I've troubles understanding how "nuclear" reactor works in this mod. Every time I look at what fuel it accepts, it's one of cubes. I tried to feed cubes into reactors, but no changes observed even after 500C. How is it supposed to work?
It's a two stage process. You need to put the cube in to warm it up, and then immediately after that is used put in a nuclear fuel cell. If the reactor has no nuclear fuel for more than a second or so it will revert to needing the cube once again.