CBECEWED BY TIE g7 ggmyy S

 

   

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| ORNI. m 3524

   

 

 

OPERAT!ON OF THE SAMPLER-ENRICHER
. INTHE
MOLTEN SALT REACTOR EXPERIMENT o

 

 
  

 

 

 

 

el Hfl"‘:['fins documen! “contains lnformuhon of a prehmmury nurure__
" and was pfepured primarily for intemal use ot the Oak Ridge National ="
Loboratory. It is-subject to revmon ‘or correcnon ond therefore does' :

- not represem o f:nal ‘teport.” : : _

 

 BISTRIBUTION OF THIS DOCUMENT IS UNLUATED

  
 

[E——

g S BRI 100, 4 R e £ e e A

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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 sny of their employees, nor any of their contractors,
subcontractors, or their employees, makes any warranty, express or implied, or
assumes any 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,

 

 

 

 
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ORNL-TM-3524

Contract No. W-7405-eng-26

Reactor Division

OPERATION OF THE SAMPLER-ENRICHER
| in the
MOLTEN SALT REACTOR EXPERIMENT

"R. B. Gallaher

 

 

{ This :eport 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 assumes any
legal Tiability . or responsibility for the accuracy, com- | .
pleteness or usefulness of any information, apparatus, |
product or process disclosed, or represents that its use
would not infringe privately owned rights, :

 

 

 

~ OCTOBER 1971

OAK RIDGE NATIONAL LABORATORY
Oak Ridge, Tennessee
- operated by
'UNION CARBIDE CORPORATION : )
for the .
U.S. ATOMIC ENERGY COMMISSION

PISTRIBUTION OF THIS DOCUNEKT IS uau&a% |
 

 

 

 

 

 

 

 

 

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Abstract . . . « . . .
Introduction . . . . .
Design Criteria . . . .
Description . . . . . .

Equipment . .-. .

Capsules e e & ob

Instrumentation . -

Operating Procedures .
| Sampling . . . .
Enriching . . . .
‘Operating Experience .

Sample Capsules .

Manipulator R P -." . ..‘- . o . .

*

-

.

iii

Contents

Operational and Maintenance Valves

Access Port . . .

Removal Valve. . . . .

Removal Seal . . .

Lighting and Viewing .

Vacuum Pumps . . .

. Electric Penetrations and Wiring
Instrumentation, ..

SUMMAry . 4 . o4 . . s

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*

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Operation of the Sampler-Enricher
~ 1in the
Molten Salt Reactor Experiment

R. B. Gallaher

Abstract

The sampler-enricher for the Molten-Salt Reactor experi-
ment was designed to remove 10-g samples and to add 90-g in-
crements of uranium to the pump bowl. During the five-year
service life the equipment was used to isolate 593 samples
and. to make 152 fuel additions. It was still operable when
the reactor was shut down. The major maintenance jobs in-
volved the manipulator boots and the capsule drive unit, -

. The boots were changed 17 times. The drive unit was replaced
once and repaired four other times. There were some minor re-
"pairs. No excessive release of gaseous or particulate matter
occurred during operation or maintenance of the equipment.

Keywords: MSRE, fluid-fueled reactors, fused salts,
- fuels, sampling, loading, refueling, on-line, equipment,
instrumentation, remote maintenance, containment, closures,
manipulator.

Introduction

' The Molten-Salt Reactor Experiment was conducted to demonstrate the

engineering and technical feasibility'of high-temperature, cireulating

-~ fuel reactors. The*expetimentiserved,as a test of (1) the compatibility
of the fluoride salt withfthe stfnctural material and the'graphite mod-

erator and (2) the stability of the salt during extended operation in a
high-radiation field, Results were inferred in part from analysis of

samples of the circulating salt obtained while the reactor was operating

at power,

“The method selected for sampling was to lower a small capsule into

"the salt reservoir in the fuel-pump bowl., Two streams of fuel salt,

. having a combinedrflow_rate;of,about 65 gpm;'flowed from the circulating

loop through this-region;":Saltivolume in this‘reSérvoir, which served
as the expansion volume for the fuel loop, was about 30 gallons. Thus, a

sample from this region should be representative of the salt in the main
 

 

circulating stream. The sample was removed from the reactor and sent to
a high-radiation level analytical laboratory for chemical and isotopic
analysis.

Since the sampling system provided a ready access to the fuel stream,
it was also used to add uranium to replace the material that was consumed
by fissioning and to overcome the decrease in reactivity resulting from
the buildup of fission-product poisons in the system. Poison material’
also could be added, if needed, for reactivity control, using the equip-
 ment even in the event of a complete loss of electric power.
| Removing samples of highly radioactive salt from the: circulating
stream of an operating reactor_presenced some difficult design problems.
Operators had to be protected from excessive exposure to radiaticn and
from gaseofis fission products, The sample and the reactor System'had to
be protected at all times from contsminscion by air and water. This re-
port presents a brief description of the?mechanical design and operating
procedures and a discussion of the majorgmaintenance problems encountered
for each of the various components duriné the fivc years thac.the sampler-

enricher was operated.

Design Criteria

The following criteria were used ingdesigning the sampler-enricher.?

1. Failure of any one component must not result in a massive leak
of radioactivity to the atmosphere, Two barriers were required between
any source of radioactivity greater than 1000 curies and the atmosphere.

2. An inert atmosphere was required at all times in the sampling
.equipment and around the sample until it was delivered to the analytical
laboratory. '

3. The release of contamination to the atmosphere, both gaseous
and particulate matter, must be less than the limits imposed by laboratory
radiation safety standards. .

4. The equipment must be capable of isolating three samples per
day (one per shift).
5. Anticipated operating life was one year or about 1,000 sampling

cycles.

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6, The design pressure was 50 psig for primary containment areas
and 40 psig for secondary containment areas. Design temperature was 100°F,
7. Replacement of each individual component must be possible, if

.replacement were desired or needed.
8. Each enriching capsnle must add about 90 g of ?®?U to the sys-

tem, the amount needed for about one week of full power operation.

' 'Description

Equipment
The MSRE Design and Operations Report® covers the design specifi-

cations for the sampler-enricher system and describes each component in
detail. How the various.compOnents fulfilled the containment and the me-
chanical requirements for'sampling and for adding enriching salt to the
reactor is discussed in the following paragraphs.

Figure 1 is a schematic diagram of thevsampler—enriCher. Note that
both primary and secondary containment barriers of the reactor had to be
penetrated to reach 1nto the fuel salt from the operating area. In order
to assure that there were always at least two barriers between the fuel
system and atmosphere and between the sample and atmosphere, the equip-
ment was compartmentalized; Adjacent compartments or areas were sepa-

rated by buffered, double-sealed barriers. The pressure of the buffer

-gas was used to define when a barrier was closed.

For ease of identification, containment areas were'classified as

follows. Portions that were part of, or opened directly to, the primary

system were designed as 1A lB and 1C. Secondary containment areas,

~such as the valve box, ‘were designated as 2A and 2B The outer compart-
-ment which was secondary containment during certain phases of the operating

. procedure was designated as 3A

The system consisted of a transfer tube which connected the two-

_compartment dry box (see Fig 1) to the gas space ‘of the pump bowl. The

capsule, which was connected to the drive unit cable by a special latch,
was lowered through the transfer ‘tube into a guide cage beneath the salt

surface in the pump bowl. It was then pulled up through the tube and two
 

 

 

 

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CAPSULE DRIVE UNIT—
LATCH-_|
ACCESS PORT~—

AREA {C
(PRIMARY CONTAINMENT) —

1

SAMPLE CAPSULE

DR

 

 

 

       
 

B
OPERATIONAL AND
MAINTENANCE VALVES 4 |
' B
SPRING CLAMP
DISCONNECT —
f —EXPANSION SECTION

TRANSFER TUBE
{PRIMARY CONTAINMENT

LATCH STOP
PUMP

i
— 7 MIST SHIELD

=t CAPSULE GUIDE

Ii

Fig. 1. Sampler-Enricher Schematic.

 
 
 
 
  

 

 

 

 

 

 

 

 

 

 

 

ORNL-DWG €3-5848R

REMOVAL VALVE AND
SHAFT SEAL

PERISCOPE
LIGHT

CASTLE JOINT (SHIELDED
WITH DEPLETED URANIUM)

MANIPULATOR .
AREA 3A {SECONDARY
CONTAINMENT )

SAMPLE TRANSPORT
CONTAINER

LEAD SHIELDING

AREA 2B (SECONDARY
CONTAINMENT)

852" ELEVATION
S

Ry

CRITICAL CLOSURES
REQUIRING A BUFFERED
SEAL _

1
 

 

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gate valves into the inner compartment (1C) of the shielded dry box.
Using a simple one-handed manipulator,and a periscope, the capsule was
disconnected from the latch and moved throngh an access port to a trans-
port -container located in the outer compartment (3A). After purging the
dry box, a removal tool was inserted through a ball valve and the trans-
port container was pulled up.into.a lead-shielded transfer cask. The
transfer cask was placed in a sealed_container-boited to the frame of a

truck and was moved to the high-radiation level analytical chemistry fa-

-cility located in the X-10 area of ORNL,

There were three barriers in the sampler-enricher. A system of
interlocks permitted only one to be opened at a time, The barriers were

(l) the operational valve and the maintenance valve which separated 1C

from the pump bowl (1A); (2) the access port which separated 1C from 3A;

~and (3) the removal valve which provided access to 3A from the operating

area.

At the time the capsule'was in the transport cask at the sampler

awaiting shipment to the analytical laboratory, the two barriers for the

B sample wererthe sealed'transport container and the high-bay area of the ;

building which was classified as a containment area. The truck used to
deliver the sample was brought into the building through an.air lock.
The transport container and the sealed container on the truck provided
the required. doublercontainnent.when the sample left.the reactor building.
An exhaust hood, connected to the building ventilation system, was
located above the sampler-enricher next to the transport cask to provide
controlled venting of any gaseous activity that might escape from the dry
box as the sample was being withdrawn. Also, the top of the sampler

shield was classified as a contaminated zone, "C Zone,“ to prevent spread-

._ing any particulate matter that might be released during samp11ng to other

1ocations. _

A vacuum pump connected to 1C and 3A was used to remove gaseous fis-
Sion products and atmospheric contamination from the dry,box. The pump
discharge was connected to the auxiliary charcoal bed. _AreaS'where lit-
tle or no radioactive. gases were anticipated were connected to another

vacuum pump for purging atmospheric contamination. These areas were
 

 

(1) the volume between the two manipulator boots, (2) the cover over the
operator end of the manipulator arm, and (3) the volume between the re-

moval valve and the removal seal.

Capsules

Ten-Gram Sample Capsule — About 10 grams of salt was required for
routine chemical analysis. A copper capsule used to isolate this size of
sample is shown in Fig. 2._»The capsule was 3/4 in., in diameter by 1.6 in.
long with.hemispherical top and bottom. Salt entered through two windows
whose location determined the quantity that was trapped. The solid metal
top provided sufficiefit“weight—to assure that the capsule would be sub-
merged in the salt. A key'was attached to the top of the capsule by a
loop of 1/32-in.-diam stranded-steel rope, which provided the flexibility
necéssary for the sample assembly to pass through the two 15-in.-radius
bends in the transfer tube. The key locked the assembly to the latch on
the drive unit cable.

Before use copper capsules were hydrogen fired at 1200°F for two
hours to remove surface contaminants and the oxide film, since oxide |
interfered with the uranium analysis. After firing, the capsules were

stored and assembled in an inert atmosphere.

Enriching Capsules — Figure 2 also shows an enrichifig capsule assem-
bly. The capsule was fabricated from 3/4=in. by 0.035~in.-wall nickell
tubing. .The béttom was spun shut on a 3/8-in. radius. A solid top was
welded in place. The capsule was 6-3/8 in. long and contained about
120 g of enriéhing salt (90 g of 2°°U). The holes, shown in the photo-
grapfi, were drilled after the capsule was filled and just prior to use.
Only the interior of the capsules was cleaned by hydrogen firihg{befdre
the salt was 1oadéd. The exférior was cleaned of dirt and gréase just |

before use.

Miscellaneous Capsule Types — During the 0pe:atinglife of the reac-
tor, the sampler-enricher was used for many other purposes besides taking
10-gram samples and adding enriching salt. In all cases, except one, the
dimensions of capsules for spe¢1a1 tests were equal to or less than those

of the enriching capsules. The one exception was used prior to power
 

 

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-

 

 

 

 

 

 

 

 

 

PHO 871hk

 
 

 

operation and could be handled with very little shielding. Maximum cap-
sule dimensions were limited by the inside dimensions of the transfer con-
tainer and by the radius of curvature of the transfer tube. Special de-
signs included capsules for exposing graphite to the salt and to the gas
in the pump bowl, dlssolv1ng various types of metal in the salt, trapplng
gas samples, taking 25 and 50 g salt samples, measuring salt surface ten-

sion, etc.

. Instrumentation

A complete descrlptlon of and specifications for the instrumentation
for the sampler-enrlcher is given in the MSRE Design and Operations Re-

port. »3

A brief discu531on_is given below for a few major components.
The gas pressure in the buffer zones between the two sealing sur-
faces of the barrier that separated the various compartments was used as
the indication that a barrier was sufficiently tight to provide contain-
ment. This gas pressure was monitored by a transducer located in the gas.
supply line as near the buffer zone as geometric restraints would permit.
The signal from the transducer wés used in the interlock circuit and was
monitored by a recorder. When a barfier.was open, the flow of gas from
the buffer zone resulted in a pressure drop across a flow restriction lo-
cated in therline upstream of the transducer resulting in a low buffer
pressure. The pressure drop was about 0.8 psi per cc/min of gas flow.
When a barrier was closed and sealed, the pressure was essentially the
same as the buffer gas supply or 40 psig. Before a barrier could be
opened the buffer gas in each of the other two barriers had to be at
least a specified minimum pressure, thus assuring that the leak rate from
the buffer zone through the seals was less than a predetermined amount,
The drive unit cable was driven by a gear so that one revolution of
the drive unit shaft produced a positive 8-in. movement of the cable.
Two torque transmitters connected mechanically to the shaft of the drive
unit and electricaliy to matching torque transmitters on a position indi-
cator mounted on the control board monitored the amount of cable that was

extended into the transfer tube. One pair of transmitters was calibrated
 

 

»

@

”

»n

to indicate the number of feet and the other pair to indicate the number

of inches of cable that had been inserted.' One revolution of the inch
indicator hand was equal to a movement of one foot of cable. B

Two sets of radiation detectors were installed,_EOne”set on the ex-
haust iine from 1C and 3A monitored the radiation level in the gas being
exhausted from these areas. They were also used to follow the effect of
purging the area with.clean gas. The other set was used to detect a re-
lease of gaseous activity to the'building ventilation system or back dif-
fusion of activity'through,the-buffer'gas lines-from the sampler toward
the panel board. In case of a high-actiwity indication, these detectors
caused several solenoid valves to close, blocking all lines that might
contain contaminated gas."

All penetrations into 3A and IC vere ‘either seal-welded or were
double-sealed with a leak-detector line attached between the seals. The
leak-detector system pressure'was"maintained above the equipment maximum
pressure so that any leakagerwould be_fron the buffer zone, thus guarding
against the release of activity to the operating’area androf'the dif-
fusion of oxygen and water into ‘the dry box.

‘Figure 3 shows part of the instrument cabinet and the dry box prior

to the installation of the shielding.

 

' Operating Procedures

'Ewery.engineer and"technician on the operating crew.at'the reactor
was trained in the use of the samplerwenricher. ‘A special sampling crew

was not used. Check 1ists were provided the operators, giving in detail

dall actions necessary for each step. Except for checking ‘the initial con-

dition of the equipment and for placing the unit on standby, which re-

quired only one man, a two-man crew was used One operated ‘the equipment
while the other read. the check 1ist and observed that the proper action
was taken. The timeweach,step was taken_was_recorded on the check list
along with the operator's,initials and.any pertinent comments on the
operation. Duringrthe-withdfawal of the sample from 3A, three operators

and an HP man were required. The third operator used damp cloths to
 

 

 

 

 

 

PHOTO 69L0%

10

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ding.

icher Before Installation of Shiel

Sampler-Enr

3.

Fig.

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e
 

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11

clean the surface of the removal tool as it was being withdrawn. - A

sampling sequence is outlined in the following discussion.

" Sampling

A-capsule assemhly was:aSSembled in a glove'hox and.put in the trans-
port container. The transport container was lowered through the removal
seal and removal valve onto the fixture 1ocated on the floor of 3A that
held the bottom section in place. The top of the transport container was
disengaged from the bottom and withdrawn so that the removal valve could
be closed, o | ' _ :

Next, the access port was opened-so that the capsule could be attached
to the latch on the drive unit cable. The manipulator was used for lifting

the capsule from the bottom of the transport container and for inserting

-the key into the latch. The access port was then closed 1C was evacu-

ated to remove air that might have been introduced with the capsule.
After the pressure of 1C was adjusted with helium to match that of the

pump bowl, the operational and maintenance valves were opened and the cap-

-sule was lowered 17 ft 5 in. to reach the pump bowl level. The capsule

remained in the salt for one minute to allow it to heat and £i11, It was
then withdrawn 18 in. into a vertical section of the transfer tube and
held 10 minutes to allow the salt to solidify to preventuspilling'while
moving through the sloping section of the tube., After the'sample was
withdrawn into 1C, the operational and maintenance valves were closed

At this point the atmosphere in area 1C contained a high concentra-
tion of radioactive gas that had come from the pump bowl and from the
sample. The area was purged with helium for 30 minutes, then evacuated
and refilled with clean helium.' -

The access port was opened 80 that the capsule could be detached from

;the latch by lifting the key slightly and rotating it forward and upward
with the manipulator. The capsule was placed in the bottom section of
- the transport container.r During handling, the operator ‘could see whether

'the-capsule contained. salt. _The¢access port was then closed,

After"opening the removalhvalve. the top of'the transport'container
was lowered over the bottom piece which held the sample, and the two

pieces were sealed together. - The removal seal prevented air from reaching
 

 

12

the sample and gaseous activity from being released to atmosohere during
this operation. The sample was withdrawn from 3A into the transfer cask.
During the withdrawal, the tee~handle extension of the transport container
was wiped with damp cloths to remove particulate contamination from its |
surface. Also, the removal valve was closed before the transport con-
tainer was moved past the removal seal. After disconnecting the tee-
handle, the transport container was locked into the transfer cesk; The
cask wss placed in two olastic bags and then clamped and sealed inside

the can on the sample truck. It was delivered to the high—radiation

level analytical laboratory for analysis.

Enriching

Using this same equipment, enriching salt (UF,-LiF) was added to the
reactor. Enrichmentsrcould be made with the reactor opersting at full
power, |

For the initial fueling of the reactor with ?3*°

U the capsules were
stored in a vault at the reactor site until they vere needed. Just prior
to use, ‘holes were drilled through the metal siderwalls ‘and into_the bot-
tom so that the melted enriching salt could flow from the capsule into
the pump bowl.

The procedure for adding enriching salt to the reactor was similar
to that for 1solating a sample, except for a few variations. During en-
riching a fnll capsule was inserred and an empty capsule was withdrawn.
The radiation level of the enriching salt was sufficiently low to allow
direct handling of the capsule with care exercised to prevent spreading
uranium contamination. This required that the necessary drilling and
‘weighings of the capsule be done in a glove box located near the sampler-
enricher. Empty capsules were sent to the high radiation 1eve1 labora-
tory for final weighing since the activity level was much too high
(>1,000 R/hr at 3 in.) to allow handling in the glove box.

When *°3%U and Pu were added to the reactor, the same tyne of cap—
sules were used. However, the preparation procedure prior to moving the
oapsule into the sampler-enricher had to be modified. The 2°°U capsules

~ had to be handled in a shielded facility, cell G of the Thorium Uranium .
 

 

 

o

-

)

13

Recycle Facility, because of -the 222 ppm of *??U in the feed and its as-
sociated radiation.é The capsules were filled, drilled, and loaded into
shielded carriers remotely and then transported to the reactor site. The
radiation level was about 1 R/hr at 3 inches for these capsules.

- For the Pu additions the capsules were .drilled before lbading.7 Then

_the holes were sealed with Zr foil. Pu in poWder form was packed into the

capsule. In the pump bowl the fuel salt dissolved the 2r allowing the Pu
to be released to the flowing stream. Handling of the Pu required extra

care to prevent the spread of alpha contamination.

 

Ofiérating Experience

During the five-year period that the reactor-waS*opefated, 593 sam-
pling cycles and 152 fueilenrichfiEnts were made. The equipment was still
in operéting condition whén‘therrééctor system was shut down. Important
operating experieficesrfor each of the major\components‘are recorded in the

following sections.

Sample Capsules

‘-_;Normal operating-proceduresucalled for the operator to test the

- proper attachment of the capsule to the drive unit latch by gently pulling

on the wire ropes of the capsule with the manipulator. On one occasion
the wire pulled free of the key during this check. The operator was able
to retain possession of,the capsule and 1lift it into 3A. The key remained

~in the latch and was remoVQd later. Following this,experience the ma-

terial for the top ofrthé:cépsu}e was changed from copper to nickel-plated
iron, so that a magnet could be used to retrieve an'assembly that might

be accidently dropped in 1C. The key was also fabricated from nickel-

" plated iron for the same reason.,

Capsules weré.éctually_drdpped.a few times® and récovergd with the

,magnet.,JWhile the ¢apsu1e'fiés being attached to the 1atch,*thé'opera-

tional valve was closed so a dropped capsule fell only about 15 inches

‘below the.accessupprt opening tthhe gate.of the valve. On two occasions,

noted later in the report, a capsule was dropped into the pump bowl during

. periods of abnormal operation when the operational and maintenance valves'
 

14

were open. VNo extensive attempt was made to recover the first capsule

at the time it was lost. After the second one was lost, a magnet was at-
tached to the drive unit and lowered into the pump bowl while the access

port remained open. The reactor was drained and the pdmp bowl was cooled

during the initial part of the recovery attempt. The magnet was moved up

"~ and down in the pump bowl by lifting and lowering the cable with the ma-

nipulator, giving the operator a feel for what was happening. A micro-
phone located on the pump was connected to a speaker at the sampler so
that sounds in the pump could be heard. Many attempts were made to re-
‘cover the missing capsules. Once when the magnet was retrieved, the top
of the first capsule was recovered: Based on feel and sound the second
capsule could be lifted a few inches in the pump bowl but was not re-
covered.®” It .is believed to have moved'bgtween the mist shiéld.and.the
guide cage, preventing retrieval. A mockup.showing this situation with
a magnet inserted is shown in Fig. 4.

Drive Unit

The latch attached to the end of the drive unit cable operatéd satis~-
factorily for about-a year. It then started binding in the lower bend
of the transfer tube. A new latch with a smaller diameter was installed.
Later this latch was replaced with another one of similar dimensions,
" which was fabricated of 430 stainless steel instead of 304 stainless:
steel so that it was magnetic. The drive unit assembly is shown in
Fig. 5.
| One of the bevel gears connecting the cable drive unit to its motor
started slipping on its shaft in December 1968 after 15 months of use.
The gear was secured to the shaft by two set screws, but the repeated
stress placed on the unit while attaching the capsule and checking it
probably loosened the screws and caused the gear to slip on the shaft.
Also,sjust prior‘fo this difficulty, a key'had jammed in the latch. Extra
strain was applied to the drive unit while trying to remove the key from
the latch with the manipulator.. Slippihg was first,noticed while at- ‘
tempting to free the key. ' ! '

To repair the gearing, the 1C assembly was lifted above the top of
3A. This required draining the reactor and removing two top shielding

C
 

 

 

15

ii.,i R el - PHOTO 92581

- n

 

»

Fig. 4. Mock-up Fuel Pump”Bcwl'Section Showing Dropped Capsules and

~v ' Magnet.
 

 

 

 

 

 

 

 

 

 

16

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fig. 5.

Drive Unit Assenbly.

1
3

 

 
 

 

 

17

blocks to reach the bolts of the flange located at the lower end of 1C.
Next, a 3-in.-diam hole was drilled through the 1/2-in.-thick wall of the
drive unit box at a point adjacent to the gears. When the motor was

operated, the gear on the drive unit was observed to slip on its shaft.

‘Using a long-handled wrench, both set screws were tightened, but the gear

still slipped. It was then welded to the shaft. Both set screws on the
mating gear on the motor shaft were tightened and locking screws were in-
stalled to hold them in place. A plug was then welded over the hole in
the containment box. At the ‘start of this repair operation the radiation
level at the gears was 45 R/hr. At the outside of the containment box

‘where the hole was drilled it was 27 R/hr.

Limit switches for the drive unit motor were actuated by a nut

moving along a ‘threaded shaft.“‘When the gearing slipped,‘the motor was

-~ operated in the withdraw direction too far allowing the nut to become dis-

engaged from the threads on the shaft. When the motor direction was re-

Versed,‘the nut failed to engage the threads again. As a result of this,
the upper and lower limit switches and the 4-in, permissive switch for the

a'operational and maintenance valves were bypassed for the remaining life of

the drive unit.
~ Standard gears were used in the drive unit assembly. The design

clearances for these gears'resulted'in a hysteresis'in the position indi-

cator readings. 'The'inch'hand-reading-variedvabout'l/Z'in. from insertion
to withdrawal direction. ' The foot indicator varied 3/4 ft so that the

. operator had to mentally compensate for the differences to be certain of
_the exact location of the capsule. All positions specified in instruc-

_ticns referred to the inserting mode.

~ For obtaining some special ‘types of samples, the distance from the

latch stop to the salt surface in the pump bowl had -to be known accurately
- 'so that the capsule could be stopped at a specified distance from the salt
surface. The position indicator ‘distance readings were reproducible to

<1/4 in. Thus thevcapsules_could be accurately positioned during sampling.

On at least five‘occasions'the.latch and capsule;assembly failed to

V'go down the transfer tuhe\propefly. It Stopped;invthe.loWer'part of 1C

or in one of the gate valves at the exit of 1C.  When this happened, the
 

18

drive unit cable coiled up in lC-forming kinks which prevented it from

| withdrawing properly. As initially installed there was no way of telling
when the latch failed to move into the transfer tube. Only when the po-
sition indicator hands moved unevenly during the withdrawal was a mal-
function indicated. |

The first time this happened the loops that formed in the cable were
untangled by repeated short insertions and withdrawals. After all of the
cable was successfully withdrawn and the operational and maintenance
- valves were closed, the cable was extended.into 3A for visual examination.
Two bends were found and straightened.

On two other occasions.the position indicator hands did not operate
smoothly and no sample was obtained. No damage was found to the cable
and no definite reason for hanging was discovered. It was possible,
however, for the capsule to be retained in either of the openings between
the two seals for the gate in the valves. -

The fourth time the latch hung, a kink in the cable jammed in the
narrow passage that connected the access port area and the drive unit box
stalling the drive motor so that it would not operate in either direction.
In an effort to untangle the unit without draining the reactor the opera-
tional and maintenance valves were carefully closed by hand so that the
access port could be opened for visual examination of the cable. When
the operator pulled the cable from 1C into 3A with the manipulator, the
latch and capsule were missing. The operational valve had sheared the
cable when it was closed.” Calculations made later indicated that an
8-1b force on the hand wheel of the valve was sufficient to shear the
cable. The latch dropped through the transfer tube and rested on the.
latch stop. The sudden stop snapped the wire rope holding the capsule
‘allowing it to fall to the bottom of the pump bowl.‘°""!The,1atch was
retrieved during a four-week maintenance effort. Figure 6 shows the re-
covery tooling and containment. Figure 7 shows the latch and key after
. removal from transfer line. One unsuccessful attempt was made to recover
the capsule. A new 1C assembly including a new drive unit was installed.

The fifth time the drive unit malfunctioned no attempt was made to
close the operational valve as we did not want to chance cutting the

cable again. The reactor was drained so that the access port could be
19

PHOTO 88999

.

 

 

 

 

 

’

 

 
 

 

o
o
2
@K
O
2
Ry

ne.

Li

 

20

 

 

 

Latch and Key After Removal from Transfer

 

 

 

Fig. T

 

 
 
 
 
 
  
 
 
 
 
 
 
 

 

(LU

21

opened to observe the condition of the cable. This was the first oppor-

tunity for a visual inspection of this type of trouble. The capsule was

seen lying on its side on the lower ledge of the access port opening. The
latch was above and behind'it. The cable formed many coils. The normal
position of the capsule when attached to the latch was about four inches

below the place where it,was,observed. No explanation was found for its

‘observed location. While“attempting to grasp the capsule with the manipu-

lator, the operator brushéd;against one of the coils of cable shifting the
position of all parts. ;Theflatch fell on itstide allowing the key to
slip out of it and theacapsnle'to drop into the pump bowl.'? The capsule
recovery attempt with.magnets-was described in a prior section.

While the reactor was drained a proximity switch, shown in Fig. 8,

~ was mounted on the transfer tube between the maintenance valve and the

floor of the containment boi; This unit-could detect the novement of the

magnetic latch past this pOintgrthus indicating that the capsule and latch

~had indeed entered the transfer ‘tube. This switch was obtained immediate-

ly after the fourth hangup occurred and was awaiting a reactor shutdown
for installation when the“fifth hangnp occurred. Several malfunctions
were detected by the switch and were corrected before difficulties

occurred.,

Manipulator

The manipulator (Fig;gQ);required more maintenance than any other

_compOnent_of the samplerfenricher.: The two=-ply polyurethane boots which
 sealed the arm to thehwall*of 3A had to be replaced 17 times or an average
of 3-1/2 times a year} After ‘standard maintenance procedures were estab-

--:ilished the estimated cost per change was $1,800,1°

During deSign the plastic boots were recognized as a potentially weak

'member that might rupture_under_the 40-p51 design pressure conditions.
';Therefore, a cover wasakept:over the operator end. of the'arm except during
: periods when the manipulator was in use, The cono-seal'flange that sealed

‘the cover to area 3A was-: easy to- open, but awkward to close because of the

crowded conditions around the flange location.
 

     

 

 

 

¢c

 

 

 

 

 
  

. i,

%

 

PHOTO 85405

 

 

 

 

   

 

 

 

’ -

 
 

 

 

24

Improvements in boot design were made throughout the operating
period. The first major modification was the addition of steel tings1to
the convolutions of the inner boot. This prevented the boot from col-
lapsing against the arm when there was a pressure differential across the
boot with the higher pressure in 3A. When the boot collapsed movement

of the arm abraded and pinched the plastlc.. Also, frlctlon made the in-
tand~out movement of the manipulator difficult.

When the d1fferential pressure was in the opp031te dlrectlon, two
problems arose from:the ballooning of the boots. Some of the steel rings
"in the inner'boot_siipped out of the copvoluations. The displaced rings
- pinched holes in the boot after a period of use. During early sampling
cjcles prior to operating'the reactor at power, the pressure differefitial
blew the boots off their flange on 3A. Improved clamping arrangements
orevented this from recurring. Also, a differential pfessure switch was -
installed to'protect against excessive pressure differentials in the di-
rection that caused ballooning. :,

Different thicknesses of the polyurethane plastic were tried. Ease
of manipulationivaried inversely with the ghickness;‘ However, failures
occurred more frequently with thin—fialledlmaterial.'iTherefore, the
heavier-walled material was used tofreduce maintenance requirements.

The polyurethane yellowed with time in the high-radiation field that
occurred in 3A. Light was absorbed by the dark surface, resulting in a
low level of illumination inside the equipment. To counterbalance this
effect, the outer boot was spray-coated with a white plastic (Haplon) that
did not yellow and which also increased the strength of the material.
Radiation level inside 3A was >100 R/hr.

Three other types of failure occurred. After installation of the
rings, the rough surfaces on the rings punctured the boot when excessive
pressure occurred in area 3A. After this, weld joints were filed smooth.
Once the outer boot was snagged on the lower part of the transport con-
tainer, tearing the boot. The third type of failure resulted from air-
borne particles that were embedded in the plastic during fabrication at
the manipulator shop. These particles loosened with continued use leaving
pin-holes through the wall. Visual examination of each new boot prior to

installation reduced this type of failure.
 

 

 

 

25

| The manipulator hand contained eight pinned joints. When the hand
was assembled, the joint clearances were small (0.001 to 0.003 in.). The
fingers were adjusted to close tightly. After use, the joints loosened
so that the fingers did not touch over part of their length. Also on a

few occasions the arm and hand were used to apply much more pressure than

.normally needed, which bent the fingers and the arm. A bent arm would

not slide through the bearing in the shield plug freely.

Operational and Maintenance'Valves

The Stellite-faced gates of the operation and maintenance valves
were lapped until they fitted against the Stellite—faced seats located
on each side. Before 1nstallation in the sampler, the leak rate from the
buffer zone across both seals was <1 cc/min at 40 psi pressure differ-
ential for each valve. _During,use a small amount of foreign'naterial ac-~
cumulated on the upper face (see Fig. 10) of the gates, increasing the
leak rate. After the first fun and before power operation, the gates
were cleaned by wiping them with a damp cloth. The leak rate then de-
creased to less than'l'cc/min again, but gradually increased with use as

dirt-particles accumulated"again. After power operation, the high-

, radiation level prevented recleaning. Initial plans called for the use

of only the operational valve during normal operations, with the mainte-

nance valve as a backup in case the operational valve failed and for use

during periods of maintenance on other components of the sampler. Both
valves were used routinely as an added precaution against the accidental
release of gaseous activity from the pump bowl. o |

Special ring-joint spring-clamp disconnects‘“ developed at ORNL for

'”remote maintenance usage were chosen for the valves. Figure 11 shows the

-ioperational valve with the flanges and ‘a pair of spring clamps For. this

application each flange half was fabricated individually using a set of

- master gages as guides instead of the prev1ously used method of machining
“two halves to match each other. The change was necessary to permit re-

‘placement of components. - When the new 1C assembly was installed a new

flange half was mated with a used one for the first time.; A leaktight

(<10~* cc He/sec) joint was obtained.
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

26

 

PHOTO 80574

 

 

 

 

 

 

 

 

 

 

Fig. 10. Dirt on Gate of the Operational Valve. .

¢

 

"W
  

 

    

 

. .- ’

 

 

 

PHOTO 68481

 

 

 

L2

 

 

 

 

 

 

 

 

 

 

 

 

Fig. 11. Operational Valve Assembly.
 

 

28

Access Port

Six pneumatically controlled Knu-Vise clamps were used to close and
seal the access port. This required three clamps'to be activated at one
time to close the port and the other three to move 15 seconds léter‘to
seal its opposite side. The piston rod of the activating cylinders did
not always move freely through its elastomer O-ring. Some types of lubri-
cation applied to the seals did not function as well in the dry helium
atmosphere as in air. Friction sometimes caused failure of one or more
of the Knu-Vises to lock in the closed position or to open. 1In either
case the manipulator was used to help the clamp to move., A knob added to
the locking link provided a gripping surface for the manipulator.

Figure 12 shows a 1C assembly. 7

“When 1C was pressure checked at 48'psig after installatiofi, the load
on each clamp was about 270 pounds. For the configuration used, the
clamps were rated for a load of about 300 pounds. The loading that oc-
curred during pressure testing loosened the link pins slightly and reduced
the pressure exerted on the gasket, thus increasing the leak rate through
the seals. Prior to installation of the 1C assembly, the access port leak
rate was less than 1 cc/min at 40 psi differential. After use, it in-
creased by more than a factor of ten. |

The hinge pins for the access port were held in place by a cottér
key through a hole in either end of the pin. The top key of the lower
pin fell out allowing the pin to drop free of the upper part of the spring-
loaded hinge. Using only the manipulator the hinge was reassembled. Then
a new cotter key was inserted through the 0.100-in.-diam hole in the pin
and was bent to lock it in place.

On the second area 1C assembly, the Knu-Vise clamps were modified so
that they could be semi-remotely adjusted to increase the pressure on the
gasket while installed. However, the radiation level in 3A was so high
(more than 100 R/hr at the manipulator port) that very little adjusting
was done. | |

During one sampler-enricher maintenance period when the access port,
the operational valve, and the maintenance valve were all open with the

reactor at 1/2-psig pressure, a small quantity of radioactive gas was
 

 

 

 

 

 

29

 

 

Fig. 12. 1C Assembly with Access

 

PHOTO 88903
.

 

 

 

 

Port Closed.

 
 

 

30

O

released to the building ventilation system. The gas leaked past the
O-ring seal on one of the Knu-Vise cylinder rods. After this incident, a
small charcoal trap was installed in the vent line from the cylinders and -
a valve in the line was 1eft closed except during use of the access port.

No further releases were detected. .

Removal Valve

The Teflon body and stem seals in the ball valve (removal valve) lo-
cated above 3A showed little or no detectable radiation damage. Some
leakage from the buffer zone to the atmospheric side of the valve resulted
when particles on top of the ball caught on the seals when the ball was
rotated. Pressure on the body seals was adjusted several times without
removing the valve from the system. Also, the upper seal was replaced
once. |

The mounting bracket for the air cylinder operator was not sturdy
enough to prevent movementvof the cylinder on the valve body which limited
thé maximum torque that could be applied to the ball by the cylinder.
However, the crowded conditions in this region prevénted tightening the
bracket bolts without removing several components. A top view of this
area is shown in Fig. 13. | |

When purchased, there were no position indicator switches on the
valve assembly to show when the valve was opened or closed. Switches and
an activating arm were subsequently installéd. These worked satisfac-
torily until one switch failed. There was-inéufficient clearance for
replacement without removing the valve assembly. This would have re-
quired at least two days. The other switch became inoperative later. The
valve was then used with buffer gas pressure as an indication of whether

the valve was open or closed.

Removal Seal

The removal seal, located above the removal valve, was successful in
preventing the release of a measurable quantity of radioactive gas to the
atmosphere when the transport container was being inserted or removed from

3A. It also prevented water vapor and oxygen from entering 3A. The i T
 

et a3 i gk

 

|

 

 

 

 

 

 

 

Top View Showing Removal Valve Area.

PHOTO 81698

 

W
s
 

32

transport container was lubricated with silicon vacuum grease to reduce
O-ring friction, but this increased the particulate contamination problems.
Only one replacement of the O-rings and nylon guide was required to reduce
the spread of'particulate contamination. This was done whilé,berforming

other maintenance work on the removal valve.

 

Lighting and Viewing

The_iOOfwatt light bulb failed only one time and was replaced one
other time. Replacement was possible without opening 3A to atmosphere
but did require removing two pieces of shielding.

The Plexiglas lens at the illuminator port was shaped to refiect a
beam of light on the latch assembly when the access port was open. The
4-in.-long plug had to be changed several times because of radiation-
induced darkening. The 1/2-in,-thick port at the periscope was only
changed once. It did not turn yellow as rapidly as the thicker illumi-

nator port lens.

Vacuum Pumps

Two vacfium pumps (Cono-Hyvac) were used in the offfgas system. The
discharge of one pump which was exposed to helium containing gaseous fis-
sion products was connected to the auxiliary charcoal bed. The shaft
seal in this pump was improperly installed as received and had to be re-
placed after a few months of operation. The belt was also replaced once.
Just a few months prior to shutdown, the unit was replaced rather than
repaired because of the radiation level and contamination associated with
it. No fadiation damage was apparent to the oil. Because of space limi-
tation the oil level in the pump was hard to determine. Once the pump
failed to operate properly because the oil level was too low. O0il was
added_several times. Figure 14 shows the two pumps. The one on the

right was the one exposed to contamination.

Electric Penetrations and Wiring

Several difficulties were encountered with the electrical penetra-
tions and the wiring. Four- and eight-pin receptacles (Physical Sciences

Corp.) were used for electrical penetrations of the containment wvessels.
 

 

 

 

 

 

 

 

 

 

 

PHOTO 69408

33

 

Hot Vacuum Pump (Right) Cold Vacuum Pump (Left).

Fig. 1h.
 

34

Once three wires on a receptacle came loose from their pins. After recon- =
necting the wires, epoxy resin was poured around the assembly to strengthen
the connection and to increase the electrical insulation between adjacent -
leads. This was done at all electrical penetrations. | .

On another occasion the motor'jumper cable between the 3Alpenetration
and 1C penetration grounded to the metal walls inside 3A. A hdle was
drilled through the 3A cover plate at a location above the receptacle in
1C for these fiireé. The grounded wire group was unplugged from the iC
penetration and a new jumper cable was installed from a pipe cap containing
a new penetration to the 1C receptable, bypassing the damaged wiring.

While the cap was being welded to the 3A cover plate, the welding
machine was connected to a building ground. A stray current passed through
an adjacent receptacle blowing all eight pins out of it.. The damaged piece
was removed. The wire bundle was recovered from the floor of 3A and at-
tached to a new unit. Then the new receptacle was wélded in place, being
sure this time that the welding machine was grounded close to the point of

welding.

Instrumentation

 

Special soft-seated solenoid valves were used which had low-leak rates
through the seats even with a 40-psi pressure gradient on either side of
the valve. The 1/2-in. valves used in the off-gas system gave trouble
mainly from foreign particles (metal chips) becoming embedded in the seat
after installation. This occurred during the initial period of operation.
Near the end of the operation the leak rates étarted increasing in sev-
eral valves probably from radiation damage (hardening) to the plastic
seats. Several coil failures occurred on the 1/4-in. valves. These
could be replaced without removing the valves.

Commercial-grade 3—way-sdlenoid valves were fised in the gas lines to
the access port gas cylinders. These had a much higher failure faté:than
the special valves but were easily replaced. Failure presented no haiard,
only inconvenience. - | . )

The strain-gage type pressure transducers gave satisfactory service.

The one in the removal valve buffer pressure system was located near the { T
 

35

illuminator. It was temperature sensitive so that the output shifted when
the power to the light bulb was varied, since this changed the temperature
of the transducer. Thermal insulation was placed around the instrument to

reduce temperature variations.

Summarz

The sampler-enricher wasrused to isolate routine and special salt and
gas samples, to make minorvchanges'in.the-salt‘chemistry, to perform
special tests in the pump bowl to add enriching salt during periods of
full power operation, ‘and was designed to add poison to the fuel under
emergency conditions, The equipment was used by the reactor operating
crew, not specialized operators.- All sampling and maintenance activities
were performed without the release of gaseous or particulate activity that
exceeded laboratory safety limits. No person received an excessive dose

of radiation from activities associated with the equipment even though

' radiation levels in51de the equipment were high (<100 R/hr).

Necessary maintenance work on the equipment was performed. The ma-
nipulator boots and the capsule drive unit‘required the most attention,
part of which could be attributedrto the use by. many different operators
instead of a special crew, Work on the drive unit required a reactor
shutdown to meet containment criteria. All other’maintenance could be

performed with the reactor operating. When the reactor was deactivated,

the equipment ‘was in operating condition.
 

 

10.

11.

12.

13.

14.

36

References

R. C. Robertson, MSRE Design and Operations Report, Part I, Descrip~
tion of Reactor Design, USAEC Report ORNL-TM-728, p. 141, Oak Ridge
National Laboratory, January 1965.

R. B. Gallaher, MSRE Sampler-Enricher System Proposal, USAEC Report
ORNL-CF-61-5-120, Oak Ridge National Laboratory, May 24, 1961.

R. C. Robertson, MSRE Design and Operations Report, Part I, Descrip-
tion of Reactor Design, USAEC Report ORNL-TM-728, pp. 244274, Oak

‘Ridge National Laboratory, January 1965.

J. R. Tallackson, MSRE Design and Operations Report Part II A,
Nuclear and Process Instrumentation, USAEC Report ORNL-TM-729,
Oak Ridge National Laboratory, February 1968.

- J. R. Tallackson, MSRE Design and Operations Report, Part II B (to
be published).

MSR Program Semiann. Progr. Rept. Aug. 31, 1968 ORNL-4344,

pP. 311-317.

MSR Program Semiann. Progr. Rept. Aug. 31, 1969 0RNL—4449
PP. 245-246. .

R. B. Gallaher, Recovery of Capsule from Sampler-Enricher, 1nternal
memorandum MSR-66-24, July 18, 1966.

MSRE Staff, ' MSRE Sampler-Enricher, An Account of Recent Difficulties
and Remedial Action, internal memorandum, MSR-67-73, Sept 8, 1967.

R. W. Derby to M. W. Rosenthal and B. L. Greenstreet, Separation of
Sample Cable and Capsule, Sept. 6, 1967.

R. W. Derby to M. W. Rosenthal and B. L. Greenstreet, Test of Sample
Cable, Sept. 11, 1967.

P. N. Haubenreich and MSRE Staff, An Account of Difficulties with
the Sampler-Enricher that Led to a Second Capsule Being Left in the
Pump Bowl, internal memorandum, MSR-68-125, Sept. 3, 1968.

Private communication with M. Richardson,-May 26, 1970.

P. P. Holz, Ring—Jcint Spring-Clamp Disconnect, ORNL-CR-61-7-92,
Oak Ridge National Laboratory, July 14, 1961. ’
 

 

 

1.
2,
3.
4.
5.
6.

8.

9.
10.

11,

12,
13.

14,

15.
16.
17.
18.

19.

20
21,
22.
23.
24.
25.
26.
27.
28-32,

33.
34,

35,
36.
37.

380'

J.
R.
C.
S.
M.
E.

D.

F.
R.

_E.

C.
G.

R..
E.

D.
W.
J.
F.
J.

S.

W.
J.

D.

L.
A,
J.
c.
R.
W.
A.
R.

P,
H,

L.
F.
F.
E.

37

ORNL-TM-3524

" Internal Distribution"

Anderson
Apple
Baes
Beall

Bender

S.
S.
F.

J.

E.

B.
L.
F.
B.
L.

L.

R.

Jl'
P,
R.

E.
M.
P.
H.
H.
B.
R.
G.
H.

H.

N.
W.

Bettis
Billington

Blankenship
Blumberg
G.

Bohlmann .
Borkowski
Boyd
Briggs
Compere
Cope, AEC-0SR
Cottrell
Crowley
Culler
Distefano
Ditto o
Eatherly

Engel

Ferguson .
Ferris
Fraas
Frye
Gabbard
Gallaher
Grimes
Grindell
Guymon -
Harley
Haubenreich -

Hoffman

74=75.
76.

77-79.
80.

39,

40.
41.
42,
43.
44,
45.
46.

47.

48,
) 49-
~ 50.

51.

52,
53.
54.
55.
56.
57.

58-59.

60.
61.
62.
63.
64,
65.
66.
67.
68.

69.

70.

71-‘

72,
73-

,A. Ml
-M-‘ ‘Jo
. Dunlap Scott

W. H. Jordan

P. R. Kasten

M. T. Kelley

J. J. Keyes

S. S. Kirslis
A. TI. Krakoviak

~ Kermit Laughon, AEC-0SR
- M. I. Lundin

R. N.
H. G.
R. E.
H. E.
H. C.
L. E.
A. S.
A. J.
R. L.
E. L.

Lyon
MacPherson
MacPherson
McCoy
"McCurdy
McNeese
Meyer
Miller
Moore
Nicholson
Perry ‘
Rosenthal

M, R. Sheldon
M. J. Skinner
I, Spiewak

D. A. Sundberg
R. E. Thoma

D. B, Trauger
G. M. Watson
A. M. Weinberg
J. R. Weir

M. E. Whatley
J., C. White

G. D. Whitman
Gale Young

Centra1 3esearch Libfary

Y~12 Document Reference Section
Laboratory Records Department

‘Laboratory Records (RC)
 

81.
82.
83-84.
85.
86.
87'
88-89.
90.
91-93.
94-95.
96-100.

101.
102,

38

External Distribution

David Elias, AEC, Washington, D. C. 20545

R. Jones, AEC, Washington, D. C. 20545

T. W. McIntosh, AEC, Washington, D. C. 20545

H. M. Roth, AEC-ORO, Oak Ridge, TN 37830

M. Shaw, AEC, Washington, D. C. 20545

W. L. Smalley, AEC-ORO, Oak Ridge, TN 37830

Division of Technical Information Extension (DTIE)

Laboratory and University Division, ORO '

Director of Division of Reactor Licensing, Washington, D. C. 20545

Director of Division of Reactor Standards, Washington, D. C. 20545

Executive Secretary, Advisory Committee on Reactor Safeguards,
Washington, D, C. 20545 :

A. Houtzeel, TNO, 176 Second Ave., Waltham, Mass. 02154 .

R. C. Steffy, Jr., TVA, 303 Power Building Chattanooga, TN 37401