Reactor-grade (as opposed to weapons-grade) plutonium has been hotly (no pun intended) argued over as to its suitability for nuclear warheads. From the open-source claims I’ve been reading, there are arguments that I’m not qualified to address the technical side of, but a couple of common themes have emerged:
- Every extant nuclear power has chosen to go ahead with the additional expense of weapons-grade plutonium rather than trying to make something out of reactor-grade material. There have been tests and rumors, but that’s it.
- Reactor-grade plutonium is hotter, more dangerous when exposed [making design and handling more difficult], requires more material for less explosive power, and is far more likely to fizzle (detonate instantly with a much lower yield).
- However, even the low yield (less than a kiloton) is still a radioactive Beirut explosion, raising fears of nuclear terrorism with stolen reactor-grade materials.
- Improved design can remove many of the shortcomings of reactor-grade plutonium.
- The increased yield uncertainty makes it less attractive for tactical operations.
Still, the technically “easiest” way just to make a nuclear explosion with national-level resources would be to use civilian reactor-grade plutonium to put together an atomic charge. The list of countries that could do such a thing is much longer than the conventional nuclear states. Granted, they’d be facing a large backlash to make an explosive charge that’s 1940s-level at best and has little practical military utility, but it’s what’s the most possible in spherical cow terms.