Would it be possible to add support for the https://mods.factorio.com/mod/Nuclear%20Fuel mod? In its default settings the Kovarex tech is removed, which seems to break the ability to research Californium processing. Additionally, because the Nuclear Fuel mod is intended to replace requirements for large amounts of 235U with Plutonium, actually building any of the True Nukes weapons is very hard because you won't have much 235U at all. It would probably make sense to swap 235U for Pu in all of the True Nukes recipes (or make it configurable, as Nuclear Fuel does for Atomic Bombs) if Nuclear Fuel is installed (or maybe just if Plutonium exists as an item type).

Thanks for letting me know, I have a couple of these changes to do, so it might be a few days (or weeks), as I'm pretty busy in real life.
Anyway, generally, those mods are quite easy to add support for, its just adding another line in an if statement or 2, and yeah, I'll change the Uranium to Plutonium at the same time - there might already be an if statement for that.
I probably won't add configurability, as that would be a little more work, although if anyone really wants it, I'll add it - I don't imagine it would be used that much.

Adding general support is a nightmare though, as I won't know the internal name of plutonium, and I wouldn't know that the mods loaded in the right order, so it'll be on a mod by mod basis.

Should be sorted in the latest version now.

Yep that looks good, cheers. One more question: the recipe for tritium-breeder-fuel-cell is hard-coded to uranium-235 - could/should that be changed to boomMaterial as well?

I wasn't really sure what to do for that. The problem is that mods which change the materials, etc. tend to change the fuel cycle, so the breeder cell might be weird. Also, the material used for boomMaterial might be plutonium, and I don't know whether tritium should use that or uranium - really it should copy whatever the mod does for its fuel cells, which is mod specific... I figured that other mods could write their own override code, or I could write specific code... I think I did the same for californium (although californium doesn't make much sense recipe wise - really it should be berkelium in a reactor, then centrifuge the result, but berkelium isn't a thing...).