Since the deposit of Uranium ore is limited, nuclear energy (based on fission) is a nonrenewable energy source.
On December 20, 1951, EBR-I, located in Idaho, powered four 200-watt lightbulbs, indicating the first successful attempt of generating electricity by fission.
Formidable accidents at Chernobyl and Fukushima remain as a persuasive reason for environment activists to oppose construction of nuclear power plants.
Since Deuterium and Tritium are almost inexhaustible, nuclear energy (based on fusion) is a renewable energy source.
Unlike hydrogen bombs, Tokamak reactors utilize very strong magnetic field to retard the fusion process.
Since farther space travel requires a vast amount of energy, it seems that the controlled nuclear fusion is the only viable way for humans to become a interplanetary species.