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Enriched uranium -Reply



Mike Lewandowski wrote:

"Can anyone provide a reference for determining the isotopic distributio=
n for
enriched uranium?  Specifically, given a sample of 93% enriched
uranium=
, how
can I determine the composition of the other 7%?  Is it appropriate to =
assume
negligible U-238 so that the remainder would be U-234?  Thanks for
your=
 help."


A good reference is the DOE's "Health Physics Manual of Good
Practices for Uranium Facilities" EGG-2530, 1988

I will add a few comments concerning the specific example provided (i.e.
a sample with 93% enriched uranium).  First of all, care must be taken
not to confuse the weight percent of enriched uranium with the percent
of uranium isotopes on an activity basis.  That is, 93% enriched uranium
(EU) means that on a weight basis, 93% of the uranium is U-235 - the
remainder, on a weight basis, is almost entirely U-238.  However, on
an alpha activity basis, practically all of the activity from 93% EU is from
U-234 - for high enriched uranium a typical U-234/U-235 activity ratio is
about 30.   Alpha spectroscopy is commonly performed to determine the
activities of the uranium isotopes, which are then used to calculate %
EU. 

Figure 2-2 in the above reference provides a nice illustration of total
radioactivity by isotope vs. % weight U-235.

Regards,

Eric Abelquist
abelquie@orau.gov