@argv_minus_one @goatsarah the kind of hydrogen used for nuclear fission is tritium and deuterium, heavy isotopes, which are byproducts of nuclear fission power (at present). Fusion Power stations, when they are up and running in 30y time, will only need tiny amounts. They will likely be able to breed their own fuel because fusion produces a lot of neutrons (which aren’t radioactive in the way the byproducts of uranium fission are). The neutrons can be used to make heavy water, which when split gives heavy hydrogen. At least that was the plan 30y ago when I studied plasma physics.