[ RadSafe ] Nuclear Fuel Cycle and Waste

[goldinem at songs.sce.com]

Casper,   you asked about the years to "cool off" when radiation hazard of
spent fuel is no worse than before irradiating.  The best source for that
data is (based on Bernie Cohen's work) in Raymond Murray's book:
"Understanding Radioactive Waste."  Page 129 of the latest (5th) edition
shows that irradiated fuel toxicity is equal to the initial uranium at
14,000 years for reprocessed fuel and 120,000 years for unprocessed spent
fuel.  The figure shown was adapted from B.L. Cohen, Am. J. Phys. 54(1),
Jan. '86 and refers to dose contributions from all radionuclides and
probability of ingestion by humans.

Noting that the graph and data refer to "toxicity" I vaguely recall seeing
some curves someplace that also showed the gross radioactivity of spent
fuel was roughly equivalent to the original ore at about 1000 years, but I
haven't found that reference (yet).

Regards,  Eric

Eric M. Goldin, CHP
<goldinem at songs.sce.com>