Plutonium
its another fuel for the nuclear reactor, plutoniium is smaller and it gives off more energy (and is blue... i think) but we only have 1 fuel for the nuclear reactor i was thinking we could have a new fuel source.
recipe is n/a
also periodic table shows actinium , thorium , protactinium , uranium (already implemented), neptunium , plutonium , americium , curium , berkelium , californium , einsteinium , fermium , mendelevium , nobelium , lawrencium