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Contract No. W-7405 -eng-26

Reactor Division

DEVELOPMENT OF FUEL- AND COOLANT-SALT CENTRIFUGAL PUMPS FOR THE MOLTEN-SALT REACTOR EXPERIMENT

P. G. Smith

LEGAL NOTICE

This report

was prepared as an account of work

sponsored by the United States Government. Neither the United States nor the United States Atomic Energy Commission, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied. or assumss m y legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights.

OCTOBER 1970

,QAK R I E E NATIONAt LABORATORY

Oak Ridge, Tennessee operated by

UNION CARBIDE CORPORATION f o r the U.S. ATWIC ENERGY COMMISSION

mON OF THIS DOCuEmT IS 1

-4 c

iii

CONTENTS &

6;-

Page -

....................................................... General Description of the Molten-Salt Pump ....................

1 2

Test Apparatus Molten-Salt Pump Test Stand

Abstract

............................... Molten-Salt Properties ....................................

Beach Tests and Cold Shakedown Tests Force-Deflection Characteristics of Shaft Critical Speed of Shaft Assembly

*.* L

................. .......................... Room-Temperature D r y Runs ................................. Molten-Salt Tests .............................................. Hydraulic Performance ..................................... Cavitation Performance .................................... Effectiveness of Shaft Annulus Purge Against Back Diffusion of Radioactive Gas ....................................... Measurement of Undissolved Gas Content in Circulating Salt Problems Encountered During Pump Fabrication and Molten-Salt Tests

............................................. Fabrication Fâ&#x20AC;&#x2122;roblems ...................................... Shaft Annulus Plugging .................................... Insufficient Running Clearances ........................... Oil Leakage from the Catch Basin into the Pump Tank ....... Pump Tank Off-Gas Line Plugging ........................... Failure of Weld Attachment of P a r t s of Flow-Straightening Device ................................................... Mark-2 Fuel-Salt Pump .......................................... Description of Pump ....................................... Hydraulic Performance ..................................... Measurement of Undissolved Gas Content in Circulating salt Restrictions to Purge-Gas Flow

..................................................... ............................. Performance of Molten-Salt Pumps in MSRE ....................... Conclusions .................................................... Acknowledgments ................................................

9 9 11

11 11

14 14 17 21 22

24 26

28 33 33 36

36 36 38

40 40

iv References Appendix.

...................................................... MSRE Drawings ........................................

41 43

DEVELOPMENT OF FUEL- AND COOLANT-SALT CENTRIFUGAL PUMPS FOR THE MOLTEN-SALT REACTOR EXPERIMENT

P. G. Smith Abstract The Molten-Salt Reactor Experiment (MSRE), a small nuclear power reactor that produced about 7 Mw of heat while operating at approximately l225'F and atmospheric pressure, requires a pump in each of two circulating molten-salt systems. A vertical centrifugal sump-type pump was developed for each system through water and molten-salt tests of prototype pumps at temperatures to 1400'F and hot shakedown operation of the actual reactor pumps before they were qualified for reactor service. The development experience with the pumps in the molten-salt pump test stand and the performance of the reactor pumps in the MSRE are discussed here. The hydraulic performance of the pumps circulating molten salt corresponded closely with the performance obtained with water. The reactor pumps served well throughout the approximately 30,OOO-hr operating life of the MSRE, which spanned the period August 1964 to December 1969, during which the reactor produced 105,737 Mwhr(t) of nuclear energy. A backup pump (Mark-2), which contains additional volume in the puplp tank to accommodate thermally expanded salt, was also fabricated and tested for the MSRE. Keywords: pump, molten salt, Molten-Salt Reactor Ekperiment, centrifugal pump, sump-type pump, high temperature, nuclear reactors, pump hydraulic performance, water test Pump

A centrifugal pump was developed for circulating molten salt at ele-

vated temperatures in the Molten-Salt Reactor Experiment (MSRE) Briefly, the MSRE is a salt-fue ite-moderated single-region nuclear reactor test facility with a heat-generation rate of approximately 7 Mw(t) Two salt pumps are required, one in the fuel-salt loop and the other in the

coolant-salt loop. Since t

signs of the two pumps are essentially identical, primary attention is given here to the fuel-salt pump. The pump is a vertical-shaft sump pump with an overhung impeller and an oil-lubricated face seal. It was developed through a series of bench tests, water tests,S cold shakedown operations, and high-temperature

molten-salt t e s t s

The problems encountered during development and

u f

t e s t i n g and the r e s u l t s of pump operation a t ambient and elevated tem-

peratures (up t o lbO째F) a r e discussed i n t h i s report.

Hydraulic per-

formance data, priming conditions, and coastdam c h a r a c t e r i s t i c s were obtained, and the effectiveness of spray devices f o r xenon removal was demonstrated. Thermal-stress and strain-fatigue analyses' '

were made f o r the pump

tanks of both the fuel- and coolant-salt pumps. They were made f o r an estimated operating history t h a t included 100 heating cycles from room temperature t o 1200OF and 500 reactor power change cycles from zero t o

full power. The calculations indicated t h a t a cooling air f l a w r a t e of 200 cfm was required f o r t h e f u e l pump tank, while t h e coolant pump tank w a s capable of t h e required service without air cooling. The pattern followed in t h e development of these pumps and t h e design of a similar pump were discussed elsewhere i n some d e t a i ~ . ~ The problems and tests required f o r developing other s p e c i f i c elevatedtemperature pumps have been reported.6ao

Fuel- and coolant-salt pumps were i n s t a l l e d i n the appropriate salt c i r c u i t s of t h e ERE, where they each circulated salt o r helium a t e l e vated temperatures f o r a t o t a l of approximately 30,000 hr.

The reactor

was operated up t o f u l l power and was recently shut dawn permanently. During operation of t h e reactor, which produced 105,737 Mwhr(t) of nuc l e a r energy, t h e lubricants f o r t h e bearings and s e a l s and t h e insul a t i o n f o r t h e drive motor were exposed t o a nuclear radiation environment The numbers of t h e drawings f o r t h e f u e l - and coolant-salt pumps, t h e drive motors, t h e lubrication stand, and the Mark-2 f u e l - s a l t pump

are l i s t e d i n t h e Appendix. General Description of the Molten-Salt Pump The pump is of t h e centrifugal sump type with a v e r t i c a l s h a f t . It consists of three main components: and t h e drive motor (see Fig. 1 ) .

the pump tank, t h e r o t a r y assembly,

The t h r e e main components a r e bolted

ORNL-LR-OWQ-56043-BR2

LUBE OIL BREATHER LUBE OIL I N BALL BEARINGS (Face to Face) BALL BEARINGS I Back to Back 1 LUBE OIL OUT SEAL OIL LEAKA

BEARING HOUSING GAS PURGE I N SHAFT SEAL ( S e e Inset SHIELD COOLANT PASSAGES ( I n Parallel With Lube Oil ) SHIELD PLUG

LEAK DETECTOR

GAS PURGE OUT (See Inset) GAS FILLED EXPANSION

To Overflow Tank

F i g . 1.

Cross Section of Fuel-Salt Pump.

BASIN

4 together and sealed with oval ring-joint gasketed flanges. The ringj o i n t grooves are connected t o a le&-detection system. The motor and r o t a r y assembly may be removed from t h e pump tank e i t h e r as a u n i t o r separately. Hastelloy N,*

A l l p a r t s i n contact with molten salt are constructed of

a nickel-molybdenum-chromium-iron a l l o y .

The pump tank, which provides volume t o accommodate t h e thermally

expanded salt of t h e system, contains t h e pump volute o r casing, t h e xenon-removal spray device, t h e salt l e v e l indicators, and various access nozzles. The r o t a r y assembly consists p r i n c i p a l l y of t h e bearing housing; t h e pump shaft, which i s mounted on commercially available conventional b a l l

bearings; the shaft seals, which constrain t h e c i r c u l a t i n g l u b r i c a t i n g o i l from leaking out of t h e bearing housing; t h e s h i e l d plug, which i s cooled with c i r c u l a t i n g o i l ; and t h e pump impeller.

The s h i e l d plug and

other p a r t s of t h e rotary assembly t h a t come i n contact w i t h t h e s a l t are suspended i n t h e pump tank through a l a r g e flanged nozzle a t t h e t o p

of t h e tank.

The drive, which i s housed i n a hermetically sealed vessel, is a squirrel-cage induction-type motor rated f o r 75-hp duty a t 1200 rpm. The e l e c t r i c a l insulation system i s r e s i s t a n t t o a r a d i a t i o n dose of up

t o le rads and the grease lubricant i s reportedâ&#x20AC;&#x2122;l t o be capable of w i t h standing a dose of more than 3 X le rads.

The pump has some unusual features required by i t s application t h a t are not found i n t h e conventional sump pump. salt-spraying device t o remove

135Xe

The pump tank contains a

(neutron absorber) from t h e circu-

l a t i n g fuel salt and a l s o has two gas-bubble sensors t o indicate s a l t level.

The spray device is connected t o t h e volute discharge, from which

it receives a proportioned flow of about 50 gpm of s a l t at pump design head and flow. This flow and other leakage flows (bypass f h w ) pass through the pump tank and return t o t h e system a t t h e pump i n l e t . A s p l i t purge-gas flow i n t h e shaft annulus keeps o i l vapors from entering t h e salt system and f i s s i o n gases from entering t h e region of t h e shaft *Hastelloy N, known a l s o as INOR-8 and Allvac N, has t h e b a s i c composition, by weight, 15-18s Mo, 6 8 %C r , 5 s Fe (max), 0.60.8$ C, balance N i .

5 lower seal. The down-the-shaft portion of the purge-gas flow removes ,. lesXe- by contact with the salt- spray and dilutes and transports it from the pump tank to the 'off-gas system. The pump is mounted on a flexible support designed to accommodate thermal expansions. A flow of nitrogen across the exterior of the upper nonwetted portion of the pump tank removes nuclear heat deposited in the tank wall. The bolt extensions, which can be seen in Fig. 2, provide for remote installation of the drive motor and rotary assembly in the MSRE.

and removal

Test Apparatus Molten-Salt

Pump Test Stand

A schematic view of the test stand components is shown in Fig. 3. The components include the drive motor, the test pump, and the salt piping, which is 6-in. IPS sched 40, except for a section of pipe at the pump inlet, which is &in. IPS sched 40. Other components include a venturi flowmeter, the heat removal system, a drain tank for salt storage, the preheating system, a flow straightener, high-temperature pressure and temperature sensors, the lubrication system,ls and two salt freeze flanges, one of which provides a place to mount an orifice plate to set the system resistance to salt flow. The system resistance was varied with four orifice plates having different hole diameters. The heat removal system, tihich is a salt-to-air heat exchanger, was used to control the salt temperature. The~drain tank stored the fluoride salt in the Commercial diaphragmmolten state when the system-was not in operation. sealed NaK-filled pressure transmitters.were used to indicate pressure at the pump discharge and at the inlet and throat of the venturi. Transformer controlled heaters were used to preheat the salt piping and 'cornponents, and Chromel-Alutnel thermocouples monitored the system.temperatures. Conventional instrumentation &s used to_display and; record temperatures, salt flow, pumi drive motor 'poi;er, and salt level in the pump .~ tank. A photograph of the test facility, Fig.â&#x20AC;&#x2DC; 4, shows the pumpâ&#x20AC;&#x2DC;in the left upper foreground, a portion of the salt piping beneath and to the rear of the pump, and a portion of the control cabinets;

Fig. 2. Fuel-Salt Pump Drive Motor, Rotary Assembly, and Bolting f o r Remote Maintenance.

ORNL-LR-DWG

-L-r’.

/THERMAL

72414

l-t---l

PIPE HEATER x -8-in.

PIPE

FLANGE4 VENTURI METER,

,6-h

PIPE

I -FLOW MSRE FREEZE FLANGE

Fig.

Schematic Diagram of Molten-Salt

Pump Test Stand.

ST RAIGHTENER

a c al 4J

4 Q

9 -2

<+**

Molten-Salt Properties The molten salt used for pump tests was a mixture of lithium fluoride ( LiF) , beryllium fluoride (BeF, ) , zirconium fluoride ( ZrF, ) , thorium fluoride (ThF,), and uranium fluoride (m4) in proportions of 66.4, 27.4, 4.7, 0.9, and 0.7 mole 8, respectively. The mixture is solid at room temperature and melts at approximately b50'~. The density13 and viscosity14 at three temperatures of interest are given below:

Temperature ( OF)

Density 0bm/ft3 1

Viscosity ( CPS 1

1100

132

1200

130

1300

129

Bench Tests and Cold Shakedown Tests Force-Deflection Characteristics of Shaft The force-deflkction characteristics of the shaft were measured with the shaft assembly supported in the bearing housing and with the force applied at the,impeller. A typical curve of shaft deflection at the impeller versus force is shown in Fig.

5. This information and

deflection data obtained during water tests were used to determine the

unbalanced force-vector acting on the impeller at various head, flow, and speed operating conditions.16 The force values were used to analyze shaft bending stresses and bearing reactions and to specify the shaft support bearings. Critical Speed of Shaft As The critical sheed of each shaft assembly was determined by vibrating the shaft assembly in the ansverse direction. The shaft assembly was supported in the bearing housing and mounted vertically on a rugged-steel structure anchored to the building floor. The vibrating force was applied at the impeller and held constant Over a range of applied frequencies.

10 , .

w .

. 9

ORNL-DWG 70-6823

10-31

30 E . I Y

EI-:

o 20 W 2

L W

Fig. 5 . of Pump.

100

200 300 FORCE ( l b )

400

500

Shaft Deflection Versus Radial Force Applied t o Impeller

Data were obtained f o r frequency versus vibration amplitude.

The c r i t i c a l

speed determined by t h e frequency a t which t h e amplitude increased sharply checked quite closely with the calculated value.

For t h e f u e l - s a l t pump

the value w a s calculated t o be 2850 rpm and was measured t o be within 100 rpm of t h i s value.

Room-Temerature Drv Runs After assembly a pump rotary element i s normally operated f o r about one week o r longer i n a cold shakedown stand before i n s t a l l a t i o n i n t h e hot t e s t stand.

This operation i s conducted t o v e r i f y t h a t t h e element

i s f r e e of mechanical problems and t o t e s t t h e performance of t h e shaft

bearings and s e a l s .

The o i l leakage from a properly performing shaft

s e a l is usually 10 cc/day o r less.

Molten-Salt Tests

Tests with molten salt were conducted with t h e prototype and r e actor pumps t o (1)verify the hydraulic performance observed i n the water t e s t s , (2) determine t h e effectiveness of t h e gas purge down t h e s h a f t annulus against t h e intrusion of radioactive gas, (3) measure t h e concentration of undissolved gas i n the circulating salt, (4) perform acceptance tests of the reactor pumps p r i o r t o t h e i r i n s t a l l a t i o n i n t o t h e reactor system, and ( 5 ) t e s t t h e overall long-term r e l i a b i l i t y of t h e pump and drive motor a t design and off-design conditions.

Table 1

presents a summary of t h e molten-salt t e s t operation of t h e prototype pump, t h e r o t a r y elements f o r t h e reactor pumps, and t h e Mark-2 f u e l -

salt pump. 3ydraulic Performance Hydraulic performance

sts were conducted with l3-in.- and 11 1/2-in.-

OD fuel pump impellers i n t h e molten-salt pump t e s t stand with t h e fuel-

salt pump tank and volute i n s t a l l e d ,

The head-capacity performance of the

13-in.-OD impeller with both water and molten s a l t i s shown i n Fig. 6, i n which the head i s plotted against flow f o r t h r e e t e s t speeds. A t 1030 rpm,

Shakedam test of prototyp b l -

Ey&uulic perfoneace test or prototype rue1-salt pnnp

s.slt pnnp

Scheduled

above

variable rrequency motor-generstor set W u r e

Bamc aa above

B S C J L - ~ ~ ~ tests ~ B ~ O or~

Oaa-COnCentrstion tests in circulatlng Mlt ma bach-ditluslca tests or prototype ruei-salt

Das-concentration tests of prototype -1-salt pmrD in circulating salt

Ey&uulic perfoneace of prototype fuel-salt pump

Roor test

prototype

iUc1-salt pnnp

Variable frequency motor-generator set failure Scheduled

of lubrication stand

ana fuel EUmp supports Scheduled

7 8

Roof test of coolant p m r ~lubrication Stand Ma fuel pzmp .up

Scheduled

Reactor iuel pnnp hot shakedown test

Shaft rubbed at startup

Reactor coolant pnnp hot shahe-

Scheduled

Reactor fuel test

Reactor sparc -1 down test

Reactor s w e coalant pump hot shakedovn test

Reactor spare fuel pnnp hot shakedovn, back-diffusim, gas ccmcentratim testa

Reactor apere fuel-pump impeller sbabcdovn tests

Bchedulea

Reactor spare coolant drive motor shakedm tests

Scheduled

prototype rue1 PJmP test

SChedul&

Reactor spare tuel p m r ~hot ~babsdovn tests

Scheduled

Reactor spare coalant

P a r f m c e d endurance tests of hhk-2 Pmrp

down test plmp

hot shakedam pnnp hot shake-

p m r ~hot

shakedown teats

Scheduled

m e r rubbed volute Scheduled

bd a

ORNL-DWG 65-6666

40 I

c .c

30 I c

s' I

ALLIS-CHALMLRS SIZE 8 x 6 ; TYPE ORNL .~ DATA POINTS:

200

400

I MFG. CO. IMPELLER AND VOLUTE DESIGN E ; IMPELLER P 4 8 2 , 13-in. OD WATER PERFORMANCE ORNL MOLTEN SALT PERFORMANCE AT 42OOOF

600

800

1000

I200

1400

1600

1800

0,FLOW (gal/min) Fig. 6.

Hydraulic Performance of Prototype Fuel-Salt Pump with Water

and with Molten Salt.

14 t h e molten-salt head varies as much as 1 1/2 f t from t h a t of water, and

a t 860 and 700 rpm t h e head f o r t h e molten salt i s low by approximately 1f t .

Cavitation Performance The NPSH requirements f o r t h e pumps, as reported by t h e manufacturer of t h e hydraulic components (volutes and impellers), are 5.5 and 11 ft, respectively, f o r t h e fuel- and coolant-salt pumps at t h e i r operating conditions.

Converted t o pressure of t h e c i r c u l a t i n g salt t h e NPSH values

are 5 and 10 psia, respectively.

These pressures a r e below atmospheric,

and evacuation of t h e pump tank gas space would be required t o investigate t h e suction pressure a t which cavitation sets i n .

Sinceevacuation i s

required t o cause cavitation and t h e operating pressure of t h e pump tanks i n t h e E R E i s 5 psig, experimental investigations of c a v i t a t i o n inception

were considered unnecessary and therefore were not performed. Effectiveness of Shaft Annulus k g e Against Back Diffusion of Radioactive G a s

The migration of radioactive gases from t h e pump tank t o t h e region of t h e s h a f t lower seal v i a t h e shaft annulus could result i n polymerizat i o n of t h e o i l t h a t leaks past the seal and lead t o plugging of t h e d r a i n

l i n e from t h e o i l catch basin.

To minimize t h i s migration, a flow of

helium purge gas was introduced down the s h a f t annulus.

Figure 7 i s a

schematic diagram of the s h a f t annulus configuration and the purge-gas

f l o w paths.

The upper end of t h e f l o w path f o r t h e dam-the-shaft purge

contains a labyrinth s e a l (not shown), which has a 0.005-in.

diametral

clearance.

In back-diffusion t e s t s , pump tank as shown.

and nitrogen were i n j e c t e d i n t o t h e The concentrations of 85Kr i n t h e pump tank off-gas 85-

l i n e and i n t h e l i n e from t h e leakage-oil catch basin were determined with count-rate meters f o r various flow rates of purge gas.

The data f

shown i n Table 2 were obtained during t h e t e s t s .

The

85Kr

was not de-

t e c t e d i n the purge gas f r o m t h e catch basin even with a count rate meter capable of detecting a concentration as s m a l l as 0.95 x l o-''

Ci/cn?.

LiiJ

15 ORNL-DWG 63-6482

16 These data indicate the capability of the purge gas at flow rates of approximately 0.25 liter/min to reduce the concentration of *6Kr in the catch basin by a factor as much as 35,000 times below the concentration in the pump tank.

Table 2. Back-Diffusion Test Results IDimeCrstl clearance: 0.005 in.

Shaft Purge ( liters/day)

Catch Basin Purgea ( liters/day)

SSKr

Concentration in hunp Tank (Ci/cl#)â&#x20AC;&#x2122;

487

0 .trg

u7 497

0.m

481

2077

354 360 360 673 360

3.28 1.85

0 075

681

o.go

681

3054

2.06 e

1.21

1.65

concentration in catch basin was less than

0.95 x 10-lâ&#x20AC;&#x2122; at all purge flows.

The maximum permissible concentration of radioactive gases in the catch basin to avoid polymerization of the leakage oil was calculated to be 3.1 X lo-+ Ci/cxrP. Calculations based on this limitation and the data of Table 2 indicate a maximum permissible concentration or radioactive gases of 2.4 to 11.0 Ci/cnP in the pump tank. The results of additional calculations relating the flow rate of purge gas in the damthe-shaft annulus to the concentration of radioactive gases in the pump

tank for a conservative assumption of the MSRE nuclear operating condi-

tions are presented in Fig. 8 . This figure indicates that a flow rate of purge gas of less than 1 liter/min suffices to protect the seal oil

leakage in the catch basin from polymerization by radioactive gases. A satisfactory supply of purge gas was available at the MSRE.

Additional back-diffusion tests were made with esKr injection in which the shaft ~tnnuluslabyrinth seal clearance was 0.010 in., and the data obtained are given in Table 3. With a detector sensitivity of 1.5 x 10-l' Ci/cI#, SSKr could only be detected in the catch basin at low down-the-shaft purge flow rates. Table 3. Back-Diffusion Test Results Diametral clearance: 0.010 in.

Shaft Purge (liters/day1

Catch Basin bge ( liters/day)

2 32

173 164

105

212

*5Kr

Concentration (Ci/cS 1

In Pump Tank

2.66 x 5.50 x lo-' 4.24 x IO-'

Ip Catch Basin

d . 5 x lo-'* d . 5 x lo-' ~8.17x lo-*

Measurement of Undissolved Gas Content in Circulating Salt s bubbles in the pump tank liquid can Undesirable quantiti be entrained in the circ s a l t by the return of salt that has leaked into the pump tank from the high-pressure side of the pump. The

high velocity of these salt leaks from the internal spray and other carry gas under the salt surface. The sources within the pump t ng salt may then carry the bubbles to downward velocity of the the impeller inlet and on the circulating salt.

To obtain inslght i

the concentration of undissolved gas

in the circulating salt was measured by using gamma radiation densitometry.

ORNL-DWG 63-6483

10 Mw POWER 100 % STRIPPING EFFICIENCY 50 gpm BYPASS FLOW 5 psig PUMP TANK PRESSURE

0 0

I000 2000 3000 4000 PUMP TANK PURGE ( liters/day)

5000

Fig. 8. Concentration of Radioactive Gas Versus Purge-Gas Flow Rate i n Prototype Fuel-Salt Pump.

A 40-Ci 1s7Cs source of 0.622-Mev gamma rays was placed on one side of

t h e salt piping a t t h e pump i n l e t , a region of low s t a t i c s a l t pressure, and a radiation detector was placed on t h e other side.

The detector

consisted of a cylinder of p l a s t i c phosphor ( 3 i n . i n diameter and 6 i n . long) and an electron multiplier phototube.

The p l a s t i c phosphor absorbs

photons, which a r e transmitted from t h e source through the salt.

Light

i s emitted by the p l a s t i c phosphor t o a phototube that produces a current. The current i s a f'unction of t h e photon transmission through t h e salt, which i n t u r n i s an Inverse function of t h e density of t h e salt.

The

signal current from t h e detector i s fed t o a suppression c i r c u i t t h a t indicates only variations i n the current. recorded on Visicorder tape.

The current indication i s

Thus an increase i n t h e concentration of

undissolved gas, which causes a decrease i n salt density, i s indicated by an increase i n the current output of t h e densitometer. The densitometer was calibrated over a small range of thermal change

i n salt density corresponding t o t h e salt temperature range 1100 t o

1400'F.

During calibration t h e s a l t contained no entrained gas.

The

pump was not operating, s o gas bubbles could leave t h e densitometer and enter the higher elevations i n the salt system.

Thermal-convection

v e l o c i t i e s i n the salt were too small t o e n t r a i n fresh gas from t h e pump

tank. The two Visicorder t r a c e s shown i n Fig. 9 give a measure of helium concentration i n t h e salt loop a t two d i f f e r e n t salt l e v e l s i n t h e pump tank.

The pump was operated with a 13-in.-OD impeller at a flow of

1650 gpm through t h e 6-in,-diam pipe and a salt temperature of '1185 OF; approximately 85 gpm of s a l t was bypassed through the spray ring. The curves are plotted with t h e flow density a t zero deflection f o r comparison and t o i l l u s t r a t e t h e t r a n s i e n t behavior of t h e gas concentration when t h e pump i s f i r s t stopped (flow reduction t o zero) and then started (flow increase from 0 t o 1650 gpm)

Trace I presents t h e density data

f o r t h e normal l e v e l of s a l t i n t h e pump tank ( 3 3/8 i n . above center ! 3

l i n e of t h e volute).

Trace I1 relates t o a higher salt l e v e l i n t h e

pump tank ( 4 7/16 i n . above t h e center l i n e of t h e volute).

The gas

ig,

concentration i n t h e circulating salt when operating a t t h e normal l e v e l was 4.6 vol $, and a t t h e other higher l e v e l it w a s 1.7 vol $. The

ORNL-OWG 65-11798

9 E

6 5

-az 4 >

0 3

Y2 LL w 4 0

0 SALT TEMPERATURE: 1185OF

-1

-2 -3

-4 0

io0

420

440

460

480

200

TIME (sec)

F i g 9. Concentration of Undissolved Gas Versus Time as Determined by Gamma Radiation Densitometry of Prototype Fuel-Salt Pump with 13-in. Impeller and 1650-gpm Salt Flow.

sensitivity of the Visicorder was 0.64 vol $ per division. At the higher operating level, the discharge ports of the xenon removal spray ring were covered with salt. Since the high-velocity spray from the xenon-removal spray ring is a major contributor to the agitation that causes gas bubbles, it is understandable that the gas concentration was lower when operating at the higher level in the pump tank. In a separate test, the same densitometer arrangement was used to measure gas concentrations in the fuel salt circuit at the MSRE. The principal conditions included the impeller diameter of 11 1/2 in., a salt flow of 1150 gpm at 1200째F, normal operating level, and a spray-ring flow of 50 gpm. The void fraction in the salt was not detectable at these conditions. At a lower level of salt in the pump tank, a void fraction of 2 to 3 vol $ was indicated. Subsequent measurements with the same densitometer on the molten-salt test loop and with a 11 1/2-in.-diam impeller, a flow of 1200 gpm at 1200째F, the salt at the normal operating level, and a spray-ring flow of 50 gpm gave a void fraction of 0.1 vol $. Comparing the gas concentrations for operation with the l3-in.- and the 11 1/2-in.-diam impellers at the normal operating level shows that the content is less with the smaller impeller by a factor of 46. This is attributable to the xenon-removal spray flow, which is approximately

50 gpm for the smaller impeller, compared with 85 gpm with the 13-in.-diam impeller. The jet velocity from the spray ring is considerably less with the 50-gpm flow; thus there is less agitation of the liquid level surface upon impingement of the jet streams.

Fabrication problems were encountered with the dished heads for the pump tanks, the impeller and volute castings, and the hermetic vessels for enclosing the drive motors. Pump operating problems were encountered with the shaft purge flow, shaft and impeller running clearances, shaft seals, and the flow straightener in the test stand salt piping during testing and operation of the pumps at elevated temperatures.

22 Fabrication Problems c

The Hastelloy N dished heads f o r t h e pump tanks were originally fabr i c a t e d by hot spinning of p l a t e stock.

The r e s u l t i n g heads contained

many crack-like defects on the knuckle radius t h a t were readily detectable

by dye-penetrant inspection.

However, t h e heads were repaired by removal

of the cracks by grinding, and t h i s rendered them usable f o r t e s t purposes. Later, during fabrication of t h e reactor pumps, t h e problem was solved by hot pressing t h e p l a t e stock. Considerable e f f o r t and t i m e were expended t o obtain s a t i s f a c t o r y Hastelloy N castings f o r the impellers and volutes.

The i n i t i a l castings

were unsatisfactory due t o defects such as cracks r e s u l t i n g from shrinkage, inclusions, and porosity.

Castings of improved quality, which were accept-

able a f t e r repairs, were obtained from a second foundry.

The castings were

improved by modifying the chemistry of t h e casting melts and by the founder giving close supervision and a t t e n t i o n t o t h e d e t a i l s of t h e casting pro-

cedures.

Two problems were encountered during the fabrication of t h e hermetic a l l y sealed vessels f o r the drive motors.

The design o r i g i n a l l y specified brazing a cooling c o i l of stainless s t e e l pipe t o t h e outside of the cylind r i c a l carbon s t e e l vessel.

However, because of t h e difference i n thermal

expansion between the two materials, continuous attachment of t h e c o i l t o t h e vessel was not achieved by brazing. t h e c o i l i n place.

The problem was solved by welding

A more serious problem was encountered during t h e build-

up of weld metal, "buttering," on t h e inner surface of the vessel t o accommodate t h e attachment of a f l a t head.

Large laminar defects appeared i n

t h e vessel w a l l i n the region of the buildup. grinding and weld r e p a i r resolved t h e problem.

Removal of t h e defects by Satisfactory vessels were

obtained but a t t h e expense o f delays i n delivery of t h e vessels and additional expense t o the fabricator.

Shaft Annulus Plugging During t e s t 6 (see Table 1) t h e recorded t r a c e of drive motor power began fluctuating a f t e r

700 hr of operation with molten salt at 120O0F,

An anomalous value of gas pressure, which exceeded t h e supply pressufe

23 by approximately 5 p s i , was observed i n the pump tank.

The t e s t was

therefore terminated, and inspection of t h e rotary assembly revealed t h e presence of s o l i d i f i e d s a l t i n the annulus between pump s h a f t and s h i e l d plug. I Subsequent analysis showed t h a t the gas flow i n t h e lower portion of the shaft annulus had been reversed and w a s upward instead of downward, t h e proper direction.

The flow reversed because the gas flow

from t h e l i q u i d l e v e l indicators, although thought t o be s m a l l , w a s actually significant.

The excess gas exceeded the t h r o t t l e d capacity

of the off-gas flow l i n e from the pump tank; consequently t h e excess gas flowed upward, joined t h e annulus purge gas, and l e f t the pump through t h e s h a f t seal o i l leakage drain l i n e .

Small droplets of molten salt were c a r r i e d by the reversed purge flow i n t o t h e lower end of t h e .

s h a f t annulus where they s o l i d i f i e d , accumulated, and f i n a l l y acted as

a brake on the s h a f t .

The chemical composition of a sample of t h e mate-

r i a l taken from t h e s h a f t annulus was very close t o t h a t of the salt being circulated. The r e s u l t s of x-ray and petrographic examinations of t h e sample indicated t h a t t h e material w a s carried i n t o t h e annulus as an aerosol.

To prevent t h e recurrence of t h i s incident and t o provide protection against back diffusion, t h e flow r a t e s of t h e gas t o and from t h e pump tank were monitored more closely t o assure t h a t purge gas did flow down

the shaft annulus.

The flow rate of gas from t h e pump tank must equal

t h e flow r a t e of t h e purge

t h e shaft annulus plus t h e flow r a t e of

gas associated w i t h t h e op

n of t h e bubble-type l e v e l indicators.

Another case of s h a f t annulus plugging was encountered during t e s t

17 (see Table 1). The plugging was indicated by a buildup of pressure i n t h e seal o i l leakage catch basin compared w i t h t h e pump tank pressure.

The pressure d i f f e r e n t i a l u t of t h e catch basin i n t o the pump tank. sampling t h e pump tank off of t h e s h a f t annulus, and it

s i ) thus created caused o i l t o leak t h e outer surface of t h e s h i e l d plug and age was detected by a hydrocarbon analyzer

e plug w a s located a t t h e lower end of such a nature it could be temporarily

removed by heating t h e system circulating salt from 1200 t o 1250째F or by

24 stopping t h e pump b r i e f l y and then r e s t a r t i n g it.

The pressure d i f f e r -

e n t i a l between the catch basin and pump tank would disappear, and leakage of o i l would stop as indicated by t h e hydrocarbon analyzer.

After termi-

nation of the t e s t , material from t h e plug was analyzed and found t o be of a composition similar t o the t e s t salt. The o r i g i n a l salt deposit i s believed t o have resulted from a f i l l i n g operation of t h e system wherein t h e supply of salt i n the dump tank was depleted before reaching the normal l e v e l i n t h e pump tank. G a s then bubbled up through t h e dip-line connecting the dump tank t o t h e

salt piping and rose i n t o t h e pump tank, where it erupted from t h e surface and splashed salt against the lower end of the s h i e l d plug.

The tempera-

ture of t h e surface was l o w enough t o freeze t h e salt and r e t a i n it. Insufficient Running Clearances

It i s normal practice t o t r y t o operate centrifugal pumps a t or near t h e i r highest efficiency.

During operation along t h e constant sys-

tem flow-resistance curve t h a t passes through t h i s best-efficiency point, a l s o called the balance l i n e (see Fig.

lo),

t h e various losses i n the

i m p e l l e r and volute a r e minimum, and t h e pressure d i s t r i b u t i o n i n t h e

volute is nearly uniform.

This uniform d i s t r i b u t i o n gives r i s e t o t h e

minimum net radial force on t h e impeller.

During operation on higher

or lower l i n e s of system f l o w resist"ance (see Fig. lo), the volute pressure d i s t r i b u t i o n becomes nonuniform, and a net radial force i s exerted on t h e impeller t h a t increases as t h e operating condition departs f a r t h e r from t h e balance l i n e .

Thus operation at off-design conditions produces

radial forces on t h e impeller t h a t deflect the overhung s h a f t .

Three incidents of i n s u f f i c i e n t running clearance t o accommodate t h i s deflection

were encountered during operation of the MSRE pumps with molten salt i n the t e s t f a c i l i t y .

During the i n i t i a l molten-salt test ( t e s t 1, Table l),

the prototype pump s h a f t seized i n t h e shield plug.

Operation a t off-

design conditions deflected the shaft s u f f i c i e n t l y t o cause rubbing of t h e hot, dry s h a f t against t h e bore of the s h i e l d plug a t i t s lower end. shaft was friction-welded t o t h e plug over a length of about 4 i n .

radial running clearance between t h e s h a f t and t h e s h i e l d plug w a s

The The

U j

ORNL-LR-DWG 72413R

CONSTANT FLOWRESISTANCE LINES

0 MSRE FUEL CIRCUIT (DESIGN)

a a w

MINIMUM RADIAL FORCE ON IMPELLER PROTOTYPE PUMP OPERATION WITH !3-in. IMPELLER

FLOW 4

Fig. 10. Relationship Between L i n e s of Constant Flow Resistance, Pump Characteristic Curves, and Impeller Radial Load f o r Centrifugal Pumps.

therefore increased from 0.010 t o 0.045 i n . t o avoid s h a f t seizure a t anticipated off-design operating conditions. During t e s t 9, t h e shaft of t h e MSRE f u e l - s a l t pump rubbed against the helium purge labyrinth s e a l .

The rubbing was detected and t h e pump

w a s stopped before seizure could occur. 0.005 i n .

The diametral clearance was

The rubbing evidently occurred as a r e s u l t of t h e buildup

during assembly of e c c e n t r i c i t i e s i n t h e mechanical s t r u c t u r e of the pump, s h a f t deflection due t o dynamic loading, and s h a f t run-out.

The

diametral clearance w a s increased t o 0.010 i n . During t e s t 12, the impeller of the spare reactor f u e l - s a l t pump rubbed against t h e volute.

Rubbing occurred when a flow of cooling air

was s u p p l i e d t o t h e e x t e r i o r of t h e nonwetted portion of t h e pump tank while t h e pump was being operated at 120O0F. It was found t h a t the mounting of t h e volute was s l i g h t l y skewed i n t h e pump tank, and t h e axial running clearance between the volute and the i n l e t shroud of t h e

impeller was l e s s than required.

Additional properly delineated axial

running clearance between the impeller i n l e t shroud and volute was therefore provided. O i l Leakage from the Catch Basin i n t o t h e Pump Tank O i l leakage from t h e catch basin down t h e outside of t h e s h i e l d

plug and i n t o t h e pump tank was observed i n some of the molten-salt pump tests and during i n i t i a l operation of t h e f u e l - s a l t pump with barren salt i n t h e MSRE.

The leakage path traversed a j o i n t t h a t was

sealed with a soft-annealed solid-copper O-ring compressed between adjacent f l a t horizontal surfaces on t h e bearing housing and s h i e l d plug (see Fig. 11). Modifications were made on t h e spare rotary elements f o r t h e f u e l and coolant pumps f o r t h e MSRE. A weld arrangement w a s devised t o s e a l t h e j o i n t between t h e bearing

housing and the s h i e l d plug i n a positive manner.

The relationships be-

tween the pump shaft, t h e shaft lower seal, bearing housing, catch basin, s h i e l d plug, and t h e pump tank are shown i n t h e l a r g e r section i n Fig. 11. !Phe i n s e t s show the portions affected before and a f t e r modification.

The

modification w a s made on both t h e f u e l - and coolant-salt pump spare rotary elements f o r t h e E R E .

ORNL-DWG 66-2049

SOLID COPPER O-RING

BUNA N O-RING LOWER SEAL LOWER SEAL CATCH BASIN

BEFORE MODIFICATION

AFTER MODIFICATION

I SHIELD PLUG

SHAFT

Fig. 11, Cross Sections of Catch Basin Region of Rotary Element Bef o r e and After Modification t o Seal t h e O i l Leak Passage Between Shield Plug and Bearing Housing.

28 Pump !lank Off-Gas Line mugging During test 17 (see Table 1) the purge-gas flow rate down the shaft annulus was set at 4 liters/min to investigate plugging that had been experienced in the fuel-salt pump off-gas line at the MSRE and to test

u I

filters for possible use to prevent the plugging. The purge flow rate on all previous tests was considerably lower (factor of ,10or more). At the high test purge rate some partial plugging in the pump tank offgas line was experienced. The plugging was caused by the solidification of salt aerosol swept out of the pump tank by the purge gas. The aerosol is presumably generated by agitation of the salt in the pump tank by the high-velocity salt jets that issue from the xenon-removal spray ring. The problem was a nuisance but did not interfere with pump operation. Failure of Weld Attachment of Parts of Flow-Straightening Device Test 12 (see !Fable 1) was terminated after the operator reported a strange noise that he had heard only one time. A slight roughening of the trace on the pump power recorder was also observed. Inspection indicated that one of the three parts of a flow-straightening device had become detached and lodged in the impeller inlet. This caused some damage to the inlet edges of the impeller vanes and deformed a swirl preventer of cruciform configuration that was located adjacent to the impeller inlet. Figure 12 shows the posttest configuration of one of the three parts fromthe straightener. Figure 13 shows the rubbing damage to the leading edges of the impeller vanes, and Fig. 14 shows the damage done to the swirl preventer. Figure 15 indicates the locations in the flow straightener from which the three parts were detached. Other than the barely perceptible roughening of the power trace, no effects of the lodged p a r t s on the hydraulic performance of the pump could be detected. The salt flow had carried the detached parts downstream through the venturi meter and the interconnecting salt piping and upward into the impeller inlet. The straightener parts had been welded in intermittent fashion to the carrier pieces, as shown in Fig. 15. The straightener itself was located just upstream of the venturi meter to straighten the salt flow before entry into the meter.

Impeller I n l e t .

i 1

Fig. 13. Rubbing Damage t o I n l e t Edges of Impeller Blades. Damage was caused by rubbing of impeller against detached p a r t of flow straightener t h a t lodged i n impeller i n l e t .

Fig. 14. Damaged Sw enter. Damage was caused by lodging of detached p a r t of flow straightener i n impeller i n l e t .

Fig. 15. Failure of Weld Attachment of Parts in Flow Straightener. Locatibns are shown from which parts were detached.

33 A t t h i s time it was decided t o modify t h e s a l t piping as shown i n

Fig. 16 t o locate t h e venturi meter i n the upper l e g of t h e salt piping and t h e straightener upstream of it near the o u t l e t end of t h e a i r cooler. The designs of t h e straightener and the welds joining i t s p a r t s were a l s o

modified t o reduce the vibration-induced fatigue thought t o be t h e reason f o r t h e detachment of t h e three parts. venter were ,replaced also.

The impeller and the swirl pre-

Mark-2 Fuel-Salt Pump The Mark-2 fuel-salt pump represents a modification t o t h e o r i g i n a l design of the f u e l - s a l t pump t o provide additional volume needed t o accommodate t h e thermal expansion of t h e system f u e l salt. For t h e o r i g i n a l f u e l - s a l t pump, an overflow tank had t o be i n s t a l l e d a t t h e MSFtE t o provide the additional volume, Although t h e Mark-2 pump was fabricated and operated with s a l t i n !

It i s s t i l l being operated i n the t e s t stand, and i n April 1970 had c i r -

i i

t h e molten-salt pump t e s t stand, it was never i n s t a l l e d i n t o t h e MSRE.

culated the salt LiF-BeFs -ZrF4 -ThF4 -UF4 (68.4-24.6-5 .O-1 .1-0.9 mole $) f o r more than 14,000 hr, mainly a t 1200'F.

Its performance has been

s a t i s f a c t o r y i n every respect, except f o r p a r t i a l r e s t r i c t i o n s t o t h e purge-gas flow t h a t occur occasionally i n t h e off-gas l i n e and i n t h e pump s h a f t annulus. Description of Pump The Mark-2 pump has t h e same hydraulic components (impeller and volute), bearing housing, and drive motor designs as those used i n t h e o r i g i n a l f'uel-salt pump. creased by

However, t h e height of t h e pump tank was i n -

9 3/4 i n . t o provide 5 3/4

thermally expanded fuel salt.

f't3 of additional volume f o r t h e

The pump s h a f t i s t h e same, except t h a t

the length of t h e salt-wetted portion was increased a corresponding amount.

The configuration of t h e pump i s shown i n cross section i n

Fig. 17. The detailed designs of i n t e r n a l equipment i n the pump tank (i.e.,

salt splash b a f f l e s and s a l t spray r i n g ) d i f f e r from those provided f o r

W 6

ORNL-DWG 66-2048

RET

INLET PRESSURE

MSRE FREEZE

Fig. 16. Configuration of' Salt Piping in the Molten-Salt Pump Test Stand as Modified After Failure of Weld Attachment of Parts in Flow Straightener.

35 OWL-DWG 69-10459

Fig. 17.

Cross Section of Mark-2 Fuel-Salt' Pump.

36 t h e o r i g i n a l tank (Fig. 1 ) .

The j e t s from t h e spray r i n g do pot impinge

d i r e c t l y i n t o t h e pool of salt i n t h e pump tank but a r e aimed a t t h e inner surface of t h e salt spray b a f f l e .

In addition t h e Mark-2 pump

tank i s equipped with a buoyanq l e v e l indicator (not shown i n Fig. l7),

W 8

which was not used i n the o r i g i n a l pump tank. Hydraulic Performance Eydraulic performance data were obtained a t various pump speeds along a constant l i n e of flow resistance and a t a constant salt temperature of l200OF.

The idata are superimposed i n Fig. 18 on a graph

of water t e s t performance data provided by t h e vendor of t h e impeller and volute.

The head values f r o m t h e molten-salt data a r e within 2 f t

of t h e vendor's values.

Measurement of Undissolved Gas Content i n Circulating S a l t The content of undissolved gas c i r c u l a t i n g i n t h e salt was measured

with the pump operating at t h r e e d i f f e r e n t salt l e v e l s i n t h e pump tank.

A t t h e normal l e v e l and t h e high l e v e l , 5 3/8 i n . above normal, t h e r e w a s no gas detectable i n t h e c i r c u l a t i n g salt by use of t h e r a d i a t i o n densitometer. 0.1 vol

A t t h e l o w l e v e l , 2.4 i n . below normal, a gas content of

was measured.

previous s e c t i o n , )

(The radiation densitometer i s described 5n a

A t t h e normal and high levels, t h e b a f f l e s a r e

evidently e f f e c t i v e i n keeping gas bubbles from being c a r r i e d i n t o t h e circulating salt a t t h e pump inlet. Restrictions t o Purge-Gas Flow During operation of t h e pump, partial r e s t r i c t i o n s have been experienced i n t h e purge-gas flow passages.

Examination after i n i t i a l operation

revealed s o l i d material i n t h e off-gas l i n e as far as 40 ft downstream from t h e pump tank.

It had collected i n valves and other r e s t r i c t e d

flow areas, and therefore it w a s d i f f i c u l t t o maintain the purge-gas flow of 4 liters/min, t h e MSFE design r a t e . therefore i n s t a l l e d approximately

15 ft

A commercial f i l t e r was

downstream from t h e pump tank,

. ORNL-DWG 70-6824

200

400

600

800

1000

1200

1400

4, FLOW (gal)

aulic Performance of Mark-2 Fuel-Salt Pump.

1600 ,

3'8 and there was no f u r t h e r plugging.

A r e s t r i c t i o n now occurs on t h e

average of about once per month i n the pump tank off-gas nozzle or a t

a valve j u s t upstream of t h e f i l t e r .

It i s removed by rapping gn t h e

l i n e or by application of heat with a torch. Examination of a sample of t h e plug material revealed t h a t it was salt in nearly spherical droplet form 15

i n diameter o r l e s s .

The

salt material i s carried as an aerosol i n t h e purge gas from the pump

tank gas space i n t o t h e pump tank off-gas l i n e . There have been eight occasions of partial plugging i n t h e s h a f t annulus ( i n l e t purge-gas passage).

This plugging can be cleared by

e i t h e r stopping t h e pump momentarily and r e s t a r t i n g it o r by heating the system salt t o 1325OF f o r a short period (about 1 h r ) and then r e turning it t o 1200OF. Performance of Molten-Salt Pumps i n MSRE

Two molten-salt pumps, one f o r f u e l salt and one f o r coolant salt, were i n s t a l l e d i n t h e M S a . They were developed with t h e aid of water t e s t s a and t h e salt tests conducted i n t h e molten-salt pump test stand,

as described above.

The two pumps a r e i d e n t i c a l except f o r t h e hydraulic

design (impeller and volute); t h e f u e l pump tank has a spray ring t o provide f o r xenon removal, whereas t h e coolant pump does not; and t h e f u e l pump i s driven at

1175

rpm, while t h e coolant pump i s driven a t

1775 rpm.

Their accumulated operating s t a t i s t i c s , up t o t h e shutdown of the MSRE on December 12, 1969, a r e presented i n Table

4, which gives t h e accumu-

l a t e d pump operating hours f o r c i r c u l a t i o n of molten salt, helium, and t h e combiped hours f o r helium and splt when the system was at gOO째F or above.

The service of t h e MSRE salt pumps, which began i n August 1964,

was satisfactory, and t h e t o t a l operating times f o r t h e pumps exceeded 58,000 hr.

During operation of t h e pumps only one problem was encountered p a r t i a l r e s t r i c t i o n of the off-gas flow.

This problem did not i n t e r -

f e r e with t h e operation of t h e MSRE but was a nuisance i n t h a t it r e quired considerable a t t e n t i o n from time t o time. r e s t r i c t i o n s resulted fromtwo sources:

We believe t h a t the

the freezing of s a l t aerosol

and t h e r a d i o l y t i c polymerization of o i l i n t h e off-gas l i n e s .

Measure-

ments of t h e hydrocarbon content i n the pump off-gas showed 1 t o 2 g/day of hydrocarbons.

The source of salt aerosol i s discussed i n a previous

section, as i s t h e source of t h e o i l .

Partial r e s t r i c t i o n s occurred a t

t h e off-gas o u t l e t nozzles of t h e pump tanks and a t other locations, such as valve s e a t s o r other points of reduced flow area.

I n all other

respects, t h e operation of t h e salt pumps was deemed s a t i s f a c t o r y by t h e

MSFE Operations Group.

Table 4.

Molten-Salt Pump Operation i n MSRE

Process Fluid

-P ~

Fuel

Head Flow (ft) kPm)

Speed Temperature (rpm) (OF)

H e l i u m and molten salt

Molten salt

1200

1175

Helium Coolant

Total Hours

Helium and molten salt Molten s a l t

800

Helium

1175

2900

30,848

1000-1225

21,788

100-1225

7,385

2900

27,438

1000-1275

26,076

100-1275

4,707

A n incident occurred with t h e f u e l - s a l t pump during one s a l t - f i l l i n g

operation i n preparation f o r s t a r t u p of t h e reactor. t o an excessively high leve entering the s h a f t annulus

The salt was forced

the pump tank, which resulted i n salt freezing. Under these circumstances t h e

motor output torque was not s u f f i c i e n t t o t u r n t h e s h a f t .

After appli-

cation of eyCra heat t o t h e pump tank and s u f f i c i e n t time f o r heat t o *

t r a n s f e r i n t o t h e frozen reg

pump was again operative. t h i s incident did not recur.

,t h e

s h a f t became free t o r o t a t e and t h e l l i n g procedures were modified, and

40 Conclusions The developmen, and t e s t program produce

fuel- and coolant-sal,

pumps t h a t , on t h e whole, operated s a t i s f a c t o r i l y and dependably during the operating l i f e of the MSRE from August 1964 t o December 1969.

The

molten-salt hydraulic performance of t h e pumps compared favorably with t h e room-temperature water t e s t performance.

The pump head with molten

salt was observed t o be within 2 f t , or 54, of the water t e s t head, and this difference i s within the accuracy of t h e instrumentation.

The pump s h a f t purge was e f f e c t i v e i n protecting t h e lower s h a f t s e a l region of t h e f u e l - s a l t pump from radioactive f i s s i o n products, and t h e path f o r removal of s e a l o i l leakage remained opened during a l l

MSRE operation.

The o. i l leakage r a t e f o r the lower s h a f t s e a l s was ac-

ceptable (maximum of 30 cc/day) throughout MSRE operation.

A s e a l weld scheme, which joins t h e s h i e l d plug and t h e bearing housing, was developed t o prevent o i l leakage in the lower s e a l catch basin from entering the pump tank.

It was applied t o t h e spare rotary

elements, which were not needed i n the MSRE and therefore were never installed.

Consideration should be given t o t h e handling of salt aerosol i n the design of salt pumps f o r advanced molten-salt reactor systems and t o minimizing t h e production of aerosol.

A device should be provided

t o remove t h e aerosol content i n t h e purge gas and return it t o the salt system.

Acknowledgments The s a t i s f a c t o r y design, development, fabrication, and operation of reactor-grade molten-salt pumps f o r the MSRE required t h e e f f o r t s , enthusiasm, loyalty, and cooperation of more people thab can be named i n t h i s report.

Fâ&#x20AC;&#x2122;rom t h i s Large group, recognition must be given t o

L. V. Wilson f o r h i s e f f o r t s i n t h e design of t h e pumps and t o R. B. Briggs, A. G. Grindell, and R, E. MacFherson f o r t h e s u b s t a n t i a l guidance and encouragement they provided throughout t h e MSRE salt pump development program.

R e f e rences

1. R. B. Briggs, MSRP Semiann. Progr. Rept. July 31, 1964, USAEC Report ORNL-3708, p. 375, Oak Ridge-National Laboratory, 2.

P. G. Smith, Water T e s t Development of t h e Fuel Pump f o r t h e MSRE, USAEC Report ORNL-TM-79, p. 47, O a k Ridge National Laboratory, Mar. 27, 1962.

C. H. Gabbard, Thermal-Stress and Strain-Fatigue Analyses of t h e MSRE Fuel and Coolant Pump Tanks, USAEC Report ORNL-TM-78,p. 71, O a k Ridge National Laboratory, Oct.

3, 1962.

A. G. Grindell, W. F. Boudreau, and H. W. Savage, Development of Centrifugal Plullps f o r Operation with Liquid Metal and Molten S a l t s at 1100-1500째F, Nucl. Sci Eng. , "(1): 8-1 (1960).

R. W. Kelly, G. M. Wood, and H. V, Marman, Development of a HighTemperature Liquid Metal Turbopump, Trans. ASME, Series A, J. of h g . f o r Power, 85(2): 99-107 (1963).

C. Ferguson e t al., Design Summary Report of LCRE Reflector Coolant Pumps and Sump, USAEC Report PWAC-384, p. 41, P r a t t & Whitney A i r craft , Middletown, Connecticut , December 1963. S. Seim and R. A. J a r o s s , 5000 gpm Electromagnetic and Mechanical Pumps f o r EBR-I1 Sodium System, Second Nuclear Engineering and Science Conference sponsored by ASME, Philadelphia, Pa. , March 11-14, 1957.

7. 0.

H. W. Savage, G. D. Whitman, W. G. Cobb, and W. B. McDonald, Components of t h e Fused-Salt and Sodium Circuits of t h e Aircraft Reactor Experiment, USAEC Report OWL-2348, pp. 21-33, Oak Ridge National Laboratory, Feb. 15, 1958.

0. P. S t e e l e 111, High-Temperature Mechanical "Canned Motor" Liquid Met& Pumps, Nuclear Engineering Science Conference sponsored by Engineers J o i n t Council, Chicago, March 17+1, 1958.

10.

R. W. Atz, Performance of " P F Prototype Free-Surface Sodium Pumps, USAEC Report NAA-SR-4336, Atomics International, June 30, 1960.

J. G. C a r r o l l e t al., F i e l d Tests on a Radiation-Resistance Grease, LUbriCatinK fig. , 18(2): 64-70 (1962).

12.

P. G. Smith, Development and Operational Experience with the Lubricat i o n Systems f o r t h e Molten-Salt Reactor Experiment S a l t Pumps, Oak R i d g e National Laboratory, unpublished i n t e r n a l memorandum, June 1970.

R. B. Briggs, MSRP Semimn. Progr. Rept. November 1964, USmC Report 0RNL-3708, pp. 23F235 , Oak Ridge National Laboratory.

14. R. B. Briggs, MSRP Semiann. Progr. Rept. December 31, 1962, USAEC Report ORNL-3369, pp. 123-124, Oak Ridge National Laboratory.

bi *

15. R. B. Briggs, MSRP Semiann. Progr. Rept. January 31, 1963, USAEC Report ORNL-3419, pp. 37-40, Oak RiGe National Laboratory.

43 Appendix MSRE DRAWINGS

Fuel-Salt Pump Drawings BM-8930 F-9830

MSRE Fuel Pump

Assembly

E-10965 0-10964

Flange Weldment

F-9846

Upper Shell Weldment

D-10344

Details

B-9727

Dished Head

D-9711

Volute

D-10068

Bubbler Header Weldment

F-9841

Lower Shell Weldment

D-10561

Sprinkler Head Weldment

D-9849

Thimble Weldment

E-9710

Impeller

D-9839 D-9837 D-9847

Details

Labyrinth Flange Weldment

F-9844

Shield Plug Assembly

E-9843 D-10967 D-9834

Details Motor Guide Weldmest

D-9832

Filler B a r

F-9845

Shaft

D-9838

Shaft Coolant Plug Weldment

Pump Tank Test Assembly

Details

F-9836

ousing Assembly

E-9835 D-9833 D-9831 D-9848

Bearing Housing Welbnent

Modified Flexible Couplipg

D-9850

Modified Oval Ring, ASA ~ 1 6 - 2 0

D-9720

Details

Upper Seal Bearing Clamp Ring

D-10067

Shield P l a t e

D-9840

Details

D-10889

Assembly:

Shaft Leak Tester

D-10888

Assembly:

Leakage Test Fixture

D-10887

Weldment:

Leakage Test Fixture

D-10886

Details

EM-9718 D-9718

Seal, MSRE Pump

D-9721 C-9722

Seal Body Subassembly Seal Body

D-9720

Seal Spring Plate

B-9719

Seal Nose

a-9730

Universal Joint, MSRE Fuel Pump

D-9730 D-9905

Universal J o i n t Assembly

BM-10066 D-10066

Bolt Ektension, MSRF: Fuel Pump

Seal Assembly

Details Bolt Extension Assembly

Coolant -Salt Pump Drawings EM-10062

MSRE Coolant pump

F-10062

Assembly

D-9837 E-10966 D-10964

Details

F-10063

Upper S h e l l Weldment

B-9727

Dished Head

D-10068

Bubbler Header Weldment

D-9771 D-10344 D-10344

Volute

F-10064

Lower Shell

D-10065

Thimble Weldment

D-9770

Impeller Details

D-9834

Pump Tank T e s t Assembly Flange Weldment

Details Details

u f

45 D-9847 D-9849

Labyrinth Flange Weldment

F-9844

Shield Plug Assembly

E-9843 D-10967

Details

Motor Guide Weldment

D-9833 D-9837

Details

D-9832

Filler B a r

F-9845

Shaft

D-9838

Shaft Coolant Plug Weldment

F-9836

Bearing Housing Assembly

E-9835 D-9831 D-9848

Bearing Housing Weldment Modified Flexible Coupling

D-9850

Modified Oval Ring

D-9839

Tachometer Block

D-9720

Details

D-10092

lmpeller Wrench Assembly

BM-9718 D-9718

Seal., MSRE Pump

D-9721

Seal. Body Subassembly

C-9722

Seal Body

D-9720

Details Seal Nose

D-9719

Details

Bearing Clamp Ring

Seal Assembly

Fuel and Coolant Pump Drive-Motor Drawings

u i

653 J 015 653 J 009 828 D 144 472 B 183 319157 ED 18399

General Assembly General Assembly eneral Assembly S t a t o r Lamination Details Wiring Diagram f g r 6 Pole ring Diagram f o r 4 Pole

440 A 811

Terminal

440 A 800

B a l l Bearing Detail

46 472 B 233

Seal

W *

Lubrication Stand Drawings

BM-41801

Lube O i l Package, MSRE

E-41801

Piping Assembly

E-41807 E-41803 E-41802 E-41806

Support Frame Tank Piping Subassembly Tank Assembly

Flange, Double 0-Ring Seal

D-41810

Breather Line

D-41808

Pump Discharge Manifold

D-41812

Details

D- 41813

F i l t e r Modification and Assembly

D-41809

Supply Manifold

D-41811 D-41804 D-41805 D-41814 E-41815

Return Manif old

E-41816 D-55573

Style "SSD" Valve Modification General Notes Process Piping Connections Instrumentation Assembly and Power Connections '

D-55572

Instrument Support Tray Flaw Element (Coolant) Flow Element (Lube)

Mark-2 Fuel-Pump Drawings F-56300

Assembly

F-56301

Test Assembly of Pump Tank

E-9710

Impeller

D-9839 D-9837 D-9847 D-9849

Impeller Nut

Slinger Labyrinth Flange i

Details

F-9844

Shield Plug Assembly

D-10967

Motor Guide

47 D-4b225

Clamp

D-9834

Seal

D-9832

F i l l e r Bar

F-56304

Shaft

D-9838

Shaft Coolant Plug

F-9836

Bearing Housing Assembly

D-9833 0-9831 D-9848

Seal Modified Flexible Coupling

D-9850

Modified Oval Ring

D-9720

Details

D-10067

Shield Plate

D-56307

Spool Piece

D-55508 Ed424

XFMR Mtg, Plate

E- 48423

Splash Baffle Weldment

F- 56302

Upper Shell Weldment

Bearing Clamp Ring

Details

Lower Shell Weldment Volute Level Indicator Det a i l s

- Float Assembly and

c-48935

Lube O i l J e t Pump Assembly and Details

B-9727

36-in. Flanged and Dished Head

D-10964

Weldment Flange

D-56 305

Capsule Guide and Latch Stop

D-56306

Bubbler Hegder Weldment

Q-10344

Details

BM-9718 0-9718

Seal, MSRE MK-2 Fuel Pump Seal Assembly

D-9721

Seal Body Subassembly

C-9722

Seal Body

D-9720

Seal Spring Plate

B-9719

Seal Nose

BM-9730

Universal Joint, MSRE Fuel Pump

D-9730

Universal J o i n t Assembly

D-9905

%tails

m-10066 D-10066

Bolt Extension, MSRE Fuel Pump Bolt Extension

W '1

lpi

ORNL-TM-2987

Internal Distribution

. c

1. R. 2 , S. 3. H. 4. S. 5. M. 6. C. 7. E.

8. 9. 10. 11. 12.

13. 14. 15. 16. 17. 18. I

19. 20. 21. 22.

23.

24. 25.

26. 27. 28.

29. 30.

31. 32.

...

33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47.

F. Apple

J. Ball F. Bauman E. Beall Bender E. Bettis S. Bettis F. F. Blankenship R. Blumberg E. G. Bohlmann C, J. Borkowski R. B. Briggs D. W. Cardwell C. J. Claffey C. W. Collins E. L. Compere W. H. Cook J. W. Cooke W. B. Cottrell J. L. Crowley F. L. Culler J. H. DeVan J. R. Distefano S. J. Ditto F. A. D O S ~ W. P. Eatherly J. R. Engel E. P. Epler A. P. Fraas 3. H. Frye L. C. N l e r C. H. Gabbard R. B. Gallaer W. R. Grimes A. G. Grindell R. H. Guymon P. H. Harley W. 0. Harms P, N. Baubenreich R. E, Helms P. G. Herndon E. C. Hise H. W. Hoff'man P. P. Holz A. Houtzeel T. L. Hudson W. R. Huntley

48. 49 50 51

H. Inouye W. H. Jordan P. R. Kasten T. W. Kerlin

J. J. R. A.

53 54 55 56 57 58 59 60. 61. 62. 63 64. 65 66. 67 68. 69 70 71 72 73 74 75 76. 77 78 79 9

80. 81. 82. 83

84. 85

85.

88.

90 91

;a:

J. Keyes W. Koger B. Korsmeyer I. Krakoviak T. S. Kress J. W. pewson R. B. Lindauer M. I. Lundin R. N. Lyon R. E. MacPherson H. E. McCoy H. C. McCurdy C. K. McGlothlan L. E. McNeese J. R. McWherter H. J. Metz A. S. Meyer A. J. Miller R. I;. Moore A. M. Perry M. Richardson R. C. Robertson M. W, Rosenthal H. C. Savage A. W. Savolainen J. H. Shaffer M. J. Skinner G. M. Slaughter A. N. Smith P. G. Smith I. Spiewak R e D e Stulting D. A. Sundberg E. H. Taylor R e E . Thorn D. B. Trauger A. M. Weinberg J. R. Weir J. C. White G. D. Whitman L. V. Wilson Gale Young H. C. Young

50 Internal Distribution (continued) 7

95-96 97-98 99-102 103

Central Research Library Y-12 Document Reference Section Laboratory Records Department Laboratory Records Department (RC) Ekternal Distribution

104 I

$05

C. E. Anthony, Westinghouse Electro Mechanical Division, Cheswick, Pa. 15024 R. N. Bowman, Bingham-Willamette Company, Portland, Oregon

97200

106. Arthur Bunke, Byron Jackson Pumps, Inc., Los Angeles, Calif. 90000 107. E. J. Cattabiani, Westinghouse Electro Mechanical Division, Cheswick, Pa. 15024 108. D. F. Cope, REF, SSR, AEC, ORNL Charles R. Domeck, USAEC, Washington, D.C. 20000 lW 110. David Elias, USAEC, Washington, D.C. 20000 111. A. Giambusso, USAEC, Washington, D.C. 20000 112. Kermit Laughon, USAEC, OSR, ORNL 113. Liquid Metal Engineering Center, c/o Atomics International, P.O. Box 309, Canoga Park, Calif. 91303 (Attention: R. W. Dickinson) 114 C. L. Matthews, USAEC, OSR, ORNL 115 T. W. McIntosh, USAEC, Washington, D.C. 20000 116 C. E. Miller, Jr., DRDT, USAEC, Washington, D.C. 2oooO 117 M. A. Rosen, D m , USAEC, Washington, D.C. 20000 118 He M. Roth, USAEC, Oak Ridge Operations 20000 119 J. J. Schreiber, DIiDT, USAEC, Washington, D.C. 120 M. Shaw, USAEC, Washington, D.C. 20000 121 W. L. Smalley, USAEC, Oak Ridge Operations 122. Laboratory and University Division, OR0 123-137 Division of Technical Information Extension (DTIE)

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