All commercial nuclear reactors use nuclear fission. These are used in nuclear reactors and nuclear weapons. Reactions with neutrons are important in nuclear reactors and nuclear weapons. All current small modular reactors use nuclear fission. Helium is also used as filling gas in nuclear fuel rods for nuclear reactors. All commercial power reactors are based on nuclear fission. There are two primary isotopes used for fission reactions inside of nuclear reactors. Several experimental nuclear fusion reactors and facilities exist. Neutron radiation is essential to the working of nuclear reactors and nuclear weapons. The nuclear reactors shut down safely. Californium is produced in nuclear reactors and particle accelerators. Large releases of radioactivity from nuclear reactors are extremely rare. Taiwan has six nuclear reactors and two under construction. This is the principle for nuclear reactors and atomic bombs. Kr is released during the reprocessing of fuel rods from nuclear reactors.