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MICROCOPY RESOLUTION TEST CHART
NATIONAL BUREAU OF STANDARDS - 1963
cini prate
. 2196
conf.660524-3
20 $2.00: MNSO
JUN 27:.
..corne
.
MASTER
.
.
The Impact of Kllorod Operational Experience on The
Design of Fabrication Plants for 2334-Th Fuels*
... ...
R. E. Brooksbank
J. P. Nichols
A. L. Lotts

RELEASED FOR ANNOUNCEMENT
IN NUCLEAR SCIERCE ABSTRACTS
3
+
.
-
-
*
For presentation at the "Second International Thorium Fuel
Cycle Sympusium," Gatlinburg, Tennessee, May 3-6, 1966.
..
.
.?
in
LEGAL NOTICE
This report me prepared us as account of Government spor ored work. Nelibor the valued
dutos, por the Commission, nor day Srso acting on bebalinithe Commission:
A. Makes cay Mitut ur representation, expressed or iviplied, with respect to the accu-
racy, completeness, or usefulness of the Information contained to Wis report, or that the use
of way information, e puntu, method, or process disclosed Louis repost way dot infringe
privately owned ricato; or
B. ASRIRAs way Habilities with respect to the une of, or ler dumugo resulting from the
un of Lay Information, apparitu, melbod, or provou diaclosed la taula report,
As wred in the abovo, "persoa acttag oo baball of the Commissioo" Locladas nay em.
ploys or coatructor of the Commission, or employee of such cootractor, to the oxteat Want
such employs or coatructor of the Commission, or omplogue of much contractor properts,
disumiastes, or provides ucco to, by 'aformation pursuant to his employment or contract
with the Commission, or wo employment with such contractor,
.........
Research sponsored by the U. S. Atomic Energy Commission under contract
with the Union Carbide Corporation.
The Impact of Kilorod Operationa). Experience on The
Design of Fabrication Plants for 238U-Th Fuele
R. E. Brooksbank, 4. L. Lotts, J. P. Nichols
1.0 introduction
The development of reactor systems that would employ thorium as a
reactor fuel has created a basic need for solving the problems of the
Thu-Su fuel cycle. The major problem of this cycle is the radiation
levels encountered in fuel reconstitution.
The first pilot-scale demon-
.
stration involving this cycle was the Kilorod Program, successfully
.
.
.
completed during 1964. This program was aimed at advancing the technology
:
-
*
by coupling the ORNL sol-gel process to the vibratory compaction method
.
*
of fuel fabrication by semi-remote methods on a 10 kg/day scale.
.
The requirement of the Brookhaven National Laboratory for 1100
-
Zircaloy-clad fuel elements containing 3% DUO, -.97% Thon, afforded the
opportunity to provide engineering data under sustained operating condi-
tions. In the Kilorod case, specific records were maintained on equipment
-
".
..
i
ni
reliability, process performance, radiation levels and exposures, manpower
effectiveness and product acceptability. This paper is an attempt to
evaluate several of these factors as they apply to plant scaleup. Because
of the importance of the radiation information on the economics and safety
of the fuel cycle, considerable emphasis is placed on the radiation data
obtained during the program.
The results of the pilot plant program were highiy encouraging as
approximately one metric ton of product was produced during an eight-month
>
>
.
.
..
.
.........
.
......
...
.
.....
.. din..
'
.
.
*
*
*
*
operating period. Product specifications were met in each process phase
resulting in a final product which was chemically sound and was compacteå
to 90 per cent of the theoretical density. Process losses and recycle
2
* 2
*
rates were acceptable.
-.
2.0 Process and Facility Description
Å detailed description of the entire Kilorod Facility has been given
previously, however for completeness, a brief description of a generalized
flowsheet is necessary (Fig. 1.). Basically, the flowsheet may be divided
into three separate process phases. The first phase consists of the prepa-
ration of feed materials which included the hydrothermal denitration of
thorium nitrate tetrahydrate and the removal of the ionic contamination
and daughter products of 2324 from the 2330 by solvent extraction. The
sol-gel process was then used in the second phase to combine these raw
materials into a dense, homogeneous mixture of 3% 43-4002-97% Thoz.
Finally in the last phase, rod fabrication steps were accomplished by
preparing the solids into the desired size fractions and compacting these
solids into 0.5-in. Zircaloy tubing. The rods were then welded, cleaned,
inspected and shipped.
The solvent ex':raction facility was operated remotely k hinä 5-ft
of concrete chielding using standard pulse column technology. Because
this technology is well established, a detailed description will not be
given in this discussion. The only new aspect of the purification system
was the use of a new extractant, di-sec butyl phengl phosphonate, which
performed adequately.
1
THORIUM
NITRATE®
UNCLASSIFIED
ORNL-Dwg. 63-6210
R-2
HYDROTHERMAL
DENITRATOR
ALT
I NIAI Art an
Mind
SOL-GEL
PROCESS
FUEL ROD
FABRICATION
AGED
.
233 0
..."..
...
3

Someone ..
FUEL,
.RODS ..
::
min
2330 SOLVENT
EXTRACTION
-
VO2(NO3)2
FEED
SOLUTION
FUEL ROD
.
.:..
La 2323 DECAY PRODUCTS
.::· CARRIER
:
Fig. 1
.
KILOROD FACILITY FLOWSHEET
.
.
The "heart" or the Kllorod Facility was the shielded enclosure con-
structed in a former reprocessing cell (Fig. 2). The outer cell wall,
measuring 20-ft-long x 19-ft-wide x 27-ft-high served as a secondary
barrier in the event, of an activity release. The sol-gel cubicle is
located on the upper level. The mixed oxide particles resulting from
this process phase were then size reduced, weighed and blended in the
UNCLASSIFIED
ORNI Dwa 6aans
powder preparation shaft. The vibratory compaction, welding, cleaning
and inspection functions were performed in cubicles on the lower level.
The second level serves as a decontamination area for equipment repair,
All of the operations were conducted through 4.5-in. of steel or 8-in.
of high density concrete using gloved hands or castle-type manipulators.
An alpha tight steel membrane lineà each of the process cubicles,
3.0 Process Evaluation
Necessary to the evaluation of any new pilot-scale process is an
abundance of data which may be used for subsequent scaleup. In this
regard, the Kilorod results have indicated that the sol-gel rou-
fabrication fuel recycle scheme is a workable system and adaptable to
remote operation.
An overall program summary, presented in Table I, gives some of the
major results obtained from the various phases of the operation.
In the feed preparation steps, 1277 kg of Tho, and 50 kg of
su
was produced with product losses that are acceptable. The utilization
of the material made in these steps, which is a measure of product repro-
ducibility, was greater than 99 per cent. On-stream time for each of
these phases was 100%.
.
*
.
UNCLASSIFIED
ORNL DwQ 64-405
PERSONNEL SHIELD
4-1/2-in. STEEL
france
SOL-GEL
OXIDE
LEVEL
.
D
41
.
..
CELL WALL
5ft CONCRETE
8-1/2-in. BARYTES.
CONCRETE
PRIMARY
- CONTAINMENT
(SEALED)
SECOND LEVEL
EQUIPMENT
MAINTENANCE
POWDER
CONDITIONING
SHAFT
- SERVICING PORTS
FIRST LEVEL
ROD FABRICATION:
ATORY COMPACTION
WELDING
CLEANING
INSPECTION
Fig. 2
KILOROD FACILITY
Cisivi icoon birinin

Cisiti incong birinci

Table i
KILOROD PROGRAM RESULT SUMMARY
LOSSES OR ON-STREAM
RECYCLE. TIME
(%)
(%)
MATERIAL | MATERIAL
OPERATIONAL PROCESSED UTILIZATION
PHASE
(kg)
(%)
ThO2 PREPARATION : 1277 99.0
233U PURIFICATION .50
100.0
100
100
1.0
0.1 .
0.1
0.3–(7.6)
90
SOL-GEL PROCESS
994
99.8
ROD FABRICATION · 980
94.3
a. RECYCLE INCLUDES STARTUP PHASE.
11.6)
80
-
Within the sol-gel proce88, 994 kg 07 the mixed oxides were prepared.
In addition to this quantity, 124 kg of oxide containing depleted urenlum
was used during the shakedown operation. Process losses for the operating
period averaged 0.1 per cent. Small repairs could be made within the
cubicle without process interruptions. Major repairs, such as calciner
element replacements, required a complete cleanout and shutdown. During
the program, three element replacements were required which decreased the
on-stream time of the process to GC per cent.
In general, the rod fabrication items were standard mechanical
devices which were adapted to operate in a hostile environment. At the
onset, considerable difficulty was experienced with a ball mill which
resulted in some down time, effectively reducing the on-stream efficiency
to 80 per cent. This value is still good for directly maintained radio-
chemical equipment operation. In all, 980 kg of oxide was compacted into
1100 fuel tubes with process losses which totalled 0.3 per cent. The
recycle rate was approxtmately 7.6 per cent for the cverall program and this
includes the startup period. This recycle is the result of "soft" density
spots located in the fuel colum as determined by gamma scanning. The
recycle rate was reduced as the cperators gained experience. This system
demonstrated a peak production rate of 15.5 rods/8-hour day.
3.1 Product Acceptability
Another major item necessary for new process evaluation is the accept-
ability of process product.
The tailend product resulting from the Kilorod
operation and the material from each phase of the program met the assigned
specifications (Table 2).
ORNL Dwg 66-1674
Table 2
PRODUCT ACCEPTABILITY
OPERATIONAL
PHASE
SPECIFICATION PRODUCT
> 100
279
> 103
3.5 x 103
233U PURIFICATION
GROSS y D. F.
Th D. F.
233U RECOVERY
NO3/U
%)
> 99
99.4
< 2.5
2.2
8

U/ Th+U (%)
3.0 + 0.05
3.01
SOL-GEL
<0.05
0.03
GAS OXIDE
RELEASE
(cc/gm) CRUSHED OXIDE
< 0.3
0.18
FUEL BED HEIGHT (in)
_11
DENSITY
VARIATION
+ 2
+ 2
ROD TO ROD
WITHIN ROD
ROD FABRICATION
(%)
12
+ 2
PACKED DENSITY (g/cc)
9.0
8.97
LOADING (grams)
900
906
-
-
.
The specifications for denitrated Tho, were met in all but two 13 kg
batches which were made during the startup phase of the program. Because
the preparation of this feed material has been reported elsewhere, it will
not be covered in this discussion.
The major specification for the purified uranyl-nitrate 18 the NO 3
ratio which must be kept below 2.5. The overal.l value for this ratio was
rnaintained during the nine solvent extraction runs. Other specifications,
including decontamination from thorium and y activity were also met.
Uranium recovery was greater than 99 per cent in each case.
Product specifications were met with the material being discharged
from the sol-gel cubicle. The major criteria was the presence of 3.0 +
.05% uran" um in the oxide.
In the operation, an average value of 3.01
was obtained over all of the batches prepared. Other requirements of BNL
included a product gas release value of 0.05 cc/gm for the freshly pre-
vareà oxide and 0.3 cc/gm for the crushed material. Both specifications
were met.
Stringent requirements were placed on the fuel roi.
These require-
ments specified the bed height to be within 42 l-il.. with a rod-to-rod
fuel column density of +2%. Aiaverage packed bed density of 89.7% was
demonstrated for all of the fuel elements prepared.
4.0
Radiation Data
Because of the importance of the radiation data on the economics and
safety of the thorium furl cycle, detailed records were maintained on
operator exposures, cubicle backgrounds and the effect of cleanup.
Table 3 summarizes some of the pertinent exposure data obtained in

-
233u, kg
RADIATION EXPERIENCE 0 232–23 U PROCESSING OPERATIONS
IN GLOVE GOX L!HES
SAVANNAH RIVER
KILORODO I | Ib | | |B & wC
uoz - ThO2, kg
1000 - 1 - 1 - 82
30 | 43 59 53 2.5
232 U CONTENT, ppm
38 240 240 4 42
POST PURIFICATION TIME, days
20 3.75 3.75 70 60
NUMBER OF OPERATORS
5.5 3 3.1 3. 8
AVERAGE DOSE RATE, mrem/man-week 19.2 2000 1400 300d 67
DOSE PER kg 233U PROCESSED, mremíkg 2334 127 | 155 76 120 350
DOSE FROM FRESH MATERIAL, % 1 20 80 80 33 100
a. SHIELDED BY 4.5-in. STEEL.
b. SHIELDED BY 0.5-in. LEAD.
C. "THE B & W RECYCLE FABRICATION PROGRAM FOR 238U, Dec. 15, 1965.
THESE EXPOSURE RATES ERE PRE-PLANNED FOR SHORT-TERM
OPERATION. INDIVIDUAL DOSES DID NOT EXCEE) THE ALLOWA LE
CARTERLY DOSURE
L
il:
j.
.i
.-.-.-
E
.
¿
-
2
.
.
-
.
-
.
.
.
-
-
-
-
-
--
-
-
-
-
.
.
-
.
........
.
.-
-
.
7
= 2
the Kllorod Program and also data from a sul-gel operation at Babcock and
Wilcox and a U20g preparation operation at Savannah River.
In this program 2334 solution (containing 38 ppm 320), purified by
ACT
solvent extraction and approximately 5 days old, wes furnished to the
Kilorod Facility at about 40-day intervals. In each of these intervals
(called "campaigns") the post-purification time in sol-gel processing
veried from about 5 days to 25 days, and in rod fabrication from about
9 days to 28 days. In each portion of the line there was an incremental
time after processing of about 7 days for post-campaign cleanout of equip-
ment. In Kllorod there was also some lag time between campaigns for data
analysis. Because of fixed contamination of equipment it was not possible
to thoroughly clean out after each campaign; a more extensive cleanout
and decontamination was necessary after the seventh.
Approximately 3 to 4 years had passed since the last purification of
the <334 used in the Kilorod program. Consequently, the daughters of 98
were nearly in equilibrium. The solvent extraction process removed the
220Th, 224Ra, and 2123 daughters by factors of about 2500, 5000, and 100,
respectively. Because of the relatively low efficiency for removal of
CLPb, presumably caused by extraction of its < Rn parent, the hard gamma
activity in the product decreased for approximately the first 2.5 days and
then began to increase, approaching the activity from initially pure
material efter 5 to 10 days.
The average radiation exposures in the Kilorod program were 19.5 and
19.2 millirems per man per week for sol-gel and rod fabrication, respectively.
Hand exposures were 62 and 113 millirems per man per week in sol-gel and rod
12
fabrication.
These operator doses are significantly higher than those
experienced by the supervisors, who may be thought of as "controls" for
the program. The dose incurred in process operations from material
actually being processed was no more than 20% of the total. The dose
during processing operations from material held up in the equipment was
36% of the total. The dose incurred during post-campaign cleanout
operations was 34% of the total. The dose from in-cubicle maintenance
operations averaged 10% of the total.
The radiation level from holdup of material in the Kilorod process
was estimated on the basis of the radiation dose rates to film parks
placed in strategic areas inside the Kilorod cubicles. In the sol-gel
..
-.
process, the radiation background from material holdup was relatively
constant in campaigns 4 through 7. These data can be explained by
.
-
-
:
s
a
assuming a steady-state mass of about 2 kg of oxide, and exponential removal
of "old" material with a rate constant of about 0.15 per campaign.
miest
--,
,
The background levels in the rod-fabrication equipment coniinued to
.
increase from campaign to campaign. The data are best explained by
assuming that about 1.5 kg of oxide of the nearly 100 processed in the
first campaign was irretrievably lodged in the equipment.
Separate records were maintained of the radiation dose rates during
post-campaign cleanout operations. The dose from these operations, accumu-
lated over 7 campaigns, represented about 34% of the total dose. Approxi-
mately 60% of the total dose in the seventh campaign was incurred in the
post-campaign cleanout, period, during which "complete" decontamination
was attempted.
34F
*
-
-*
>:
'",
-
13.
--
Doses were also accumulated for maintenance operations performed
:
-
-.
inside the cubicles. These doses were 20, 10, and 2% of the quarterly
exposures during the first, second, and third yearly quarters of operation,
respectively. These exposures do not reflect the actual weight of main-
tenance operations. The predominant effect of maintenance 18 in delaying
the process – requiring that materials be processed at longer post-
purification times. A similar effect occurs from other delays in the
process, caused by holding materials for analys18, holding off-specification
materials for blending, etc.
4.1 Radiation Data Evaluation
A model was then developed (Appendix) to explain the Kilorod data
and to provide a b4618 for extrapolating dose rates to other lines having
a nominal capacity of 10 kg/day. Operator doses are assumed to velry
directly with the production rate, cu content, effective activity of
the fuel, and shielding factors and inversely with the number of operators.
The model was believable since the same constant of proportionality
explained exposure data obtained from Savannah River mechanical line
operations during the preparation of 233,0g. Based on this model and
Incorporating process Improvements that are indicated from Kilorod results
we were able to predict dose rates for other 10 kg/day plants (Table 4).
A breakdown of the parameters that were assumed in our estimate of
the maximum practical upper limit of 20 ppm 2320 in 23 for fabrication
in an unshielded glove box line is shown in line 1 of the table. Our
experience in Xilorod with semiproduction-scale operations leads us to
conclude that it is not practical to operate at an average post-purification
time of less than 7.5 days in the sol-gel process. It is not feasible to
nye EFISI
3:1
-..

Oliin arc 66-3651
Table 4
PREDICTED DOSE RATES IN GLOVE BOX FACILITIES FOR
FABRICATING 233002-ThO2 FUELS AT IOkg/day
(8 OPERATORS-5 DAYS/WEEK)
POST PURIFICATION
DOSE
TIME (days)
TIME I
FROM
(days) | NUMBER FRESH WEEKLY
UICI |2331/23211 SOL GEL FABRICATION BETWEEN OF MATERIALI DOSE
CONCEPT FACTOR (%) ppm BEGINENDO BEGIN ENDO SOL. EXT. CAMPAIGNS (%) (mrem)
SHIELD233y|2324 SOL GEL FABRICATIONI-_'days
400
37
680
40
29C
600
BATCH ] 3 203 12 :7 16
5
CONTINUOUS 1 3 200 2153 4 4.8
10
SBR LINE
(SOL GEL)
0.
125 250 3 12 7 16 1 5
HTGR LINE
BOSPHERESİ 0:1 | 25 | 250 3 12 7 | 16 | 11 | 5 |
ASSUMES 20% OF PROCESSING TIME FOR CLEANOUT.
1. DOSE CONTRIBUTION FROM MAINTENANCE IS 10% IN SHIELDED LINE,
... UNSHIELDED LINE.
IS HOLDUP EQUIVALENT TO KILOROD.
S HOLOUP EOUVALENT TO KILOROD.
560
| 250
i
... ----
i.im
-
-.
-
.
15
-
-
use the solvent extraction product at post-purification times shorter
than 2 to 3 days because of (1) the post-purification time that accrues
during collection and evaporation of a batch, and (2) because the product
-
-
-
.
.
.
-
-
--
-
must be held up until good statistical accuracy 18 assured for uranium
--
---
content, nitrate-to-uranium ratio, and other variables that must be known
to achieve specification-grade product. Equipment maintenance, off-
specification products, and batch residues are often responsible for a
several-doy delay in the average post-purification tiine for the campaign.
Assumptions and estimated results for an extremely optimistic fabrica-
tion scheme are shown in line 2 of the table. The scheme assumes that
purified <330, one day old, is delivered to the sol-gel process at one-day
intervals. It is further assumed that the fraction of a daily batch held
up in the equipment 18 a factor of 4 less than that for Kllorod, the.t
material having age greater than 4 or 5 days will be dissolved and recycled
through the solvent extraction plant, and that "complete" equipment decon-
tamination can be made after each ten batches without serious economic
penalty from equipment throwaway and loss of fissile material. Waiving
operational problems, we conclude from the results in the table that a
<330 content of about 200 ppm in 2334 18 the upper limit for processing 3%
253002-Tho, fuels at 10 kg/day in an unshielded glove-box line for average
process exposures of 40 miliirems/week.
Estimates of the dose rates for shielded glove-box lines processing
typical Seed-Blanket Reactor fuel by the conventional sol-gel process, and
High Temperature Gas-Cooled Reactor fuel by the sol-gel microsphere process,
are shown in lines 3 and 4 of the table. We arbitrarily assumed that there
hi
16
18 a factor-of-4 le88 holdup in the equipment for a microsphere process
than in conventional sol-gel, primarily to show the magnitude of the
effect. We conclude that these fuels could not be processed even with
the shielding provided in the Kilorod Facility; shields to provide dose
attenuation by a factor of about 100 would be required. This 18 beyond
what can be accomplished with shadow shielding.
5.0 Application of Kilorod Data to Plant Scale-up
1.10 Kilorod data have allowed the evaluation of process results in
such a manner that it can be extrapolated to larger scale fabrication
plants. However, it should be noted that the Kllorod Facility did not
include the assembly of fuel elements, nor did it include the processing
of different enrichments which are normally required in fuel element
designs in order to optimize fuel element reactor core performance.
Therefore, the Kilorod experience has influenced our scale-up studies in
& more general sense; that 18, the data cannot be extrapolated directly
to every type of fuel which may be envisioned, but each fuel type must
be analyzed on its own to determine what type of processing plant is
requiied. Specifically, we are interested in the type of equipment to
be used and the shielding provided the operators.
Two studies have been made“,5 to ascertain the costs of the sol-gel,
rod fabrication, recycle scheme and to establish the shielding requirements
of plant capacities ranging from 60-3700 kg/day. In these studies, one
of the fuel element designs selected was the SSCR because of its similarity
to existing Kilorod technology. .
.-
.
.
..
Because greater than 70 per cent of the dose received by Kilorod
.
a
operators was the result of exposure to aged material holdup in equipment,
N
17
we are interested in the plant cleanout cycle. To determine the effect
of material höldup and the effect of cleaning the plant at various
intervals, the shielding was calculated for three conditions, assuming
that the operator woui.d be allowed no greater thea 1 mrem/hr. The three
conditions included; (1) no material holdup in the fabrication line;
(2) 3 kg of aged oxide would be held up in the equipment but woulä be
released after 5-day processing intervals, and (3) 3 kg of fuel would be
held in the equipment during processing but would be released after 30
days. It is obvious from Fig. 3) there is very little difference between
Hhst
the no material holdup case and the 5-day cleanup case. The 30-day
cleanup cycle for the 60 kg/day plant is shown on the upper curve.
In the foregoing example, it was assumed that the exposure limit
for personnel would be i mrem/hr or 40 mrem/week. This tolerance 18
in keeping with Kilorod experience and allows a safety factor for main-
tenance and emergency conditions. If it 18 desirable to increase the
exposure limit the shielding requirements may decrease. Figure 4 presents
9 family of curves obtained showing the shielding requirements for varying
U concentrations as a function of the allowable exposure.
It is possible to conclude from this study that cleanup every 5-10
days will be necessary to minimize radiation buildup to an acceptable
level.
of
An important question at this point is the cost of fabrication frel
under the various conditions which are imposed according to the assumption
regarding material age, quantity and <34 concentration. Figure 5 shows
the effect of <20 concentration on the cost of fabricating the SSCR
elements. In the calculations performed to obtain this data, it was
ORNL Dwg 66-1675
-------
-20 W
(u!) 7331S.
CONCRETE (in)
F-----------
.....
:
:
---- NO MATERIAL HOLDUP
--CLEAN UP EVERY 5 DAYS
-CLEAN UP EVERY 30 DAYS
yoo
..........
102
ilillo
10
ppm 232 U IN HEAVY METAL
103
Fig. 3
SHIELDING REQUIRED IN 60 kg/DAY PLANT FOR SSCR FUEL ELEMENTS
.
-
-

"
La
.
19
. -
ORNL Dwg 6'j-3656
PERMISSIBLE EXPOSURE (mr/hr)
- 0.5
- --2.5
1.0
-----5.0
430
ASSUMPTION: CLEAN UP EVERY 5 DAYS
-
----
------
STEEL (in)
Oriña pņ ņ ņ
CONCRETE (in)
19
i
102
1034

LUIT
ILITI
UULII|
10 .
ppm 232U IN HEAVY METAL
Fig. 4
VARIATION OF SHIELDING REQUIRED WITH PERMISSIBLE EXPOSURE
IN 60 kg/DAY PLANT FOR SSCR FUEL ELEMENTS

ORNL Dwg 66-3657
60 kg/DAY PLANT
FABRICATION COST ($/kg HEAVY METAL)
230 kg/DAY PLANT
930 kg/DAY PLANT
3700 kg/DAY PLANT
டடபட்ட
100
102
103
Fig. 5
ppm 232V IN HEAVY METAL
EFFECT OF 2320 CONCENTRATION ON THE COST
OF FABRICATING SSCR FUEL
-
-
-
-
-
assumed that the plants would be semi-remote or remote with the limit of
semi-remote fabrication varying from 5 to 10 pprn SEU in heavy metal. AB
can be seen from the curves, the effect of CB concentration on the cost
deminishes as the plant increases. Further analysis of the cost penalty
associated with ou in the fuel and assumptions regarding the type tab-
rication plant is provided hy Fig. 6. This figure depicte the cost
variation with plant capacity and for different modes of fabrication; that
18, remote with recycle thorium, remote recycled uranium but virgin thorium
{50 ppm 32 in heavy metal), semi-remote fabrication, glove box, and
finally a hooded plant for the fabrication of Su in virgin thorium.
,
.
...
Ar. important comparison 18 shown in Table 5 which reflects the capital
operating ratios and the ratios for the total fuel fabrication costs.
It should be noted that included in the capitul and operating ratios are
those operations which are still perforred in every fabrication plant,
but which are always contact operations such as the preparation of hard-
-*
-'*
4.
1.
ware components and other miscellaneous services required for the
fabrication of fuel. In addition, the hardware costs are substantial
and tend to minimize the cost penalty associated with remote fabrication
when compared with hooded plant fabrication.
Conclusions
The following conclusions may be made from the experience gained in
Kilorod:
(1) A large amount of data 13 nov available which indicates the
sol-gel vibratory fabrication recycle scheme 18 a workable system.
(2) Reasonable radiation exposure estimates can be made for the
requirements of the thorium fuel cycle.
ORNL Dwg 66-3658
-REMOTE (RECYCLE Th)
REMOTE (RECYCLE U, VIRGIN Th)
-SEMI-REMOTE (RECYCLE U, VIRGIN Th)
GLOVE BOX (RECYCLE U, VIRGIN Th)
-HOODED (235U, VIRGIN Th)
22
FABRICATION COST ($/kg HEAVY METAL)
- AMORTIZATION RATE: 22%
PLANT OPERATING DAYS
PER YEAR: 260
E SINGLE PURPOSE PLANT
LULUI
IIII!!
102
104

Fig. 6
PLANT CAPACITY (kg U + Th/OPERATING DAY)
EFFECT OF PRODUCTION RATE AND MODE OF FABRICATION
ON THE COST OF FABRICATING SSCR FUEL ELEMENTS
ORNL Dwg 66-3659
Table 5
COST RATIOS FOR COMPARISON OF REMOTE AND
HOODED PLANTS FABRICATING SSCR FUEL ELEMENTS
PLANT CAPACITY
(kg HEAVY METAL/DAY)
60 / 230 1 930 1 3700
RATIO OF REMOTE TO HOODED COST
23

CAPITAL
1.23
1.18
1.14
OPERATING
1.52
1.38
1.41
1.34
TOTAL (INCLUDING HARDWARE)
1.29
1.21
1.15
1.10
050 ppm 2320 IN HEAVY METAL; VIRGIN THORIUM
24
(3) That direct fabrication 18 feasible with: 019-97% Tho, fuels
which contain less than 20 ppm <GU in the 25.50. With shadow shielding,
this limit car. be increased to 200 ppm. With shadow shielding and repeated
cleaning and recycling, this limit is 600 ppm.
(4) Plants with larger capacities will require shielding when
operating under sustained conditions.
7.0 Acknowledgments
The efforts of the many persons in the Chemical Technology, Metal
and Ceramics, and Analytical Chemistry Divisions which brought about the
successful operation of Kilorod is gratefully acknowledged. The authors
would like to acknowledge the technical reviewers of the paper, D. E.
Ferguson and R. G. Wymer. Finally, we would like to note the valuable
.
.
contribution of E. V. Sheldon and W. L. Poe of Savannah River in providing
.
.
radiation data.
.
-.:
.
8.0 References
-
-
1.
A. L. Lotts, J. D. Sease, R. E. Brooksbank, A. R. Irvine, F. W.
Davis, "The Oak Ridge National Laboratory Kilorod Facility,"
Proceedings of The Thorium Fuel Cycle Symposium, Gatlinburg,
Tennessee, December 5-7, 1962.
....
..
2. D. E. Ferguson, 0. C. Dean, D. A. Douglas, "The Sol-Gel Process
for The Remota Preparation and Fabrication of Recycle Fuels,"
.....
Proceedings of The Third United Nations Conference on The
-
-
-
-
-
-
Peaceful Uses of Atomic Energy, Geneva, Switzerland, August 30
-
-
-
-
to September 10, 1964.
-
-
-
-
-
"
-
-
-
-
-
25
3. C. C. Haws, J. L. Matherne, F. W. Miles, J. E. Van Cleve, "Summary
of The Kilorod Project – A Semi-remote 10 kg/day Demonstration of
DUO, -Tho, Fuel Element Fabrication by 'The ORNL Sol-Gel Vibratory
Compaction Method," ORNL-3681, August, 1965.
A. L. Lotts, D. fo. Douglas, Jr., "Refabrication Technology for The
Thorium-Uranium-233 Fuel Cycle," IAEA Panel on Utilization of
Thorium in Power Reactors," Vienna, Austria, June 14-18, 1965.
5. J. M. Chandler, F. E. Harrington, "A Study of Sol-Gel Fuel Prepara-
tion Costs for SSCR and HTGK Reactors," ORNL-TM-1109, April 8, 1965.
..
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it is:
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:
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•
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E
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-...-
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S
A
E
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APPENDIX
A mode). was developed to explain the Kilorod data and to provide a
basis for extrapolation of exposure data to related glove box lines for
fabrication of fuels containing U. This section contains equations
20g
and symbols used in the model, activity buildup curves for the -TI
activity in G, and a table of experimental data that provides a basis
for the model.
Basically the model assumes that in related glove box lines the
total operator dose per unit of fuel processed 1^ invariếnt if the data
are normalized by accounting for the shielding factors, 2324 content of
the fuel, and the effective activity of the hard gamma -emitting daughters
of the EU decay chain during the processing period. We have based the
analysis on the -Uºti daughter because this daughter contributes a large
fraction of the gamma dose rate and rapidly attains equilibrium with
the other hard gamma emitting isotopes of the 29 decay chain. Total
body radiation exposures control for the range of parameters of interest
because allowable hand-arm exposures are higher by a factor of 15 and
typical ratios of hand-to-body dose rates are in the range of 2-to-5 for
typical fuel handling operations in unshielded or shadow-shielded glove
box lines.
The Kilorod data (Table A-l) were used to determine a constant of
proportionality, K, for the model. Such a constant has also been calcu-
lated for experimental data obtained at Savannah River and the Rabcock
and Wilcox Company at Lynchburg, Virginia. The constant, K, should
indeed be constant in glove box lines that require about the same
degree of operator attendance per unit of production. This criterion
does not necessarily apply to the Savannah River data because those data
were obtained for a line that only involved precipitation, filtration,
washing, calcination, and canning of 10 -0,0g powder. The agreement
between Savannah River and Kilorod data tends to make the model more
believable, however. The lower value of K that was ootained in the B and W
rod fabrication line can be rationalized on the basis that the density of
fuel per unit of length in the line is very small because very long rods were
.
processed in small batches. We have no satisfactory explanation for the
lover value of K in the B and W sol-gel and sizing operations.
An alternate test of the reproducibility of gross radiation exposure
data between glove box lines may be made by comparing the radiation dose
rates at the outside of the glove box from a normalized batch of fuel.
Such a comparison has been made for the experimental data in Table A-l
by calculating a constant 5, which has units of rems/man-week per
effective number of curies in a batch. This constant is larger for the
Savannah River operations because the Savannah River operators were, on
the average, relatively closer to a batch.'
-
.
-
*
-
EQUATIONS
Dkg = KFaF EXĀM
Fsa = 4/200 BEYA
Dow = 5000 Di P/O
Ā = 4g + At + App + KA
M = 1+ 2 (ka + ky/FB)
M
=
1
+
tk F)
m' 8
1.8
x
1
A4 = 1.8 *2009
XE
1
(0-1)
Ac = At + Afp + n(tp-t,] ico
5
&
tf+jAt
1(2-3) - (0-1-j)e-2]e-j2 | Adt
+38t
D-
Ag = A + A
+ = { [(0-) - (0-1-j)e4le J4 A (ta + jot)
SYMBOLS
Der = Total body dose incurred by operators per unit of fuel processed,
Bg rem/kg fuel
mw
D
K
= Average operator dose rate for 40-hr exposure, mrem/man-week
= An experimentally derived constant, 75 and 75 for sol-gel and rod
fabrication, respectively
E
= CSU content of fuel, weight fraction of "Su in fuel
X = ppm 232, in 233, mg 232y/kg 2337,
Fa = Self attenuation and shape factor for fuel batch
F = Shield attenuation factor, ratio of shielded to unshielded dose rate
cutside glove box
A = Average activity of <UOTI in uncontaminated fuel during the processing
f period, curies 208ri/mg 232U
A. - Activity of CU TI from the thorium in the fuel (formula assumes 50% of
natural thorium activity), curies 208T1/mg 2320
Arn =
Afp
Tl equivalent activity of the fission products in the fuel
(determined by shielding calculations or by difference), curies
save impas
4
nec
= Average activity from fuel holdup averaged over n campaigns, curies
208T17mg 232U
k
= Conversion fector for dose effectiveness of held-up material, 0.35 in
sol-gel and 0.20 for rod fabrication
Az = Average activity from fuel holdup during periods of postcampaign
cleanout
Ā
= Average activity of fuel, including background, during the processing
period
= Activity multiplier for dose contribution during periods of cleanout
and maintenance
ļ, = Conversion factor for dose effectiveness of held-up material during
periods of cleanout and maintenance, 0.20 in sol-gel, 0.19 in rod
fabrication
c
= Unshielded dose rate at a distance of 24 in. from the center of a
typical batch of fuel,
hr
B
P
0
= Mass of fuel per batch, kg fuel/batch
= Fuel production rate, kg fuel/8 hr
= Number of operators per 8 hr shift
k
= Conversion factor for dose effectiveness in unshielded maintenance
operations, 0.006 in Kilorod
to = Postpurification time at the beginning of processing of material from
& solveat extraction campaign
te = Postpurification time at the end of the campaign
to = Average postpurification time in the period of postcampaign cleanout
Linis
At = Time between solvent extraction campainis
n
= Number of campaigns before "complete" decontamination
2
- Removal rate constant for material held up in equipment, 0.15 per
campaign for sol-gel, zero for rod fabrication
N
= Weight fraction of thorium in the fuel
Table A-1. Radiation Exposure Data for 'WU-SU Processing Ulcralions in Glove
E
&
W
Kilorod
Sol Gel
Through Sizing, Rod
Calcination Fabrication
nan River Line
Savannah River "B" Line
Solids Handling
Camp. I Camp. II Camp. III
Sol-Gel
Through
Sizing
Rod
Fabrication
Fuel processed
1000
30
82
2330, kg
43
59
2.5
6.3
1000
30
6.3
10
0.026
-
-
0.8
0.4
0.91
244
3
82
2.5
3.9
11.7
0.027
1.1
0.4
0.91
244
3
0.026
53
1.5
0.4
0.985
4.2
3
<11.7
11.7
0.027
38
42
42
3.5
1.33
4
time of fuel
P, processing rate, kg fuel/shift
B, batch size, kg fuel/batch
E, 233u content, kg 233v/kg fuel
x, 2324 content, mg 232J/kg 2334
0, number of operators per shift
Average activity and effective postseparation
A. (fresh fuel only), curies 20871/mg 2324
to (fresh fuel only), iiys
* (with background, curies 20871/mg 232
M, multiplier for cleanout and maintenance
Fae, self attenuation and shape factor
F, effective shield attenuation factor
Dmw average operator dose rate, mrem/man-week
Die = D /5000 P, rem/kg fuel
Do = D/1000 B, (rem/man-week)/(kg fuel/batch)
c = F F EXĀM, curies/kg fuel
K = Dke/C, rem/curie processed
Ky = D, M/C, (rem/nan -week)/(curie/batch)
5.5 (6)
3.75
6.7 (6)
1.8
1.00
1.0
0.1
:
8
6.6 (-5)&
16.5
21 (-5)
1.8
0.58
0.1
19.5
1.2 (-3)
2.0 (-3)
2.2 (-5)
55
160
1
9.2 (-5) 5.5 (6)
20 3.75
28 (-5) 6.7 (5)
1.oº.
0.5 1
0.1
19.1
2.1 (-3) 0.15
1.9 (-3) 0.51
2.5 (-5) 1.5 (-3)
75
100
230 . . 340
37 (-5)
60
38 (-5)
1.0
<0.2
1
28
2.0 (-3)
2.4 (-3)
<0.8 (4)
1.1 (-4) 37 (-5)
~20 - 60
~3.3 (4) 38 (-5)
1.0 .
0.58
1
300 130
0.12 8.8 (-3)
0.75 0.011
1.36 (-3) 2.4 (4)
90
36
550 45
1 :
0.5
140
0.076
0.35
0.74 (-3)
100
470
200
>24
30
46.6 (-5) = 6.6 x 10-5
background duc to material holdup, Th, and tission products.
CDoses from cleanout and maintenance are not included.
" theoretical values of K for exposure at distances of i?, 2), and 30 in. t'ro! the source are 360, 200, Chadt 1:0.
! .
..

ORNL DWG 66-97
TTTTTTTTTTTTTTT
T
TTT
ION EXCHANGE
-10 YEAR AGING
-3.8 YEAR AGING
ZI YEAR AGING
20871 ACTIVITY (curies/mg2320)
ti"
KILOROD
SOLVENT EXTRACTION
3.8 YEAR AGING
- PURE 232
COMPLETELY SEPARATED
FROM DAUGHTERS
SCALE CHANGE
5
10
15
70
100
200
300
20 30 50
POST PURIFICATION TIME (days)
The 20871 Activity from 2320 Decoy as a function of Pose Purification Time, Method of Pur fication,
and Aging Time before Purification.
ORNL DWG 66-98

10-1
TTT
. day
sicuries 208,1)
Irzez Bu
Adi: Ad di-! Adt
10-5 LIL! Hilelut
10
100 400
POST PURIFICATION TIME forday)]
The Effect of Post Purification Time on the Integral of the 208TI Activity
Function.
i
TE
2.
-
56
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.W
e
-
*
-
..
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..
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-
A
..
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-
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-
-
.
1*
Re:
*
V
,
-.
, -
-
-
.
-
<
-.
:
1
1
.
1.
IN
1
II 1"
"
"
AM
.
1
:
-
!.
END
DATE FILMED
7 / 29 / 66







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