ORNL-TM-2974 by Jon Morrow

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HELP O A K RIDGE N A T I O N A L LABORATORY operated by

UNION CARBIDE CORPORATION NUCLEAR DIVISION for the

U.S. ATOMIC ENERGY COMMISSION ORNL- TM- 2974 COPY NO.

DATE

- A p r i l 7,

1970

PLANS FOR POST-OPERATION EXAMINATION OF THE MOLTEN-SALT REACTOR EXPERl3ENT P. N. Haubenreich and M. Richardson

ABSTRACT I n December 1969, a f t e r more t h a n 4 succ , f u l y e a r s , t h e n u c l e a r o p e r a t i o n o f t h e MSFE was concluded and t h e p l a n t was p l a c e d i n standby. Work planned f o r e a r l y i n FY-1971 i n c l u d e s removal of some c o r e g r a p h i t e ; viewing i n s i d e t h e r e a c t o r vessel and i n s i d e t h e fuel-pump bowl; i n s p e c t i o n of p o r t i o n s of t h e s a l t piping, t h e o f f g a s c h a r c o a l bed, t h e c o o l a n t s a l t pump, and t h e c o n t r o l r o d s ; and t e s t i n g t h e c o o l a n t s a l t flowmeter. Each s t u d y i s j u s t i f i e d by i t s b e n e f i t t o t h e Molten-Salt Reactor Program. Procedures and t o o l s are available f o r some j o b s ; f o r o t h e r s , t h e y a r e c u r r e n t l y b e i n g developed. 2

Keywords : r e a c t o r s , f u s e d salts, MSRE, o p e r a t i o n , i n s p e c t i o n , maintenance, remote handling, l e a k s .

NOTICE This document contains information of a preliminary nature and was prepared primorily for internol use at the Oak Ridge National Laboratory. It is subiect to revision or correction and t h e r a k e does not represent a final report.

R I

T h i s report was prepared as an account of Government sponsored work.

Neither the United States,

nor the Commission, nor any person acting on bahalf of the Commission:

Makes any warranty

or representation, expressed or implied, w i t h respect to the accuracy.

completeness, or

usefulness of the

any

apparatus,

information,

method,

infmmation contained i n this report, or that the use of or process disclosed

i n t h i s report may not infringe

privately owned rights; or

Assumes any l i a b i l i t i e s w i t h respect to

tha use of, or for damages resulting from the use of

any information, apparatus, method, or process disclosed i n t h i s report. As used i n the above, "person

acting on behalf of the Commission"

includes any employee or

contractor of the Commission, or employes of such contractor, t o the extent that such employee or

contractor of the Commission,

or employee of

such contractor

prepares,

disseminates,

provides access to, any information pursuant t o h i s employment m contract w i t h the Commission,

or h i s employment w i t h such contractor.

iii

. CONTENTS Page

ABSTRACT

.............................

........................... GOALS OF POST OPERATION EXAMINATIONS . . . . . . . . . . . . . . . CRITERIA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . STEPS I N DEFINING THE CAMPAIGN . . . . . . . . . . . . . . . . . . STUDIES AND TASKS TO BE UNDERTAKEN . . . . . . . . . . . . . . . . I n v e s t i g a t i o n of Leak Near Freeze Valve FV-105

5 5 6 6 7 9

Examination of

INTROIXJCTION

Examination of

........ S u r f a c e s I n s i d e t h e Fuel-Pump Bowl . . . . . . Reactor V e s s e l I n t e r n a l s . . . . . . . . . . .

..... I n s p e c t i o n of F u e l D r a i n Line . . . Examination of Charcoal Bed I n l e t . Examination of R a d i a t o r Tubing . .

Examination of F u e l P i p i n g

. . . .

Examination of Thermocouple Wells i n Coolant P i p i n g T e s t o f d/p System on Coolant S a l t Flowmeter I n s p e c t i o n o f Coolant-Pump Rotary Element

.. .. .. .. ..

. . . . .

......

.......... I n s p e c t i o n of C o n t r o l Rods . . . . . . . . . . . . . . . . . . V e r i f i c a t i o n of Remote M a i n t a i n a b i l i t y . . . . . . . . . . . Removal o f C o o l a n t S a l t P u m p B o w l a n d P i p i n g

........

................ Decontamination . . . . . . . . . . . . . . . . . . . . . . . Securing the Plant . . . . . . . . . . . . . . . . . . . . . . Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . JOB DESCRIPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . SCHEDULF: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . STATUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Recovery of MSRE Coolant S a l t

12 12 12

13 13 13 14 14 15 15

1-5 16 17 27 27

INTRODUCTION

The primary purpose of t h e Molten-Salt Reactor Experiment was t o demonstrate t h e p r a c t i c a l i t y o f t h e m o l t e n - s a l t r e a c t o r concept. end i t s design'

To t h i s

i n c o r p o r a t e d e s s e n t i a l l y t h e same m a t e r i a l s and many of

t h e d e s i g n f e a t u r e s of proposed m o l t e n - s a l t power r e a c t o r s .

4 years

purpose w a s accomplished as it was o p e r a t e d f o r more t h a n Ridge N a t i o n a l Laboratory.

I t s primary a t Oak

Experience2 w i t h t h e MSRE w a s q u i t e encouraging

and a g r e a t d e a l of new information ( p a r t i c u l a r l y w i t h r e g a r d t o f i s s i o n I n December

product behavior) w a s obtained.

1969, t h e r e a c t o r w a s s h u t

down because i t s o r i g i n a l g o a l s had been met and continued o p e r a t i o n , a l t h o u g h o f f e r i n g a d d i t i o n a l information, could n o t be j u s t i f i e d i n t h e very s t r i n g e n t budget s i t u a t i o n .

Except f o r removal of an e x p e r i m e n t a l

a r r a y from t h e core, a l l p o s t - o p e r a t i o n examination w a s d e f e r r e d u n t i l t h e next f i s c a l y e a r , condition

I n t h e i n t e r i m t h e r e a c t o r was p l a c e d i n a standby

' GOALS OF POST-OPERATION EXAMINATIONS

The broad g o a l of t h e p o s t - o p e r a t i o n examinations i s t o complete t h e g a t h e r i n g of information from t h e MSRE by i n - p l a c e i n s p e c t i o n , removal o f specimens and some p i e c e s of equipment, and d e t a i l e d examination of t h e s e in hot c e l l s .

S p e c i f i c o b j e c t i v e s i n c l u d e d e t e r m i n a t i o n of t h e c o n d i t i o n

of m a t e r i a l s w i t h t h e g r e a t e s t exposure t o t h e r e a c t o r environment, t h e c o n d i t i o n of key equipment (pumps, h e a t e r s , i n s u l a t i o n ) , t h e l o c a t i o n and n a t u r e of d e p o s i t s i n s e l e c t e d p a r t s of t h e f u e l s a l t and o f f g a s systems,

'R. C . Robertson, MSRE Design and Operations Report, P a r t I D e s c r i p t i o n of R e a c t o r Design, ORNL-TM-728 (January 1965)

2P. N. Haubenreich and J. R . Engel, "Experience w i t h t h e MSRE,!' Nucl. Appl. Tech. 8, 118 (1970)

?P. N. Haubenreich and R. H. Guymon, P l a n s f o r t h e MSRE Between End of Nuclear Operation and Beginning of Post-Operation Examinations,

i n t e r n a l memorandum MSR-69-121 (December

1969)

6 and t h e e x a c t l o c a t i o n and n a t u r e of a l e a k i n a s a l t f r e e z e v a l v e .

This

information w i l l i n f l u e n c e m a t e r i a l s development and t h e d e s i g n of equipment and systems f o r f u t u r e m o l t e n - s a l t r e a c t o r s .

CRITERIA The scope of t h e p o s t - o p e r a t i o n s t u d i e s w i l l b e l i m i t e d t o t h o s e whose c o s t s a r e j u s t i f i e d by t h e b e n e f i t s t o t h e M o l t e n - S a l t Reactor Program. Tentative plans c a l l f o r holding t h e radioactive f u e l s a l t (about 360,000 c u r i e s of f i s s i o n products as of J u l y

1970) f r o z e n

t a n k s u n t i l such time as s a l t mine d i s p o s a l i s f e a s i b l e .

i n t h e MSRE

The p o s t - o p e r a t i o n

examinations s h a l l n o t p r e v e n t t h e u l t i m a t e removal of t h e s a l t nor l e a v e t h e system i n an unsafe c o n d i t i o n i n t h e i n t e r i m .

I n a d d i t i o n , t o pre-

s e r v e t h e o p t i o n of f l u o r i n a t i n g t h e s a l t f o r uranium recovery, t h e operab i l i t y of t h e p r o c e s s i n g f a c i l i t y s h a l l be p r e s e r v e d . Exposure of p e r s o n n e l t o r a d i a t i o n d u r i n g t h e p o s t - o p e r a t i o n examin a t i o n s h a l l n o t exceed normal o c c u p a t i o n a l l i m i t s p r e s c r i b e d by ORNL and t h e USAEC. STEPS IN DEFINING THE CAMPAIGN

Planning f o r t h e p o s t - o p e r a t i o n examination, t o some e x t e n t , began w i t h t h e d e s i g n of t h e r e a c t o r , when p r o v i s i o n s were made f o r removing t h e

5 c e n t r a l b a r s of c o r e g r a p h i t e .

F i n a l s e l e c t i o n of p o s t - o p e r a t i o n s t u d i e s ,

of course, had t o await o p e r a t i n g e x p e r i e n c e and e v a l u a t i o n t o p o i n t o u t a r e a s of most i n t e r e s t and o t h e r program developments ( s u c h as t h e budget) t o determine what could be j u s t i f i e d . I n February

1969, t h e head of t h e MSRE Operations Department s e n t a

r e q u e s t f o r s u g g e s t i o n s f o r f i n a l o p e r a t i o n s and shutdown of t h e MSRE t o group l e a d e r s i n t h e MSRP.

Responses were c o n s o l i d a t e d t o e l i m i n a t e d u p l i -

1969, a t e n t a t i v e l i s t of p o s t - o p e r a t i o n t a s k s w a s d i s t r i b u t e d with a r e q u e s t f o r comrr.ents. This l i s t was d i s c u s s e d w i t h ORNL

c a t i o n s and i n October

and AEC-OR0 r e a c t o r s a f e t y review committees and w i t h AEC-DRDT r e p r e s e n t a tives.

A f t e r d i s c u s s i o n and review of t h e t e n t a t i v e l i s t w i t h MSRP s t a f f

7 members i n which b e n e f i t s were weighed a g a i n s t c o s t s , t h e program d e s c r i b e d i n t h e n e x t s e c t i o n w a s a r r i v e d a t i n March

1970.

SWDIES AND TASKS TO BE UNDERTAKEN The s t u d i e s t h a t we propose t o make a r e l i s t e d i n Table 1. Under each s t u d y a r e l i s t e d t h e s e p a r a t e j o b s , some t o b e done o n - s i t e ,

X-10 h o t c e l l s , involved i n t h a t s t u d y .

some i n

Not shown i n t h e t a b l e a r e t h e

t a s k s o f removing some items f o r u s e i n development f a c i l i t i e s , decontamin a t i n g a r e a s o u t s i d e t h e containment c e l l s , s e c u r i n g t h e p l a n t , and d i s posing of t h e f u e l s a l t .

The j u s t i f i c a t i o n f o r and o b j e c t i v e s of each

s t u d y ( i n t h e o r d e r l i s t e d i n Table 1) and each t a s k are d i s c u s s e d i n t h e t e x t of t h i s s e c t i o n ,

Job descriptions,

i n c l u d i n g purposes and g e n e r a l

procedures, a r e p r e s e n t e d i n t h e n e x t s e c t i o n .

Table 1

L i s t of S t u d i e s t o be Made and t h e Jobs t h a t w i l l be Involved I n v e s t i g a t i o n of l e a k n e a r f r e e z e v a l v e FV-105 View v i c i n i t y of Fv-105 E x c i s e Fv-105 I n s p e c t FV- lo5 Examination of fuel-pump bowl i n t e r n a l s E x c i s e sampler cage and b a f f l e View i n s i d e of pump bowl I n s p e c t sampler cage and b a f f l e Examination of r e a c t o r v e s s e l i n t e r n a l s P r e p a r e f o r c o r e work Remove a c c e s s p l u g and r o d thimbles Remove some c o r e g r a p h i t e V i e w c o r e and i n s i d e of r e a c t o r v e s s e l heads Close r e a c t o r a c c e s s Cut o f f p i e c e of rod thimble Inspect core graphite b a r I n s p e c t rod thimble p i e c e

8 Table 1 ( c o n t i n u e d ) Examination of f u e l p i p i n g Excise s e c t i o n s of p i p i n g a t h e a t exchanger i n l e t and o u t l e t I n s p e c t s e c t i o n s of p i p i n g I n s p e c t i o n of f u e l d r a i n l i n e Remove h e a t e r H-103 View d r a i n l i n e i n s i d e r e a c t o r f u r n a c e Examination of c h a r c o a l bed i n l e t Excise i n l e t s e c t i o n of Inspect i n l e t section

main c h a r c o a l bed

Examination of r a d i a t o r t u b i n g Excise t u b i n g n e a r i n l e t and n e a r o u t l e t I n s p e c t f o r d e p o s i t s and c o r r o s i o n Examination of thermocouple w e l l s i n c o o l a n t s a l t p i p i n g Excise w e l l s a t r a d i a t o r i n l e t and o u t l e t I n s p e c t f o r d e p o s i t s and i n t e g r i t y T e s t of d i f f e r e n t i a l p r e s s u r e system on c o o l a n t s a l t flowmeter Cut c o o l a n t p i p i n g T e s t p r e s s u r e measuring system I n s p e c t i o n of c o o l a n t pump r o t a r y element Remove r o t a r y element Inspect I n s p e c t i o n of c o n t r o l r o d s Examine Remove elements I n s p e c t elements V e r i f i c a t i o n of remote m a i n t a i n a b i l i t y Remove and i n s p e c t h e a t e r u n i t s Remove f u e l pump motor Disconnect f u e l sampler l i n e

9 v

I n v e s t i g a t i o n of Leak Near Freeze Valve FV-lo5 A l e a k appeared i n t h e primary system on December 12, a f t e r t h e scheduled end of n u c l e a r o p e r a t i o n .

1969

shortly

C o r r e l a t i o n of changes i n

c e l l a i r a c t i v i t i e s w i t h c e r t a i n o p e r a t i o n s i n d i c a t e d t h a t a small l e a k had developed i n or n e a r f r e e z e v a l v e

FV-lo5 ( l e a d i n g t o f u e l d r a i n t a n k

FD-2) a b o u t two hours a f t e r t h e f u e l was d r a i n e d f o r t h e l a s t t i m e . Amounts of xenon and i o d i n e i n d i c a t e d t h a t a few f t 3 of gas and perhaps some

s a l t (1 cc or l e s s ) escaped i n t o t h e c e l l b e f o r e t h e l e a k was e f f e c t i v e l y stopped by f r e e z i n g s a l t i n t h e l i n e . T h i s i s t h e only l e a k t h a t e v e r o c c u r r e d i n t h e primary system and t h e e x p l a n a t i o n i s n o t known.

Examination of r a d i o g r a p h s and o t h e r con-

s t r u c t i o n r e c o r d s showed n o t h i n g s u s p i c i o u s .

We b e l i e v e c o r r o s i o n could

n o t have been a s i g n i f i c a n t f a c t o r i n t h e o r i g i n of t h e l e a k , and r a d i a t i o n damage a t t h i s l o c a t i o n should be v i r t u a l l y n i l .

The most l i k e l y h y p o t h e s i s

i s t h a t t h e r m a l s t r e s s e s i n t h e v a l v e caused a c r a c k t o o r i g i n a t e a t t h e

welded j u n c t u r e of t h e c o o l i n g - a i r shroud and t h e p i p e and t o propagate through t h e p i p e w a l l . We should determine t h e e x a c t l o c a t i o n and d e s c r i p t i o n of t h e l e a k and, i f p o s s i b l e , d e r i v e an e x p l a n a t i o n . Examination of S u r f a c e s I n s i d e t h e Fuel-Pump Bowl During o p e r a t i o n of t h e MSRE, e f f e c t s r e l a t e d t o t h e s a l t - g a s i n t e r f a c e i n t h e fuel-pump bowl were of c o n s i d e r a b l e importance.

Bubbler l e v e l

elements i n d i c a t e d t h a t c o n s i d e r a b l e amounts of gas were c a r r i e d under t h e s a l t s u r f a c e by t h e xenon s t r i p p e r j e t s ,

The d e n s i t y p r o f i l e above t h e

b u b b l e r s could n o t be measured, b u t t h e f l u i d s u r f a c e w a s c e r t a i n l y h i g h e r because of t h e g a s ,

There i s reason t o t h i n k t h a t t h e s u r f a c e w a s n o t

q u i t e uniform ( b e i n g lower i n s i d e t h e sampler b a f f l e , f o r example).

Certain

f i s s i o n products tended t o c o n c e n t r a t e a t s a l t s u r f a c e s , w i t h perhaps some going i n t o t h e gas space as a "smoke."

O i l l e a k e d i n t o t h e pump bowl from

t h e s h a f t b e a r i n g r e g i o n a t a few c c p e r day,

Some o i l decomposition pro-

d u c t s probably d e p o s i t e d on t h e pump bowl s u r f a c e s and some on t h e s a l t where t h e y may have i n f l u e n c e d f i s s i o n p r o d u c t s e p a r a t i o n and bubble behavior. Y

Thermocouple r e a d i n g s i n d i c a t e d t h a t f i s s i o n product h e a t i n g of

t h e pump bowl above t h e s a l t l e v e l was moderate b u t changed from time t o time f o r unknown r e a s o n s . A sample c a p s u l e w a s dropped i n t o t h e pump bowl i n August a n o t h e r i n March i n May

1967 and

1968. The s t e e l cap of t h e f i r s t c a p s u l e was r e t r i e v e d

1968. There w a s some evidence t h a t t h e second c a p s u l e w a s jammed

between t h e cage and b a f f l e d u r i n g recovery a t t e m p t s . We should observe s u r f a c e s i n s i d e t h e pump bowl f o r evidence of depos i t i o n and t h e p a t t e r n s d i s p l a y e d .

It a p p e a r s now t h a t it w i l l probably

be p r a c t i c a l t o c u t o u t a s e c t i o n o f t h e pump bowl t o p w i t h t h e sample cage and b a f f l e a t t a c h e d .

T h i s would make it p o s s i b l e t o determine much

more about t h e d e p o s i t s and a l s o t o i n s p e c t f o r evidence o f c o r r o s i o n , (Conditions i n t h e v i c i n i t y of t h e d i s s i m i l a r m e t a l j u n c t i o n s i n t h e sample capsule a r e p a r t i c u l a r l y i n t e r e s t i n g . )

The i n f o r m a t i o n w i l l a i d i n under-

s t a n d i n g t h e MSRE b e h a v i o r and w i l l be u s e f u l i n e v a l u a t i n g d e s i g n of o f f gas systems f o r f u t u r e m o l t e n - s a l t r e a c t o r s . Examination of Reactor V e s s e l I n t e r n a l s The e f f e c t of r e a c t o r o p e r a t i o n on c o r e m a t e r i a l s w a s monitored by exposure a t t h e c e n t e r of t h e c o r e of e x p e r i m e n t a l a r r a y s c o n t a i n i n g s p e c i mens of g r a p h i t e and Hastelloy-N l i k e t h o s e used i n t h e c o n s t r u c t i o n of t h e M5RF:.

Arrays were removed a f t e r 1087,

e q u i v a l e n t f u l l - p o w e r hours.

4510, 9005, 11,555, and 13,172

U s u a l l y t h e replacement a r r a y i n c l u d e d some

subassemblies w i t h p r e v i o u s exposure, s o very long t o t a l exposures were accumulated on some specimens b e f o r e d e t a i l e d examination and t e s t i n g . The c o n d i t i o n s of t h e specimens, which were assumed t o b e t y p i c a l of t h e c o r e , never gave any cause f o r concern over t h e c o n d i t i o n of t h e c o r e . Although t h i s s u r v e i l l a n c e program was presumably q u i t e adequate, i t s v a l i d i t y can b e supported by examination of p o r t i o n s of t h e c o r e g r a p h i t e and Hastelloy-N exposed from s t a r t t o end of t h e MSRE o p e r a t i o n . The c o n d i t i o n of Hastelloy-N can be determined by i n s p e c t i o n of t h e removable c o r e a c c e s s assembly, which l n c l u d e s t h e c o n t r o l rod t h i m b l e s and a p l u g exposed t o t h e f u e l stream i n t h e c o r e e x i t .

A f t e r t h e assembly

has been v i s u a l l y i n s p e c t e d i n t h e r e a c t o r c e l l , a p o r t i o n o f a r o d thimble can be c u t o f f and examined c l o s e l y i n a h o t c e l l .

Metallographic

examination of i n t e r i o r s u r f a c e s w i l l r e v e a l any e f f e c t of t h e exposure t o t h e c e l l atmosphere used f o r c o o l i n g .

The e x t e r i o r s u r f a c e w i l l show

e f f e c t s of very l o n g exposure t o t h e f u e l s a l t .

( I t w i l l n o t be p r a c t i c a l

t o shape specimens f o r p h y s i c a l p r o p e r t y t e s t i n g from t h e thimbles, b u t t h i s i s unnecessary s i n c e i r r a d i a t i o n e f f e c t s were w e l l d e s c r i b e d by t h e specimens from t h e e x p e r i m e n t a l a r r a y s .) Removal of one of t h e f i v e c e n t r a l s t r i n g e r s w i l l make a v a i l a b l e g r a p h i t e exposed t o f u e l flowing through channels w i t h a c r o s s s e c t i o n t y p i c a l of t h e b u l k of t h e c o r e .

S u r f a c e appearance and p e n e t r a t i o n of

s a l t c o n s t i t u e n t s and f i s s i o n products i n r e g i o n s f r e e of flaws should be

compared w i t h r e s u l t s from t h e e x p e r i m e n t a l a r r a y s . There was no d e t e c t a b l e evidence of any p h y s i c a l damage t o t h e c o r e d u r i n g o p e r a t i o n , nor d i d thermocouple r e a d i n g s on t h e lower head and n e a r t h e c o r e s u p p o r t f l a n g e i n d i c a t e any s u b s t a n t i a l accumulation of sediment. Nevertheless, a look w i l l be worthwhile.

An o p t i c a l device and l i g h t can

b e used t o view and photograph t h e t o p of t h e c o r e and t h e upper head of t h e r e a c t o r v e s s e l , t h e lower g r i d s t r u c t u r e , t h e bottom head, and t h e drain l i n e inlet.

If l o o s e fragments, broken g r a p h i t e , sediment or o t h e r

d e p o s i t s a r e discovered, t h e y should be examined as c l o s e l y as i s p r a c t i c a l . Examination of F u e l P i p i n g The MSRE: o p e r a t e d f o r 13,172 e q u i v a l e n t f u l l - p o w e r hours w i t h a temperature d i f f e r e n c e of 40째F between t h e f u e l e n t e r i n g and l e a v i n g t h e h e a t exchanger.

Close examination and comparison of Hastelloy-N s u r f a c e s

exposed t o f u e l a t t h e extremes of t h e temperature range w i l l p r o v i d e i n f o r m a t i o n on c o r r o s i o n and mass t r a n s p o r t under t h e r e a c t o r c o n d i t i o n s . S h o r t s e c t i o n s of t h e 5-inch p i p e n e a r t h e h e a t exchanger i n l e t and between t h e h e a t exchanger and t h e r e a c t o r v e s s e l should be c u t o u t and examined m e t a l l o g r a p h i c a l l y f o r t h i s purpose. I n s p e c t i o n of Fuel Drain Line The j u n c t u r e of t h e f u e l d r a i n l i n e w i t h t h e r e a c t o r v e s s e l was subj e c t e d t o a combination of s t r e s s and i r r a d i a t i o n a b o u t as s e v e r e as any in the reactor.

Removal of t h i s s e c t i o n i s n o t p r a c t i c a l , b u t it can b e

viewed from a d i s t a n c e by removal of h e a t e r H-103 and i n s e r t i o n of viewing

12 W

devices i n i t s place i m i d e the r e a c t o r furnace.

The j u n c t u r e , t h e d r a i n

l i n e , and t h e e x t e r i o r of t h e i n s u l a t i o n box around t h e d r a i n v a l v e should

be s c r u t i n i z e d f o r any evidence of i n c i p i e n t t r o u b l e . Examination of Charcoal Bed I n l e t During t h e i n i t i a l e s c a l a t i o n of t h e MSRE power i n

1966, plugging

occurred a t s e v e r a l p o i n t s i n t h e f u e l o f f g a s system, i n c l u d i n g t h e i n l e t s of t h e c h a r c o a l b e d s .

Even a f t e r t h e i n s t a l l a t i o n of a n e f f i c i e n t f i l t e r

( t h e " p a r t i c l e t r a p " ) , plugging r e c u r r e d a t t h e c h a r c o a l bed i n l e t s .

This

w a s b e l i e v e d t o be due t o polymerization of o i l vapors downstream of t h e

f i l t e r and accumulation of t h e polymers on t h e s t e e l wool i n t h e e n t r a n c e s of t h e beds.

T h i s could n o t b e v e r i f i e d d i r e c t l y , b u t t h e r e s t r i c t i o n s

could be c l e a r e d t e m p o r a r i l y by lowering t h e c o o l i n g water l e v e l around t h e beds and a p p l y i n g h e a t t o t h e i n l e t s e c t i o n .

There w a s concern over

p o s s i b l e r e d u c t i o n of t h e a d s o r p t i v e c a p a c i t y of t h e c h a r c o a l by t h e o i l r e s i d u e s b u t no change was d e t e c t a b l e from t h e f e w thermocouples spaced a t

80-ft i n t e r v a l s i n t h e bed.

A s h o r t s e c t i o n of t h e i n l e t t o one s e c t i o n

of t h e beds should be c u t o u t and t h e e x p l a n a t i o n f o r t h e r e c u r r e n t plugging verified.

A sample of c h a r c o a l from t h e i n l e t should be t e s t e d and i f i t s

a d s o r p t i v e c a p a c i t y i s s e r i o u s l y reduced, samples should be o b t a i n e d from f u r t h e r a l o n g t h e bed t o determine t h e e x t e n t of t h e e f f e c t . Examination of R a d i a t o r Tubing The chromium c o n c e n t r a t i o n of t h e c o o l a n t s a l t remained v e r y low through t h e e n t i r e o p e r a t i o n , i n d i c a t i n g t h a t c o r r o s i o n w a s extremely low o r t h a t c o r r o s i o n - p r o d u c t chromium w a s b e i n g d e p o s i t e d .

There were no

c o r r o s i o n s u r v e i l l a n c e specimens i n t h e c o o l a n t system.

S e c t i o n s of t h e

3/b-inch t u b i n g should be c u t from t h e r a d i a t o r n e a r t h e i n l e t and o u t l e t ends and examined f o r information on c o r r o s i o n i n t h e c o o l a n t system. Examination of Thermocouple Wells i n Coolant P i p i n g Because of t h e d e s i r e t o e l i m i n a t e , i n s o f a r as p o s s i b l e , c o n c e i v a b l e s o u r c e s of t r o u b l e , t h e MSRE d e s i g n included only 2 thermocouple w e l l s i n s a l t piping:

one each st t h e i n l e t and o u t l e t of t h e r a d i a t o r .

The p i p e

w i t h t h e s e w e l l s should be c u t o u t and s e c t i o n e d and a c a r e f u l i n s p e c t i o n

made t o s e e if t h e w e l l s s u f f e r e d any unusual c o r r o s i o n .

The p o s s i b i l i t y

of d e p o s i t i o n on what were t o some e x t e n t "cold f i n g e r s " should a l s o be *

inve s t i g a t e d

T e s t of d/p System on Coolant S a l t Flowmeter There i s a s i g n i f i c a n t discrepancy between t h e r e a c t o r power t h a t was i n d i c a t e d by t h e system h e a t b a l a n c e and t h e power i n d i c a t e d by observed changes i n i s o t o p i c r a t i o s of uranium and plutonium i n t h e f u e l .

The The

l a t t e r i n d i c a t e d up t o 10 p e r c e n t lower power t h a n t h e h e a t b a l a n c e .

p o s s i b l e r e a s o n s f o r t h e discrepancy have been checked one by one u n t i l now only t h e c o o l a n t s a l t flow r a t e has n o t been v e r i f i e d as thoroughly as possible.

T h i s must b e done.

The u l t i m a t e t e s t w i l l c o n s i s t of c u t t i n g

t h e s a l t l i n e s n e a r t h e v e n t u r i flowmeter and a p p l y i n g s i g n a l s t o t e s t t h e e n t i r e t r a n s m i t t i n g and modifying system. I n s p e c t i o n of Coolant-Pump Rotary Element The s a l t pumps are key components i n a m o l t e n - s a l t r e a c t o r . f o r t h e small amount of o i l leakage ( a b o u t 2

- 5

Except

cc/day) i n t o t h e pump

bowls, t h e r e was no problem with e i t h e r t h e c o o l a n t - s a l t or f u e l - s a l t pump i n t h e MSRE.

The problems due t o o i l leakage were n o t s e r i o u s enough

t o w a r r a n t r e p l a c i n g t h e o r i g i n a l u n i t s with seal-welded replacement r o t a r y elements t h a t would have had no o i l leakage i n t o t h e bowl.

As a result,

t h e o r i g i n a l u n i t s s e r v e d for t h e e n t i r e d u r a t i o n of t h e o p e r a t i o n .

i n s p e c t i o n should be made t o determine the c o n d i t i o n of t h e pumps and t o p e r m i t some judgement as t o remaining s e r v i c e l i f e .

The f u e l and c o o l a n t

r o t a r y elements are e s s e n t i a l l y t h e same, b u t t h e c o o l a n t pump o p e r a t e d c o n s i d e r a b l y longer, pumping s a l t f o r 26,076 h r compared t o 21,788 h r f o r t h e f u e l pump,

S i n c e t h e c o o l a n t pump r o t a r y element i s a l s o nonradio-

a c t i v e and more a c c e s s i b l e , it should be removed and thoroughly i n s p e c t e d . I n s p e c t i o n of C o n t r o l Rods The c o n t r o l r o d s i n t h e MSRE, of a unique, f l e x i b l e design, on t h e

whole performed w e l l ,

There were g r a d u a l changes i n drop times, however,

t h a t were a t t r i b u t e d i n p a r t t o changes i n t h e f l e x i b i l i t y of t h e rods w i t h long exposure and u s e , W

On occasion, rods were p u l l e d o u t of t h e

14 v

thimbles and viewed from a d i s t a n c e i n t h e r e a c t o r c e l l f o r evidence of unusual s c r a t c h e s o r dragging.

(None w a s found.)

It w a s n o t p o s s i b l e t o

i n s p e c t t h e i n t e r n a l s of t h e rod o r t o a s c r i b e a r e a s o n f o r changes i n flexibility. The r o d s must b e p u l l e d t o g a i n a c c e s s t o t h e c o r e and a t t h a t time t h e a c t i v e s e c t i o n of one should be removed f o r examination i n a h o t c e l l . The Inconel-canned A1g3-Gd03 ceramic poison elements should be checked f o r dimensional changes and t h e f l e x i b l e m e t a l hose and rod should b e c l o s e l y inspected. V e r i f i c a t i o n of Remote M a i n t a i n a b i l i t y An important g o a l of t h e MSRE was t o demonstrate t h a t maintenance of t h e molten-salt reactor, with i t s highly radioactive f u e l c i r c u l a t i o n system, w a s i n f a c t p r a c t i c a l .

To t h i s end, t h e r a d i o a c t i v e p o r t i o n s , i n -

c l u d i n g v i r t u a l l y e v e r y t h i n g i n t h e r e a c t o r c e l l , were designed t o b e replaceable.

Replacement of c o r e specimens, work on t h e o f f g a s system,

replacement of a i r - l i n e d i s c o n n e c t s , and r e p a i r of t h e f u e l samplere n r i c h e r and i n - c e l l h e a t e r u n i t s demonstrated t h e f e a s i b i l i t y of t h e g e n e r a l approach.

Some f e a t u r e s were n o t t e s t e d , however, because most

of t h e equipment r e q u i r e d no maintenance. c e r t a i n of t h e s e f e a t u r e s .

It would be worthwhile t o t r y

The d i f f i c u l t y of r e p l a c i n g t h e fuel-pump

motor should be determined by removing t h e o l d motor o r a t l e a s t l o o s e n i n g s e v e r a l of t h e f l a n g e b o l t s ,

The f l a n g e d s e c t i o n of t h e sampler tube,

which w a s designed t o be swung o u t of t h e way f o r pump bowl replacement should be removed as i n t e n d e d .

( T h i s needs t o be done i n p r e p a r a t i o n f o r

c u t t i n g i n t o t h e pump bowl.) Removal of Coolant S a l t Pump Bowl and P i p i n g

It has been proposed t h a t a f l u o r o b o r a t e technology t e s t l o o p be cons t r u c t e d , u s i n g t h e MSRE c o o l a n t pump and o t h e r p o r t i o n s of t h e c o o l a n t

s a l t system,

Since portions outside the reactor c e l l a r e not radioactive,

removal would be a s t r a i g h t f o r w a r d t a s k t h a t can b e done when needed.

The

only c o n s i d e r a t i o n i s t h a t l i n e s l e a d i n g i n t o t h e r e a c t o r c e l l be s e a l e d , s i n c e t h e y a r e p e n e t r a t i o n s of t h e containment envelope.

Recovery of MSRE Coolant S a l t S a l t f o r a proposed l o o p t o t e s t gas i n j e c t i o n and s t r i p p i n g t e c h -

nology can be p r e p a r e d most economically by adding ThF4 and LiF t o t h e MSRE c o o l a n t s a l t .

The c o o l a n t s a l t , 2610 kg of LiF-BeF2

(66 - 34 mole

p e r c e n t ) , should be melted and removed when r e q u i r e d f o r t h i s purpose. T h i s o p e r a t i o n w i l l a l s o t e s t some a s p e c t s of t e c h n i q u e s t h a t may be used e v e n t u a l l y i n d i s p o s a l of t h e f u e l s a l t . Decontamination The s p r e a d of r a d i o a c t i v i t y d u r i n g t h e work d e s c r i b e d above w i l l be c o n t r o l l e d by p r o p e r v e n t i l a t i o n , temporary containment e n c l o s u r e s , t h e e s t a b l i s h m e n t of contamination zones, and o t h e r t e c h n i q u e s t h a t have been proved i n u s e a t t h e MSRE and elsewhere i n ORNL.

When n e c e s s a r y d u r i n g

t h e campaign and a t i t s conclusion, some of t h e contaminated t o o l s and m a t e r i a l w i l l be disposed of and t h e r e s t w i l l be decontaminated.

Before

t h e t a s k i s f i n i s h e d , e v e r y t h i n g o u t s i d e t h e containment w i l l be decontaminated t o s a f e l e v e l s . Securing t h e P l a n t There i s c u r r e n t l y no demand f o r t h e f i s s i l e m a t e r i a l i n t h e E R E f u e l s a l t (37 kg U, 84% 23â&#x20AC;&#x2122;tr). Because of t h e extremely h i g h (220 ppm) and consequent r a d i a t i o n problems,

23%

content

it i s d o u b t f u l t h a t t h e

uranium w i l l e v e r be worth t h e c o s t of r e c o v e r y from t h e s a l t .

We propose

t o keep t h e f u e l s a l t f r o z e n i n t h e MSRE d r a i n t a n k s , s a f e l y c o n t a i n e d u n t i l developments make it p o s s i b l e t o d e c i d e on t h e optimum method of disposal.

Meanwhile t h e o p t i o n of s t r i p p i n g t h e uranium by t h e f l u o r i d e

v o l a t i l i t y p r o c e s s w i l l be r e t a i n e d by p r e s e r v i n g t h e MSRE p r o c e s s i n g plant. The MSRE r e a c t o r c e l l and d r a i n t a n k c e l l w i l l be r e s e a l e d a f t e r t h e examination work i s completed,

S e r v i c e l i n e s i n t o t h e c e l l s which were

l e f t connected t o t h e a n c i l l a r y systems d u r i n g t h e i n t e r i m p e r i o d w i l l be capped t o minimize chances of a c c i d e n t a l openings.

The r e a c t o r equipment

t h a t i s h e a v i l y contaminated with f i s s i o n p r o d u c t s w i l l be r e t a i n e d w i t h i n t h e c e l l s and t h e o f f g a s containment system. Y

( A s of J u l y

1970, t h e

total

16 f i s s i o n p r o d u c t a c t i v i t y i n t h e s a l t and elsewhere i n t h e r e a c t o r w i l l

amount t o a b o u t 360,000 c u r i e s . )

Some r a d i o a c t i v e items w i t h l i t t l e or

no t r a n s f e r a b l e a c t i v i t y may b e p l a c e d i n o t h e r s h i e l d e d c e l l s i n t h e r e a c t o r building.

R a d i a t i o n zones w i l l be d e f i n e d , marked and s e c u r e d as

r e q u i r e d by ORNL procedures.

The c o n d i t i o n s i n t h e r e a c t o r , c e l l s , and

b u i l d i n g w i l l c o n t i n u e t o be monitored remotely by t h e C e n t r a l Waste Monit o r i n g Group a t ORNL.

Access t o t h e r e a c t o r b u i l d i n g and grounds w i l l b e

s t r i c t l y c o n t r o l l e d by t h e e x i s t i n g system of f e n c e s , g a t e s , and guard service. Disposal Items t h a t a r e n o t r e q u i r e d f o r t h e containment of t h e r a d i o a c t i v i t y nor f o r t h e p o s s i b l e f u t u r e o p e r a t i o n of t h e p r o c e s s i n g f a c i l i t y w i l l be i d e n t i f i e d and a d v e r t i s e d .

Those items whose removal can b e j u s t i f i e d by

program needs w i l l be removed.

Such removal w i l l be planned and super-

v i s e d t o guard a g a i n s t i n a d v e r t e n t compromise of t h e c o n t i n u i n g needs of t h e K3RE. The s a f e t y of t h e p l a n t w i l l be reviewed p e r i o d i c a l l y by a p p r o p r i a t e groups i n ORNL. We e x p e c t t h a t e v e n t u a l l y it may become d e s i r a b l e t o t r a n s f e r t h e f u e l s a l t , c o n t a i n i n g t h e f i s s i l e m a t e r i a l and t h e b u l k of t h e f i s s i o n products, t o a more permanent waste s t o r a g e s i t u a t i o n .

The b e s t way t o

g e t t h e s a l t o u t would now a p p e a r t o b e t o c u t the l i n e from t h e s a l t f l u o r i n a t i o n t a n k t o t h e e x p e r i m e n t a l s a l t s t i l l and t r a n s f e r b a t c h e s o f molten s a l t i n t o t r a n s p o r t c o n t a i n e r s connected a t t h a t p o i n t .

It would

a l s o b e f e a s i b l e t o p u l l s a l t i n t o c o n t a i n e r s through a d i p t u b e i n s t a l l e d through t h e d r a i n t a n k a c c e s s p o r t .

A f t e r t h e b u l k of t h e a c t i v i t y i s r e -

moved t h i s way, i f t h e r e i s no f o r e s e e a b l e need f o r equipment i n t h e r e a c t o r and d r a i n c e l l s , t h e c e l l s can be f i l l e d i n and c l o s e d t o provide permanent containment f o r t h e remaining a c t i v i t y .

JOB DESCRIPTIONS T h i s s e c t i o n g i v e s some a d d i t i o n a l d e t a i l on t h e j o b s t h a t w i l l be involved i n t h e s t u d i e s d e s c r i b e d i n t h e p r e v i o u s s e c t i o n .

The l e t t e r s

i n each j o b i d e n t i f i c a t i o n r e f e r t o t h e p r i n c i p a l l o c a t i o n of t h e work (RC = r e a c t o r c e l l ; EC = d r a i n c e l l ; CC = c o o l a n t c e l l ; HC = h o t c e l l a t X-10;

0 = a t r e a c t o r s i t e o u t s i d e of c e l l s ; L = l a b o r a t o r y ) .

The numbers

i n t h e j o b i d e n t i f i c a t i o n r e f e r t o t h e sequence i n which t h e work w i l l probably be done ( s e e Table 2 ) .

The o r d e r i n which t h e j o b s a r e d i s c u s s e d ,

however, i s t h a t i n which t h e y are l i s t e d i n Table 1. The "purpose" i s t h e s p e c i f i c c o n t r i b u t i o n toward t h e b r o a d e r o b j e c t i v e of t h e s t u d y of which t h e j o b i s p a r t .

A p r e l i m i n a r y d e s c r i p t i o n of t h e procedure i s

given t o i n d i c a t e t h e scope of t h e j o b and t h e p r e s e n t p l a n of a t t a c k . The d e t a i l e d procedures have y e t t o be developed and proved i n most c a s e s .

View V i c i n i t y of Freeze Valve FV-105 ( J o b DC-1) Purpose

- To

l o o k f o r evidence of t h e l e a k and i t s c a u s e .

If any

i s found, t o decide more p r e c i s e l y t h e probable l o c a t i o n of t h e l e a k .

any s a l t i s observed, t o determine t h e amount and i t s c o n d i t i o n .

To ob-

t a i n measurements and photographs t o b e used i n d e t a i l e d p l a n s f o r e x c i s i o n of s e c t i o n w i t h t h e l e a k . General Procedure

- Remove

d r a i n c e l l t o p blocks, c u t membrane, s e t

u p maintenance s h i e l d , remove lower blocks, i n s e r t l i g h t s and viewing d e v i c e s , t a k e photographs, remove h e a t e r u n i t s i n v i c i n i t y of FV-105, view and photograph, remove t o o l s , r e i n s t a l l blocks, remove maintenance s h i e l d .

--E x c i s e FV-105 ( J o b DC-2) Purpose

- To

remove t h e s e c t i o n of d r a i n l i n e where t h e l e a k has

been found ( o r i s b e l i e v e d t o be) s o t h a t d e t a i l e d i n s p e c t i o n can b e made, General Procedure

- Set

up maintenance s h i e l d , remove lower block,

i n s t a l l l i g h t s and viewing d e v i c e s .

C l e a r away i n t e r f e r i n g wiring,

18 1

i n s u l a t i o n and s u p p o r t s .

Use p i p e c u t t e r t o s e v e r l i n e s .

L i f t sections

t o be i n s p e c t e d i n t o s h i e l d e d c a r r i e r and t r a n s p o r t t o h o t c e l l . ends of l i n e i n c e l l , c l o s e w i t h p i p e caps, t e s t .

Thread

Remove t o o l s , e t c . ,

r e p l a c e block, remove maintenance s h i e l d , s e a l membrane, i n s t a l l t o p blocks.

I n s p e c t FV-105 (Job HC-6) Purpose

- To

a s c e r t a i n t h e l o c a t i o n , n a t u r e and probable cause of

t h e leak. General Procedure c o o l i n g - a i r shroud. nique.

- (In

hot c e l l )

- If

l e a k i s i n FV-105, remove

I n s p e c t e x t e r i o r v i s u a l l y and by d y e - p e n e t r a n t t e c h -

S e c t i o n and examine m e t a l l o g r a p h i c a l l y .

--Excise F u e l Pump Sampler Cage and B a f f l e ( J o b R C - 1 3 ) Purpose nation.

- To

remove t h i s assembly t o a h o t c e l l f o r d e t a i l e d exami-

To provide an opening through which t h e i n t e r i o r of t h e f u e l -

pump bowl can b e viewed. General Procedure viewing d e v i c e .

- S e t up maintenance

shield,

Remove FP h e a t e r s and l e a d s .

i n s t a l l l i g h t s and

Use plasma t o r c h t o c u t

away i n t e r f e r i n g p o r t i o n of s u p p o r t p l a t e and r i n g .

Remove f l a n g e d s e c -

t i o n of sampler tube, then c u t tube j u s t above bowl c o o l i n g shroud. o u t r i n g of shroud around t u b e .

Cut

Use plasma t o r c h t o c u t through upper

head of FP bowl i n c i r c l e c l o s e around sampler b a f f l e .

L i f t s h o r t sec-

t i o n of sample l i n e w i t h a t t a c h e d l a t c h s t o p , c a p s u l e cage and b a f f l e i n t o s h i e l d e d c a r r i e r and d e l i v e r t o h o t c e l l .

--I n s p e c t Sampler Cage and B a f f l e ( J o b HC-4) Purpose

- To

determine t h e n a t u r e of any d e p o s i t s on t h e m e t a l s u r -

f a c e s i n s i d e and o u t s i d e of t h e b a f f l e and how t h e d e p o s i t i o n v a r i e d a t and above t h e s a l t - g a s i n t e r f a c e .

To s e e i f t h e 10-g c a p s u l e t h a t w a s

dropped i n March be.

1968 i s s t i l l wedged o u t s i d e t h e cage as it seemed t o

To examine specimens from s e l e c t e d s p o t s f o r evidence of c o r r o s i o n . General Procedure

view and photograph.

(In hot c e l l )

- Remove assembly

S e c t i o n v e r t i c a l l y and h o r i z o n t a l l y .

from c a r r i e r , Remove de-

p o s i t s from some s e c t i o n s mechanically, from o t h e r s chemically.

Prepare

specimens f o r m e t a l l o g r a p h i c examination.

View I n s i d e Pump Bowl (Job RC-14) Purpose

- To

make o b s e r v a t i o n s and photographs t h a t can be used

with t h e r e s u l t s of Job HC-4 t o d e s c r i b e t h e d e p o s i t i o n of s a l t m i s t , o i l r e s i d u e s (and perhaps f i s s i o n p r o d u c t s ) on t h e v a r i o u s s u r f a c e s exposed t o s a l t and gas i n t h e pump bowl. General Procedure ( J o b RC-13)

- After

removal of t h e sampler cage and b a f f l e

l o o k down a t bottom head below h o l e and photograph it.

In-

s e r t viewing device w i t h l i g h t through t h e h o l e ( a b o u t 3-in. diameter)

Look a t and photograph t o p head, t o p and bottom of "shed r o o f , " overflow l i n e , v o l u t e s u p p o r t c y l i n d e r , and v o l u t e . and l a t c h key i n bottom head.

Look f o r remains of c a p s u l e s

Remove viewing equipment.

Close F u e l Pump Bowl (Job RC-15) Purpose

- To

p r e v e n t f r e e communication between t h e i n s i d e o f t h e

f u e l system and t h e c e l l atmosphere under c r e d i b l e f u t u r e c o n d i t i o n s . (There would seem t o b e no way f o r t h e p r e s s u r e d i f f e r e n t i a l t o exceed

5 p s i o r t h e temperature t o exceed 200째F.) General Procedure a g a i n s t t h e pump t a n k .

- Prepare

a p a t c h t o f i t over t h e h o l e and s e a l

Apply t h e patch, remove t o o l s .

P r e p a r e f o r Core Work ( J o b RC-2) Purpose

- To

c l e a r t h e way for opening t h e c o r e a c c e s s f l a n g e .

make t h e c o n t r o l rods a v a i l a b l e f o r i n s p e c t i o n .

General Procedure

- Set

up maintenance s h i e l d .

(The upper b l o c k s

and p a r t of t h e r e a c t o r c e l l membrane w i l l have been removed i n Job RC-1.) Disconnect c o n t r o l rod d r i v e s and move t o s p a r e c e l l . and hang i n r e a c t o r c e l l .

Remove c o n t r o l rods

Remove t h e g r a p h i t e sampling s t a n d p i p e .

Clear

away c o n t r o l rod d r i v e s h i e l d i n g , b r a c i n g and any o t h e r o b s t r u c t i o n from the reactor access flange area.

Remove Core Access Plug and Rod Thimbles ( J o b RC-7) Purpose

- To

g i v e a c c e s s t o t h e i n t e r i o r of t h e r e a c t o r vessel.

p e r m i t i n s p e c t i o n of Hastelloy-N t h a t has r e c e i v e d l o n g exposure i n t h e

To permit examination of p l u g s u r f a c e s f o r evidence of u n u s u a l de-

core.

p o s i t i o n around t h e s a l t - g a s i n t e r f a c e . General Procedure - U n b o l t ,

l i f t out, and hang i n t h e r e a c t o r c e l l .

--Remove Some Core G r a p h i t e ( J o b RC-8) Purpose

- To

provide a bar of g r a p h i t e from t h e c o r e f o r examination

i n a hot cell. General Procedure l i v e r t o hot c e l l .

- Lift

one of c o r n e r b a r s i n t o a c a r r i e r and de-

( A second bar, perhaps t h e c e n t e r , may a l s o be r e -

moved.)

View Core and I n s i d e of Reactor V e s s e l Heads ( J o b RC-9) Purpose

- To look f o r

evidence of u n u s u a l d e p o s i t s i n l o w - v e l o c i t y

r e g i o n s , any fragments of g r a p h i t e or o t h e r l o o s e o b j e c t s , and any broken graphite stringers. General Procedure

- Lower

viewing device and l i g h t i n t o upper head.

V i e w and photograph i n s i d e of c o r e a c c e s s nozzle and f u e l o u t l e t on t h e way down,

View and photograph i n upper head w i t h p a r t i c u l a r a t t e n t i o n t o

t o p of g r a p h i t e and r e t a i n i n g w i r e s . f o r a n y t h i n g unusual.

Lower device through c o r e , scanning

View and photograph h o r i z o n t a l g r a p h i t e , s u p p o r t

g r i d , f l o w d i r e c t o r s and s u r f a c e of lower head.

Remove viewing d e v i c e s .

Close Reactor Access (Job RC-10) Purpose

- To

p r e v e n t f r e e communication between t h e i n s i d e of t h e

f u e l system and t h e c e l l atmosphere under c r e d i b l e f u t u r e c o n d i t i o n s . General Procedure

- Install

a b l a n k f l a n g e on c o r e a c c e s s nozzle.

--Cut Off

P i e c e of Rod Thimble ( J o b RC-11)

Burpose

- To

o b t a i n a p i e c e of thimble f o r c l o s e examination i n

hot c e l l . General Procedure

- With

a c c e s s nozzle and a t t a c h e d rod t h i m b l e s i n

t h e r e a c t o r c e l l , s e v e r No. 3 thimble j u s t below t h e p i p e - t o - t u b e t r a n sition,

D e l i v e r t h e lower end of thimble, i n c l u d i n g t h e guide assembly

and t h r o a t , t o h o t c e l l .

I n s p e c t Core G r a p h i t e B a r ( J o b HC-2) Purpose

- To

s e e i f t h e r e i s any p e r c e p t i b l e d i f f e r e n c e between con-

d i t i o n of t h i s g r a p h i t e and t h a t of t h e g r a p h i t e i n t h e specimen a r r a y s . To look f o r evidence of u n u s u a l f l o w s i t u a t i o n s . G e n e r a l Procedure

( I n hot c e l l )

- Examine

s u r f a c e s , observe p a t -

t e r n s r e l a t e d t o flow i n channels, l o o k f o r any evidence of s a l t i n t r u s i o n between b a r s .

S e c t i o n b a r and determine d i s t r i b u t i o n of s a l t c o n s t i t u e n t s

and f i s s i o n p r o d u c t s i n g r a p h i t e .

I n s p e c t C o n t r o l Rod Thimble ( J o b HC-3) Purpose

- To

a t t e m p t t o determine why a r o d hung on withdrawal and

t h e replacement rod ( w i t h beveled s h o u l d e r s on t h e end f i t t i n g ) d i d n o t .

To s e e i f m o i s t u r e or f o r e i g n matter ( s u c h as fragments of blower d r i v e b e l t s ) i n t h e c o o l i n g a i r had s i g n i f i c a n t d e l e t e r i o u s e f f e c t s .

To de-

termine i f s u r f a c e s exposed t o s a l t were corroded o r otherwise a f f e c t e d . General Procedure

of guide bars.

(In hot c e l l )

- Cut

open t o r e v e a l lower ends

See i f bars a r e l o o s e o r warped.

evidence of c o r r o s i o n ,

Examine s u r f a c e s f o r

Excise S e c t i o n s of F u e l P i p i n g (Job RC-17) Purpose

- To

remove s u r f a c e s from h o t and c o l d s i d e s of f u e l c i r c u -

l a t i o n l o o p f o r c l o s e examination, c l o s i n g up t h e openings a f t e r t h e removal

General Procedure

- Set

up maintenance s h i e l d .

U s e an 1 8 - i n . - d i a

c u t t i n g wheel on a mast-mounted t o o l t o c u t o u t 1 2 - i n . s e c t i o n s of 5 - i n . pipe.

One s e c t i o n w i l l be from Line 101 between t h e pump d i s c h a r g e and

f r e e z e f l a n g e 101; t h e o t h e r from t h e h o r i z o n t a l run of l i n e 102 between t h e h e a t exchanger e x i t and f r e e z e f l a n g e 102. shielded c a r r i e r s t o hot c e l l s .

Transfer sections i n

Close s e v e r e d ends of p i p e i n c e l l with

caps s u i t a b l e f o r a n t i c i p a t e d c o n d i t i o n s .

I n s p e c t S e c t i o n s of Fuel P i p i n g (Job HC-5) Purpose

- To

determine e f f e c t s of c o r r o s i o n and f i s s i o n p r o d u c t de-

p o s i t i o n f o r comparisons between "hot" and "cold" s e c t i o n s and w i t h o t h e r i n d i c a t i o n s ( c o r e specimens, r o d thimbles, remote gamma-ray s p e c t r o m e t r y ) . General Procedure

(In hot c e l l )

- Examine

s u r f a c e s metallog-

r a p h i c a l l y and f o r e l e m e n t a l composition of d e p o s i t s .

Remove Heater H-103 from F u e l Drain Line (Job RC-3) Purpose

- To

provide an opening through which equipment can b e i n -

s e r t e d t o view beneatk r e a c t o r v e s s e l . General Procedure

- Set

To t e s t m a i n t a i n a b i l i t y .

up maintenance s h i e l d .

P u l l H-103 and s t o r e

i n reactor c e l l ,

--View Drain Line I n s i d e Reactor Furnace (Job RC-4) Purpose

- To

l o o k f o r e f f e c t s of o p e r a t i o n and evidence of i n -

cipient trouble. General Procedure

- Insert

viewing device w i t h l i g h t through H-103

p o r t and guide s l e e v e i n thermal s h i e l d .

View and photograph o u t s i d e of

FV-103 e n c l o s u r e , w i t h a t t e n t i o n t o c o n d i t i o n of s h e e t metal, i n s u l a t i o n and thermocouples.

S c r u t i n i z e and photograph d r a i n l i n e and v i s i b l e

p o r t i o n of r e a c t o r v e s s e l , with emphasis on d r a i n l i n e n e a r v e s s e l juncture.

Remove viewing device.

--Excise I n l e t S e c t i o n of Main Charcoal Bed (Job 0-5) Purpose

- To

g e t s h o r t s e c t i o n a t i n l e t of one main c h a r c o a l bed t o

h o t c e l l f o r examination, General Procedure bed p i t .

- Set

up work s h i e l d .

Lower water i n c h a r c o a l

Sever 1/2-inch i n l e t l i n e n e a r l - l / 2 - i n c h

c a p a t bed e n t r a n c e .

Cut bed a b o u t 6 i n c h e s below cap, t a k i n g c a r e n o t t o s p i l l c h a r c o a l . move i n s h i e l d e d c a r r i e r t o h o t c e l l .

Re-

Cap 1/2-inch l i n e and bed (1-1/2-

inch pipe).

--I n s p e c t I n l e t S e c t i o n of Main Charcoal Bed (Job HC-7) Purpose

- To

determine r e a s o n f o r r e c u r r e n t plugging.

i f a d s o r p t i v e c a p a c i t y of c h a r c o a l i s s i g n i f i c a n t l y reduced.

To determine If so, t o

determine t h e reason. General Procedure packed i n l e t s e c t i o n . xenon o r krypton.

- Cut

open, l o o k a t , and photograph s t e e l - w o o l -

Remove c h a r c o a l .

T e s t a d s o r p t i v e c a p a c i t y for

C o m p a r e w i t h r e s u l t of s a m e t e s t on unused c h a r c o a l

of same t y p e .

E x c i s e S e c t i o n s of R a d i a t o r Tubing ( J o b 0-2) Purpose

- To

provide specimens from "hot" and "cold" ends of tube

bundle General Procedure

- Cut

o u t a 6 - i n c h s e c t i o n of 3/4-inch tube n e a r

i n l e t end of tube bundle and one n e a r o u t l e t end. Ceramics D i v i s i o n l a b o r a t o r y ,

D e l i v e r t o Metals and

(These specimens w i l l n o t be r a d i o a c t i v e ,

b u t p r e c a u t i o n s w i t h r e g a r d t o b e r y l l i u m must b e o b s e r v e d , ) W

ends of t u b e s i n r a d i a t o r .

Close c u t

I n s p e c t S e c t i o n s of R a d i a t o r Tubing ( J o b L-1) Purpose

- To

l o o k f o r e f f e c t s of c o r r o s i o n and mass t r a n s p o r t .

General Procedure - Examine m e t a l l o g r a p h i c a l l y .

Determine compo-

s i t i o n of any d e p o s i t s .

Excise TC Wells a t R a d i a t o r (Job 0 - 3 ) Purpose

- To

remove t h e s e w e l l s f o r i n s p e c t i o n .

General Procedure

- Observing

beryllium precautions, c u t out a 6-in.

s e c t i o n of 5-inch c o o l a n t p i p i n g c o n t a i n i n g r a d i a t o r i n l e t thermocouple Cut o u t a similar s e c t i o n w i t h t h e o u t l e t w e l l .

well,

laboratory.

Deliver t o M & C

Cap severed ends of p i p e i n c o o l a n t system.

I n s p e c t Coolant TC Wells (Job L-2) Purpose trouble.

- To

look f o r evidence of any u n u s u a l c o r r o s i o n o r i n c i p i e n t

( P i p e s u r f a c e s can a l s o be compared w i t h s u r f a c e s i n r a d i a t o r

t u b e s .) General Procedure

- Examine

metallographically.

Determine compo-

s i t i o n of any d e p o s i t s .

T e s t d / p System on Coolant S a l t Flowmeter (Job 0- 1) Purpose

- To

determine t h e o u t p u t from f l o w t r a n s m i t t e r s FT-201A

and FT-201B as a f u n c t i o n of t h e d i f f e r e n t i a l p r e s s u r e a p p l i e d t o t h e cells.

The c a l i b r a t i o n i s t o be done i n p l a c e t o a v o i d any movement of

t h e s a l t - N a K diaphragm s e a l s or t h e N a K - f i l l e d l i n e s l e a d i n g t o t h e d/p c e l l s which conceivably could cause a s h i f t i n t h e r e a d i n g s . General Procedure - Cut o u t a s e c t i o n of l i n e - 2 0 1 j u s t ahead of upstream d/p connections.

I n s t a l l plug i n v e n t u r i between t h e upstream and

t h r o a t d/p c o n n e c t i o n s .

Cap t h e l i n e and apply argon p r e s s u r e t o s e c t i o n

w i t h upstream d/p connections.

Record o u t p u t f o r b o t h f l o w t r a n s m i t t e r s

as a f u n c t i o n of a p p l i e d d/p over f u l l range of t r a n s m i t t e r s .

Remove Coolant Pump Rotary Element ( J o b Purpose

- To

0-4)

p e r m i t d e t a i l e d i n s p e c t i o n of t h e r o t a r y element and

i n t e r i o r of t h e pump. General Procedure

- Disconnect,

v i s i o n pump f a c i l i t y i n Y - 1 2 .

remove and d e l i v e r t o R e a c t o r D i -

A f t e r i n s p e c t i o n of i n t e r i o r of pump, i n -

s t a l l c o v e r p l a t e t o c l o s e t h e opening.

I n s p e c t Coolant Pump Rotary Element (Job L-3) Purpose

- To

determine e f f e c t s of o p e r a t i o n .

To o b t a i n i n f o r m a t i o n

on which t o b a s e judgement of s e r v i c e a b i l i t y and remaining l i f e . General Procedure

- Observe

Look f o r unusual rubbing.

evidence of o i l l e a k a g e and decomposition.

Check key dimensions a g a i n s t o r i g i n a l s .

--Examine C o n t r o l Rods (Job RC-5) Purpose

- To

s e e i f t h e r e i s any evidence of unusual rubbing or

damage on t h e o u t s i d e of t h e rod. General Procedure

- With

t h e rod hanging i n t h e r e a c t o r c e l l , ex-

amine c a r e f u l l y through p e r i s c o p e .

Remove S e c t i o n of C o n t r o l Rod (Job RC-6) Purpose

- To

g e t a c t i v e s e c t i o n of c o n t r o l r o d t o h o t c e l l for

inspection. General Procedure

- Cut

C o n t r o l Rod No. 3 j u s t above poison e l e m e n t s ,

D e l i v e r lower end of rod, w i t h elements, t o h o t c e l l .

I n s p e c t C o n t r o l Rod and Elements (Job HC-1) Purpose of r o d .

- To

l o o k f o r p o s s i b l e e x p l a n a t i o n of changes i n s t i f f n e s s

To i n s p e c t elements for e f f e c t s of exposure.

- Remove

General Procedure

poison elements.

Examine hose f o r degree

of o x i d a t i o n and roughening of s u r f a c e s t h a t s l i d e when hose i s f l e x e d . Measure canned elements.

If any can i s swelled, c u t open and determine

c o n d i t i o n of ceramic.

Remove and I n s p e c t Heater U n i t s ( J o b Purpose

- To

RC-16)

determine c o n d i t i o n of u n i t s .

To judge d i f f i c u l t y of

To make way f o r e x c i s i o n of s e c t i o n s of f u e l p i p e .

r e p a i r and replacement.

- Set

General Procedure

up maintenance s h i e l d .

Disconnect h e a t e r

H-101-1. L i f t and s e t back i n p l a c e , n o t i n g d i f f i c u l t i e s . equipment s t o r a g e c e l l ,

Remove t o

Repeat f o r h e a t e r H-102-3.

View.

T e s t F u e l Pump Motor Removal (Job RC-1)

Purpose over

- To

d e t e r n i n e i f u n b o l t i n g system i s s t i l l o p e r a b l e a f t e r

4 y e a r s ' exposure. General Procedure

- Unbolt

and remove a l l t o p b l o c k s .

Cut and r e -

move s e c t i o n s of membrane as r e q u i r e d for t h i s and l a t e r j o b s . maintenance s h i e l d .

Disconnect power and i n s t r u m e n t l e a d s t o pump motor.

Unbolt o i l and water l i n e s . flange.

S e t up

Loosen s e v e r a l e x t e n s i o n b o l t s on motor

If motor must be o f f f o r J o b RC-13,

proceed t o remove motor t o

equipment s t o r a g e c e l l .

Disconnect Fuel Sampler Line (Job RC-12) Purpose

- To

determine i f d i s c o n n e c t system i s s t i l l o p e r a b l e a f t e r

long exposure t o c e l l environment.

To p r e p a r e for e x c i s i o n of sampler

cage and b a f f l e . General Procedure

- Set

up maintenance s h i e l d .

Remove clamps from

f l a n g e s on s p o o l p i e c e .

Use i n s t a l l e d j a c k t o compress bellows and c l e a r

flanges.

Note any d i f f i c u l t i e s , judge p r a c t i c a l i t y of pro-

Swing a s i d e .

v i s i o n s f o r remote removal of pump bowl.

27 SCHEDULF Some of t h e n o n - r a d i o a c t i v e work, such as t h a t on t h e c o o l a n t system, may b e g i n b e f o r e J u l y 1,

1970 i f

funds a r e a v a i l a b l e .

Before t h e work i n

t h e r e a c t o r c e l l and d r a i n t a n k c e l l can commence, t o o l s must be procured and t e s t e d , d e t a i l e d procedures must be developed, and t h e p l a n s must be reviewed and approved by program and s a f e t y groups. July

A t a r g e t d a t e of

6 has been s e t f o r t h e beginning of t h e i n - c e l l work. Table 2 shows t h e sequence of i n - c e l l work t h a t now a p p e a r s most

l o g i c a l , p r o g r e s s i n g g e n e r a l l y from j o b s i n v o l v i n g l e s s chance of contamin a t i o n t o t h o s e l i k e l y t o involve t h e most contamination of t h e c e l l , t o o l s , and s h i e l d i n g .

The e s t i m a t e d d a t e s t e n d t o be o p t i m i s t i c s i n c e

t h e y i n c l u d e no allowance for "unusual" d e l a y s .

Although c r i t i c a l - p a t h

s c h e d u l i n g was used i n p l a n n i n g maintenance and m o d i f i c a t i o n work througho u t t h e o p e r a t i o n of t h e MSRE, t h i s type of diagram i s n o t shown h e r e because t h e i n - c e l l work r e q u i r i n g t h e p o r t a b l e maintenance s h i e l d f a l l s on

a s i n g l e p a t h and most of t h e o t h e r work can be done as " f i l l - i n " j o b s whenever it i s most convenient. A g o a l w i l l b e t o have v i r t u a l l y a l l t h e work of s e c u r i n g t h e p l a n t

1970. H o t - c e l l work and 4, 1970. These d a t e s may be

f i n i s h e d by October 2,

a n a l y s e s should be com-

p l e t e d by December

extended i f , f o r example,

it i s more economical t o do s o t h a n t o work overtime. STAWS

A s of A p r i l 10, t h e g e n e r a l s t r a t e g y has been decided f o r each j o b and p l a n s have been sketched i n enough d e t a i l t o e s t a b l i s h confidence i n t h e f e a s i b i l i t y (by one means or a n o t h e r ) of a l l t h e important j o b s .

s h e a r and plasma t o r c h have been s e l e c t e d f o r procurement, o t h e r t o o l s and t h e maintenance s h i e l d are b e i n g r e a d i e d , and t h e p r o t o t y p e f u e l pump i s on hand t o be s e t up i n t h e maintenance p r a c t i c e c e l l as a mock-up f o r developing t h e procedure f o r c u t t i n g i n t o t h e pump bowl.

28 Table 2 Sequence

and E s t i m a t e d Datesb of Work

I n MSRE Reactor and Drain Tank C e l l s and X - 1 0 Hot C e l l s

Reactor and Drain Tank C e l l s

A v a i l a b l e t o Hot C e l l s

July 6

10 l5

m-105 v i c i n i t y

E-1

View

RC- 1

T e s t FP motor removal

RC-2

Prepare f o r c o r e work

RC- 3

Remove h e a t e r H-103

RC-4

V i e w beneath r e a c t o r

RC-5

Examine c o n t r o l r o d s

RC-6

Remove s e c t i o n o r rod

RC-7

Remove c o r e a c c e s s p l u g

RC- 8

Remove some g r a p h i t e

RC-9

View c o r e Close c o r e a c c e s s Cut rod thimble

C o n t r o l r o d and elements Core g r a p h i t e

Rod thimble

Open sampler tube RC- 13

E x c i s e cage and b a f f l e

RC-14

View i n FP bowl

15 RC-16

Close FP bowl Remove and check h e a t e r s

RC-17

Cut 5 - i n . f u e l p i p e

5-inch p i p e

E x c i s e FV-105

FV-105

RC-

21 Sep.

4 18

Cage and b a f f l e

Seal cells Decontaminate

a The j o b s l i s t e d f o r t h e MSRE c e l l s cannot b e done i n p a r a l l e l because a l l r e q u i r e t h e p o r t a b l e maintenance s h i e l d . The sequence was determined mainly by contamination c o n s i d e r a t i o n s . Items w i l l be a v a i l a b l e f o r h o t - c e l l work i n t h e sequence l i s t e d . bThese d a t e s a r e based on p r e l i m i n a r y procedures and make no allowance f o r u n u s u a l d e l a y s , Y

ORNL-TM- 2974 INTERNAL DISTRIBJTION

1, R . G. A f f e l

51.

M, T. Kelley

2 * J. 3. C . 4. S . 5. M. 6. E.

52.

H . G . Kern E. M. King S. S. K i r s l i s A . I. Krakoviak Kermit Laughon, AEC-OR0 M. I. Lundin R e N. Ly on H. G. MacPherson R. E . MacPherson H. E. McCoy H . C . McC u r dy C . K. McGlothlan T . W. Mc I n t o s h, AEC- Was h i n g t on L. E . Mc Nee s e J. R. McWherter A. J. M i l l e r R. L. Moore H. H. Nichol E . L. N i c h 01son A. M. Perry H. B. P i p e r B. E . P r i n c e G. L. Ragan J . L. Redf ord M. Richardson D. R. Riley, AEC-Washington M. W. Rosenthal H. M. Roth, AEC-OR0 A . W Savolainen T. G. S c h l e i t e r , AEC-Washington J . J. S c h r e i b e r , AEC Washington Dunlap S c o t t M. Shaw, AEC-Washington M. J . Skinner G. M. S l a u g h t e r W. L. Smalley, AEC-OR0 I. Spiewak D. A. Sundberg D. B. Trauger R. E . Thoma A . A. Walls B. H. Webster A. M. Weinberg J. R. Weir K. W. West

7. 8. 9. 10. 11. 12*

13. 14# 15.

16. 17. 18. 19. 200 21. 22. 23. 24. 25. 26. 27e 28. 29. 30.

32.

33, 34. 35. 36, 37. 38. 39. 40-44.

45. 46. 47. 48. 49. 50.

L. Anderson F. Baes E. Beall Bender S. B e t t i s D. S. B i l l i n g t o n F. F. Blankenship R . Blumberg R . B. B r iggs E . G . Bohlmann N. E. Bolton c . J, Borkowsk i G . E. Boyd G . c. Cain R . H. Chapman R . L. C l a r k E . L. Compere w o H. Cook D. F. Cope, AEC-RDT W. B. C o t t r e l l J. L a Crowley F, L. C u l l e r D. M . Davis s. J. D i t t o w. P. E a t h e r l y David E l i a s , AEC -Washington J. R. Enge 1 D. E. Ferguson L. M. F e r r i s A . P. Fraas J . H. Frye J. E . Fox, AEC-Washington C . H. Gabbard W. R. Grimes - G. M. Watson A. G. G r i n d e l l R. H e Guymon Norton Haberman, AEC-Washington P. A. Halpine, AEC-Washington P, N. Haubenreich

P o P. Holz A. Houtzeel W , H. Jordan

S, I. Kaplan P. R, Kasten R . G. Ked1

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- 81. 82.

83 84. 85. a

86. 87 88 89 90 91. 0

92.

93 94 95 96 97. 98 99. 0

30 ORNL- TM- 29-74

I n t e r n a l D i s t r i b u t i o n (continued)

M. E. Whatley J. C . White - A . S. Meyer G. D. Whitman 103. E . J . Witkowski 104. C . H. Wodtke 105. Gale Young 106-108. C e n t r a l Research Library (CRL) log-llO. Y - 1 2 Document Reference S e c t i o n (DRS) 111-113. Laboratory Records Department (LRD) 114. Laboratory Records Department - Record Copy 115. ORNL P a t e n t O f f i c e 100. 101. 102.

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