[DennisP]

Good points, but in all of that they are specifically targeting enrichment and reprocessing, while allowing nuclear power plants.

A fusion reactor is a power plant. It produces neutrons but so does fission; in fact, conventional fission plants get a third of their power from plutonium that they breed from U238, and plutonium accounts for most of the long-term radioactivity in the waste.

By comparison, a fusion plant would have no uranium present for any legitimate reason, and assuming it's D-T it would need those neutrons to breed tritium. Tritium has a use in thermonuclear weapons but not without highly enriched fissiles, and tritium is also a byproduct of fission plants.

[leonidasrup]

Precisely because fusion reactor could be used for plutonium breeding they will be subject to the same controls and political pressures as fission power plants.

Operation of all fission power plants, outside of countries with nuclear weapons, is subject to very strict controls by International Atomic Energy Agency, which reports to United Nations Security Council. Also because each civilian nuclear power reactor breeds enough plutonium to produce multiple nuclear weapons each year, spent nuclear fuel is subject to the same very strict controls. (I know the the isotopic composition of this plutonium is miserable for weapon production, but nuclear weapons using reactor-grade plutonium have been build and tested).

https://en.wikipedia.org/wiki/Reactor-grade_plutonium

I don't know any thermonuclear weapon using highly enriched uranium. Highly enriched uranium is used only in few designs of nuclear weapons: nuclear weapons which you build when you don't have access to weapon grade plutonium, or nuclear weapons which have to survive strong external shocks - nuclear bunker busters. Plutonium Pu-239 based nuclear weapons are physically smaller and lighter, easier to place into missile nose cone.

https://en.wikipedia.org/wiki/Nuclear_weapon_design

[DennisP]

For the most part I think we're in vehement agreement. I wrote above that nuclear plants are permitted with inspection under the NPT, and I would expect D-T fusion to be the same. Your links also say that reactors are allowed in practice.

When I said "highly enriched fissile" I meant that to include plutonium. Weapons generally use Pu239, while nuclear waste plutonium is 58% Pu239 mixed with other isotopes, plus of course a lot of U238 and various transuranics.

There is one area where fusion reactors are clearly being treated differently, and that's by regulators such as the NRC, which has already decided to treat fusion reactors like particle accelerators and medical devices, rather than with the much more difficult process they use for fission reactors.