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
Light-water reactor employ a cooling system that is physically separate from the water that will be boiled to produce pressurized steam for the turbines, like the pressurized-water reactor. But in some reactors the water for the steam turbines is boiled directly by the reactor core, for example the boiling-water reactor. Many other reactors are also light-water cooled, notably the RBMK and some military plutonium-production reactors. These are not regarded as LWRs, as they are moderated by graphite, and as a result their nuclear characteristics are very different. Although the coolant flow rate in commercial PWRs is constant, it is not in nuclear