Nuclear reactor accidents in the United States reactors and research facilities. This led to the introduction of the Price-Anderson Act in 1957, which was "an implicit admission that nuclear power provided risks that producers were unwilling to assume without federal backing". Nuclear reactor accidents continued into the 1960s with a small test reactor exploding at the Stationary Low-Power Reactor Number One in Idaho Falls in January 1961 resulting in three deaths which were the first fatalities in the history of U.S. nuclear reactor operations. There was also a partial meltdown at the Enrico Fermi Nuclear Generating Station in Michigan in 1966. The large size of nuclear reactors
Nuclear reactor safety system must be developed such that it absorbs as little radiation as possible. For this reason, materials such as magnesium and zirconium are used for their low neutron capture cross sections. The reactor vessel is the first layer of shielding around the nuclear fuel and usually is designed to trap most of the radiation released during a nuclear reaction. The reactor vessel is also designed to withstand high pressures. The primary containment system usually consists of a large metal and concrete structure (often cylindrical or bulb shaped) that contains the reactor vessel. In most reactors it also contains the radioactively contaminated