3 ms·

> Reactor-grade plutonium is still rigorously controlled, because it might be possible to make it explode, but nobody has ever done it. The US tested a bomb ma

• DennisP 7y ago
  From my source above: > a 1962 US test using UK plutonium from its Magnox reactors had a relatively a high level of Pu-240 but evidently less than ‘reactor grade’ as subsequently defined
  • jabl 7y ago
    Fair enough. Though to be pedantic, at the time of the test, it was considered reactor grade. The subsequent split of the definition of reactor grade into fuel grade (8-20% Pu240) and reactor grade (>20% Pu-240) occurred in the 1970'ies. That being said, there seems to be "evidence" (maybe more like conclusions that can be drawn from published articles by people with weapons experience etc.) that Pu with almost any isotopic composition can be used to make a usable (as in, very low probability of pre-detonation, low enough radioactivity to not pose a threat to personnel handling it) weapon. Now, I don't think that terrorist capturing a nuclear powered cargo ship and then making a Pu bomb is a particularly big worry. Making a Pu bomb from spent fuel (whether with weapons grade Pu or reactor grade) requires reprocessing technology (e.g. PUREX) as well as the engineering to create an implosion device, and is probably out of reach for non-state actors. The worry AFAICS with reactor grade Pu is that an advanced non-weapon state sitting on a big pile of separated reactor grade Pu (cough Japan cough) could relatively quickly (e.g. weeks/months) create a bomb if they so wanted, compared with building weapons grade Pu producing reactors and running them, which would be a several years long project.