[ RadSafe ] Plutonium from Power Reactors

Brennan, Mike (DOH) Mike.Brennan at DOH.WA.GOV
Thu Apr 10 19:17:26 CDT 2008

Hi, Jarro.

I haven't looked at the numbers for a while, but as I recall Pu241 isn't
particularly desirable in fuel, as it doesn't have very good
characteristics, and it has an annoying half-life; neither short enough
to ignore nor long enough to not worry about.  While Am241 is a source
of gamma in the long run, it is minor compared to the activity of all
the fission fragments in fresh SNF (NOTE: Your mileage may vary,
depending on what model reactor, type of fuel, and operating

When you reprocess the fuel to separate out the U and Pu to make into
new fuel, presumably you would separate out the Am, also.  This would
mean that your newly fabricated fuel would only have as much Am241 in it
as in-growth from Pu241 that went into the fuel would cause.  (I admit
to not being an expert on SNF reprocessing, as SOMEBODY screwed that
whole industry up in the US).  In any even, the activity of the
reprocessed fuel would only be an issue for as long as it took for it to
be put into a reactor, and while it might be hotter than completely new
fuel, any group of people who have recently removed spent fuel from that
reactor can deal with it.  

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On
Behalf Of Jaro
Sent: Thursday, April 10, 2008 4:33 PM
To: radsafe at radlab.nl
Subject: RE: [ RadSafe ] Plutonium from Power Reactors

Brennan, Mike (DOH) wrote:

" the U and PU in the spent fuel isn't decaying enough to make a
difference, but the fission fragments are, so when eventually we do
reprocess the first couple years will be with easier to work with


Not necessarily:
Up to about 12% of the Pu in SNF is Pu241, which beta-decays to Am241
with a half-life of 14.4y.
Am241 adds a lot of gamma activity to the fuel -- even after all the
fission products have been processed out.

I don't know if European or Japanese MOX users get their fuel from
relatively fresh or old SNF stocks, but its clear that MOX from old SNF
would be pretty tough to handle, requiring considerable shielding during
fuel loading operations.
Some reactor types are only set up to provide shielding for SNF during
unloading, not for fresh fuel loading.


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