Current nuclear reactors work by fission nuclear reactions. These chain reactions is generated in case control systems fail, generating continous reactions causing a radioactive explosion that would be virtually impossible to contain.Probably the most alarming disadvantage is the use of the nuclear power in the military industry. The first use of nuclear power was the creation of two nuclear bombs dropped on Japan during World War II. This was the first and the last time that nuclear power was used in a military attack. Later, several countries signed the Nuclear Non-Proliferation Treaty, but the risk that nuclear weapons could be used in the future will always exist.Advantages of nuclear fusion versus nuclear fission