transfer 132 6.15 Salt Preparation and Filling of TeGen-3 and -4 135 6.16 Operation of TeGen-2 and -3 136 6.16.1 Operating History of TeGen-2 and -3 139 6.16.2 Data Analysis for TeGen-2 and -3 139 6.16.3 Preliminary Results of TeGen-2 141 6.16.4 Future Irradiations 142 6.17 Examination of TeGen-2 143

7. FUEL PROCESSING MATERIALS DEVELOPMENT 7.1 Summary of Compatibility Studies 7.1.1 Ta-10% W Thermal Convection Loop Test 7.1.2 Dissimilar Material Tests

163 163 163 163

PART 4. FUEL PROCESSING FOR MOLTEN-SALT REACTORS 8. CHEMISTRY OF FLUORINATION AND FUEL RECONSTITUTION

170

9. ENGINEERING DEVELOPMENT OF PROCESSING OPERATIONS 9.1 Metal Transfer Process Development 9.1.1 Entrainment Studies in Experiment MTE-3B 9.1.2 Removal of LiCl and Bi-Li Phases and Addition of Purified Solutions 9.1.3 Experiments Nd-3 and Nd-4 9.1.4 Results 9.2 Mass-Transfer Studies Using Water-Mercury Contactors 9.2.1 Experimental Equipment and Procedure 9.2.2 Experimental Results 9.3 Continuous Fluorinator Development 9.3.1 Autoresistance Heating Test AHT-4 9.3.2 Frozen-Salt Corrosion Protection Demonstration (FSCPD) 9.4 Fuel Reconstitution Engineering Development 9.4.1 Hydrodynamic Operation 9.4.2 Calibration of the UF6 Metering System 9.4.3 Calibration of Ar-UF6 Gas Density Detector 9.4.4 Calibration of the HF-H2 Gas Density Cell

172 172 172 173 173 174 177 178 179 184 185 186 189 191 192 192 193

PART 5. SALT PRODUCTION 10. PRODUCTION OF FLUORIDE SALT MIXTURES FOR RESEARCH AND DEVELOPMENT

197