Editing Thorium — Proliferation Resistance: The Weapons Question (section)

=== Why U-233 Is Difficult to Weaponize ===
The fissile material produced by the thorium fuel cycle is uranium-233. U-233 has excellent nuclear properties for reactor fuel but poses significant challenges for weapons use:

'''The U-232 contamination problem''':
In any practical thorium reactor or thorium irradiation environment, U-233 is inevitably accompanied by a small fraction of '''U-232***. U-232 is produced by various side reactions when thorium-232 and U-233 are irradiated.

Why this matters:
* U-232 itself is not a weapons concern — but its decay chain produces several isotopes that emit intense '''hard gamma radiation***
* Specifically, thallium-208 (Tl-208) in the U-232 decay chain emits a 2.6 MeV gamma ray — one of the most penetrating common gamma emitters
* This intense gamma radiation from the U-232 decay products makes working with U-233 in a weapons context extraordinarily dangerous without heavy shielding
* It also makes the material easily detectable at great distances — making illicit transport difficult
* The required shielding and remote handling technology is extremely expensive and beyond the capability of most non-state actors

This gamma radiation creates a substantial technical barrier to using reactor-produced U-233 in a crude nuclear device.