Chernobyl Nuclear Power Plant CIA Files - Paperless Archives

14 'fOP SECRET
ium. Ten percent of the plutonium-equivalent
produced in, or after, 1955 was assumed to
be tritium. This is about the maximum amount
that can be obtained from the graphite-moderated
type of reactors that account for most
of the Soviet production, when they are fueled
with natural uranium. The cumulative t,ritium
stockpile so derived was reduced each year by
the amount of tritium decay.
38. Gaseous diffusion plants are found at
four places in the USSR-Verkh-Neyvinsk in
the Urals, Tomsk in western Siberia, and Angarsk
and Zaozerniy in central Siberia. Some
of the older gaseous diffusion buildings probably
have been shut down either permanently
or for the purpose of effecting improvements.
39(
B. U-235 Production
36. Natural uranium contains only some
0.72 percent U-235, the isotope which is essential
for nuclear weapons utilizing uranium as
the source of an explosive chain reaction. The
USSR, like the US, uses the gaseous diffusion
process to enrich natural uranium, i.e., to increase
the U-235 content to some 90 percent
of the total uranium content, a ratio necessary
for weapon grade material( .
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