POTENTIAL FOR PRODUCTION OF WEAPON-GRADE URANIUM AT THE PLANNED BRAZILIAN URANIUM ENRICHMENT PLANT

• Document Type: FOIA
• Collection: FOIA Collection
• Document Number (FOIA) /ESDN (CREST): 06859456
• Release Decision: RIPPUB
• Original Classification: U
• Document Page Count: 6
• Document Creation Date: March 9, 2023
• Document Release Date: September 18, 2020
• Case Number: F-2017-01987
• Publication Date: July 29, 1977

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Supplement
to
Scientific Intelligence Digest
Saerei�
S1 SID 77-007 Supp. 1
29 July 1977
Copy N2 282
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'MERU-
CONTENTS
Page
Potential for Production af Weapon-Grade Uranium at the Planned Brazilian
Uranium Enrichment Plant
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The Scientific Intelligence Digest is produced solely by the Office of
Scientific Intelligence and the Office of Weapons Intelligence. The Digest
is coordinated within CIA.
rn
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SI SID 77-007 Stipp. I
29 Jul 77
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POTENTIAL FOR FOR PRODUCTION OF WEAPON-GRADE
URANIUM AT THE PLANNED BRAZILIAN
URANIUM ENRICHMENT PLANT
PREFACE
Under a 1975 agreement which provides for the construction of up to eight nuclear
pmet plant% and Au Within, West Gummy is poem* %mud construction ot
a small uranium enrichment plant in Brazil. Estimates have been made of the time
that would be required for production of highly enriched uranium at this plant.
SUMMARY AND CONCLUSIONS
The uranium enrichment plant which West
Germany plans to build for Brazil could be used to
produce weapon-grade uranium rather than the
reactor-grade uranium for which it is designed. Such
use will be within the technical capabilities of Brazil.
It would constitute a violation of safeguard
agreements, however, and would entail recycling of
enriched uranium through the plant in batches, which
could be detected fairly easily by inspection teams.
The tninimum time required to make highly
enri.ched uranium would depend on the approach
chosen and the amount and assay of enriched uranium
that is desired If Brazil were to start with natural
uranium, more than a year would be needed to
produce even a very small amount of weapon-grade
uranium (90-percent U-235). To produce 25 kilograms
of 90-pera-n1 12-235, which would be enough uranium
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for one nuclear device, about 1.5 years would be
required. To produce 100 kilograms, which is a more
practical quantity in light of the cost and effort
involved, about 3 years would be required.
If Brazil could start with reactor-grade uranium, the
time requirements could be reduced sharply. The
plant could produce 25 kilograms of 90-percent-
enrichPd U-235 in about 4 months, or 100 kilograms in
6 months.
An inefficient nuclear explosive could be made in
less time by producing uranium enriched to less than
90-percent U-235. Using 65-percent-enriched uranium
as an example, the minimum time required to produce
25 kilograms, starting with either natural or reactor-
grade uranium, would be 20 weeks or 4 weeks,
respectively. To produce 100 kilograms would require
38 weeks or 6 weeks, reipectively.
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MENET
DISCUSSION
The uranium enrichment plant to be built by West
Germany and Brazil will be a small plant intended to
demonstrate the feasibility of using the West German
(Becker nozzle) uranium enrichment process in a
commercial plant. It is designed to provide only low
enrichment of uranium; the plant will not contain the
nuir,ber of enrichment stages needed to produce
weapon-grade uranium (about 90 percent uranium-
235) in one pass. Brazil could produce highly enriched
uranium, however, by recycling uranium through the
plant several times in batches. This is a time-
consuming process.
The number of cycles that would be needed to reach
an enrichment level suitable for use in a nuclear device
and the time and material needed to produce the
desired quantity of highly enriched uranium depend
on the technical characteristics of the Brazilian
enrichment plant. Brazil could reduce the number of
cycles required, and hence the time needed to make
highly enriched uranium, by making major physical
alterations in the plant. These alterations certainly
would be difficult, would take many months, and
would be detectable. The more likely route to
production of highly enriched uranium is thus
believed to be straightforward recycling of enriched
uranium through the plant.
Several important technical characteristics of the
Brazilian plant have been calculated in the past
600 stages and their associated piping before any
enriched product material could be produced.
some of
these plant characteristics probably are in error. In
the plant will contain fewer stages than
indicate. Although this reduces the
estimated plant inventory of uranium to about 0.25
mt, it also means that an additional cycle is necessary
to reach an assay of 90-percent U-235.
A ble scheme for urani
suggest that the plant will have a capacity between
180 and 250 metric tons of separative work per year,'
a depleted material assay of perhaps 0.35 percent
U-235, and a cut' of 1/4. The Becker nozde separation
process that is to be used in the plant probably would
exhibit an enrichment factor' of 0.0148 at this cut.
From these technical data one would determine that
the plant probably is made up of about 600 stages and
that the plant normally would consume an estimated
458 metric tons (mt) of natural uranium per year while
producing about 58 mt per year of uranium enriched
to 3.2 percent U-233. A rough estimate of the
inventory of such a plant (the quantity of uranium
required initially to fill plant equipment) shows that
about 0.5 mt of uranium would be needed just to fill
�forparstive capacity figures can be used to determine uranium
production rams fora variety ot product enrichment levels. The cut
iletertairies the reLitise sires ail the enriched and depleted streams
1664,1114 kg)01 each stage in the plant. The clutch/tient factor
slamrasines the drg,ree to ishieb the assays of these two dreams
diger.
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Is presented in the figure. In the figure, -x- represents
a number equal to the number of metric tons of
weapon-grade uranium to be produced in the final
cycle. One can calculate, from the figure, the
minimum time required to produce any amount of 90-
percent U-235. To produce 25 kilograms (kg) for
example, which is enough to make one explosive
device, about 13 months would be required to
complete the initial (or normal) cycle.
It might be awkward for Brazil to run the plant for
such an extended period without demonstrating a use
for the accumulating product, although one could
argue that a stockpile of reactor-grade uranium is a
desirable buffer against unexpected shortages.
Alternatively, the first cycle could be cut back or
eliminated through purchases of outside enrichment
services. In that regard, each of the four to eight West
German power reactors to be built in Brazil will
require annually 35 mt of 3.2-percent-enriched
uranium which, for the most part, will have to be
Imported. A large amount of reactor-grade uranium,
therefore, should be available to Brazil under
safeguards.
Once the first cycle had been completed, the
remaining four cycles would take much less time. Only
about 4 months would be required to make 25 kg of
weapon-grade uranium from the reactor-grade
uranium.
For a number of reasons, it is unlikely that recycling
would be done for production of only 25 kg of highly
enriched uranium. An amount such as 100 kg, which
would permit construction of a test device and several
additional devices, would be more likely. Production
of 100 kg would require about 3 years, including 2.5
years for the first cycle and 6 months for the remaining
four cycles.
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A Scheme for Enriching Uranium in Cycles (x isa number that depends on the amount of
woapon-grade uranium to be produced).
If Bt.-ail were waling to settle for uranium enriched
to less than 90-percent U-235, which would yield a less
efficient nuclear device, the time involved could be
reduced sharply. Starting with natural uranium, the
minimum time required for production of 25 kg of
uranium enriched to 65-percent U-235. for example,
would be about 20 weeks. Production of 100 kg would
take about 38 weeks. Starting with reactor-grade
uranium. production of 25 kg or 100 kg would require
4 weeks or 6 weeks, respectively. The resultant
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uranium would be less appropriate than 90-percent
U-235 for use in a weapon, however, and thus might
not be considered worth the costs involved.
The technical difficulty of recycling uranium in
batches through the plant would not be prohibitive for
Brazil. Careful planning would be necessary, however,
to determine the optimum conditions for each cycle
and to prevent the possibility of creating a critical
mass of uranium in the plant as enrichment levels
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increase. Some Some fairly minor alterations to the material
feed and withdrawal systems also would be desirable.
but the risk of early detection might preclude such
modifications. Although within the technical
capabilities of Brazil, recycle operations could well
require more time than the minimum amounts
estimated above. In particular, the time required to
purge the process equipment after each cycle and to
account for all the uranium involved would depend on
the exactitude desired.
Although Brazil and West Germany have agreed
that the enrichment plant will be under International
Atomic Energy Agency ;:legua.-ds, no means of
implementing safeguards inspections has been openly
discussed. For consideration of possible safeguard
measures the data in the figure provide a good
indicator of the time and material necessary for a
recycling program, but these quantities are somewhat
a matter of choice; they depend on the precise manner
in which the plant is operated. Also, the exact
technical specifications for the plant, which would
permit a refinement of this estimate, are not yet
available to us. Nonetheless, some statements can be
inside concerning the safeguard mechanisms which
could be employed to assure detection of uranium
recycling at the Brazilian plant.
Because the cycles of a recycle scheme are separate
operations, there is no need to perform them together
as a set. The second cycle for example, using 3 percent
U-233 as feed material, could be followed by a period
of normal operations. The remaining cycles could be
performed at a later time. In fact, any one cycle could
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be performed in a series of short operations interrupted
by periods of normal operations. It is apparent,
therefore. that a safeguard inspection system for this
plant must provide a fairly continuous record of plant
operations if it is to assure detection of recycling. An
ideal safeguard arrangement would include constant
supervision of plant operations by the IAEA
Inspectors.
A technical means of assuring detection would be
possible by measuring and recording the assay of
uranium in each stage of the cascade. Several hundred
tamper-proof instruments would be required, which
probably would entail an unacceptable expense. On
the other hand, the number of instruments required
could be reduced with a small loss of safeguard
effectiveness, because enrichment stages in the plant
probably will be installed in groups and operated in
groups. The consequence of this grouping, which
reduces costly interstage valve connections, is that no
stage can be operated as independent from the rest of
the group. If there are 12 stages per group in the
demonstration plant, recordings from only 40-50
points in the cascade would suffice to determine the
performance of the entire cascade.
A simplification of this detection system could be
achieved by connecting each group of stages to one
central instrument with 40-50 tamper-proof tubes.
The central instrument would monitor the operation
of each group of stages and provide a composite record
to be examined periodically by inspectors.
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