Methods, processes, and systems of nuclear reactor cores are provided. In one embodiment, the reactor core may comprise a nuclear fuel rod inserted into each of a plurality of moderator blocks in the reactor core; e.g., wherein the fuel comprises plutonium, carbon, hydrogen, zirconium and thorium. In some embodiments, the fuel may comprise hydrogen-containing glass microspheres, wherein the glass microspheres may be coated with a burnable poison, and other coating materials that may aid in keeping the hydrogen within the microsphere glass at relatively high temperature. The disclosed methods, processes and systems may aid in providing energy to remote areas.