Uranium-232
Uranium-232 is an isotope of uranium. It has a half-life of around
68.9 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 gamma radiation emitted by 208Tl makes the 233U contaminated with it more difficult to handle.
Production of 233U invariably produces small amounts of 232U as an impurity, because of parasitic reactions on uranium-233 itself, or on protactinium-233, or on thorium-232:
Another channel involves neutron capture reaction on small amounts of thorium-230, which is a tiny fraction of natural thorium present due to the decay of uranium-238:
The decay chain of 232U quickly yields strong gamma radiation emitters:
This makes manual handling in a glove box with only light shielding too hazardous, and instead requiring remote manipulation for fuel fabrication.
Unusually for an isotope with even mass number, 232U has a significant neutron absorption cross section for fission as well as for neutron capture.
