Denaturation of
fissile materials suitable for
nuclear weapons is the process of transforming them into a form that is not suitable for weapons use and can not easily be reversely transformed. For
uranium 235 this is straightforward, by mixing it with
uranium 238, but for
plutonium it is more difficult and/or less effective, because other plutonium
isotopes are either also suitable for weapons or not available and impractical to produce, while mixing with a different element allows chemical separation.
The situation with
uranium-233 is more complicated, as U-233 is difficult to store safely, which is both an advantage and a disadvantage. Decay of the associated
uranium-232
Uranium-232 () is an isotope of uranium. It has a half-life of around
69 years and is a side product in the thorium cycle. It has been cited as an obstacle to nuclear proliferation using 233U as the fissile material, because the intense gamm ...
produces
thorium-228 with a radioactive half-life of 1.9 years and several short-lived daughter nuclides; these daughters include some very hard gamma-ray emitters like
thallium-208
Thallium (81Tl) has 41 isotopes with atomic masses that range from 176 to 216. 203Tl and 205Tl are the only stable isotopes and 204Tl is the most stable radioisotope with a half-life of 3.78 years. 207Tl, with a half-life of 4.77 minutes, has the ...
and
lead-212
Lead (82Pb) has four stable isotopes: 204Pb, 206Pb, 207Pb, 208Pb. Lead-204 is entirely a primordial nuclide and is not a radiogenic nuclide. The three isotopes lead-206, lead-207, and lead-208 represent the ends of three decay chains: the uraniu ...
. After approximately one year, the alpha activity of these decay products is several hundred curies per kilogram of U-233, and the penetrating gamma radiation is a thousand times greater than that from plutonium. Aged U-233 is thus radiologically self-protected from all but the most determined misuse.
Isotope separation
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