Editing Thorium Reactor Waste and Proliferation (section)

=== Uranium-233 ===
U-233, the fissile product of the thorium cycle, has been tested in nuclear weapons (the US ''Operation Teapot'' test of the ''MET'' device in 1955 used a partial U-233 core). However, in practice, U-233 bred in a thorium reactor is always accompanied by '''uranium-232''' (U-232), produced by parasitic reactions in small quantities.

U-232 has a 69-year half-life and decays through a chain that produces '''thallium-208''', a powerful gamma emitter (2.6 MeV). This gamma radiation:

* Makes the material extremely difficult to handle without heavy shielding
* Makes it impossible to process covertly — detection is straightforward with standard radiation monitoring equipment
* Would prematurely detonate a nuclear device through irradiation of conventional explosives during assembly

Alvin Radkowsky, designer of the world's first full-scale commercial nuclear power plant (Shippingport), estimated that a thorium reactor's plutonium production rate would be less than 2% of that of a standard reactor, and the plutonium's isotopic composition would render it unsuitable for detonation.