Re: Pu239/240 ratio

[Franz Schoenhofer <schoenho@via.at>]

At 11:35 18.08.2000 -0500, you wrote:
>
>I'm looking for some additional references for the Pu239/240 ratio from
>fallout.  I have a few reference but they seem to be in contention with
>each other.  I do also realize that the ratio changes by location so
>reference of the site would also be important.
>

The ratio depends on the plutonium used in the weapons, whether it was
"super grade" plutonium with little Pu-240, which means, that the uranium
fuel had been irradiated for a short time, or whether a larger percentage
of Pu-240 was present in the bomb plutonium because of longer irrdiation of
the U-238. Therefore it can be expected that on a local basis like on
proving grounds, the ratios may differ, but on a global scale, there should
be more or less a uniform mixture of the two isotopes by the mixing power
of winds and rain, which distributed the fallout over the continents rather
uniformly - at least the fallout of the explosions in the Northern
Hemisphere were distributed relatively uniformly over the Northern
Hemisphere. In the Southern Hemisphere the number of atmospheric nuclear
bomb tests was rather small and of comparatively low yield. 

Please be careful, it is not possible to distinguish the two isotopes by
alpha-spectrometry, you need mass spectrometry, preferably accelerator mass
spectrometry. When you check data, please keep in mind the possible errors
and uncertainties of the measurements.

Franz

 
Franz Schoenhofer
Habicherg. 31/7
A-1160 Vienna
Austria
Tel.: +43-1-495 53 08
Fax.: same number
mobile phone: +43-664-338 0 333
e-mail: schoenho@via.at


Please note my new telephone number at my office!

Office:
Ministerialrat Dr. Franz Schoenhofer
Federal Ministry of Agriculture, Forestry, Environment and Water Management
Radiation Protection Department (BMLFUW I/8 U)
Radetzkystr. 2
A-1031 Vienna
AUSTRIA

phone: -43-1-71100-4458
fax: -43-1-7122331

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