Re: Yucca Mountain

[mgoldman@ucdavis.edu (Dr. Marvin Goldman)]

>Bob Flood wrote:
>>
>> >QUESTION: Is a time span of 10,000 years realistic?  Why should it be
>> >designed to last for such a long and unforeseeable time period?
>>
>> I've heard it said, but I have never tried to verify by my own calculations,
>> that a standard mix of spent fuel (mixed fission products) will decay to
>> about the same total activity per unit volume as the original uranium ore in
>> about 300 years. Has anyone done this calculation? If this is true, wouldn't
>> it be reasonable to require protection only until the radioactivity levels
>> are no worse than when they started?
>>
>> Bob Flood
>> Unless otherwise noted, all opinions are mine alone.
>> (415) 926-3793
>> bflood@slac.stanford.edu
>
>We have recently performed performance assessments to support closure of
>high level waste tanks at a DOE facility.  The
>isotopes that contributed most of the potential dose through the
>groungwater pathway during the 10,000 year period of
>interest were Tc-99 and Se-76.  The NRC has also focused on I-129.  All of
>these isotopes have very long halflives and remain
>long after the 10,000 years considered.
>
>What I am interested in, due to their very low specific activity, is it
>physically possible to consume sufficient quantities
>of these materials to receive a significant dose?  Some years ago, I
>performed back-of-the-envelope calculations for I-129
>and came to the conclusion that it was not possible.  Does anyone have
>references regarding this conclusion?
some years ago Book, S.A. performed some research on I-129 and concluded
that the specific activity question was such that iodine chemical poisoning
would occir long before any radiation dose of significance; in the late
'60's at UC Davis.  I think it is Health Physics or is an AEC report.