Nuclear power is the controlled use of nuclear reactions to release energy for work including propulsion for ships and submarines, and for the generation of electricity. Nuclear energy is produced by a controlled nuclear chain reaction and creates heat which is used to boil water, produce steam, and drive a turbines.
Nuclear (fission) power stations, provided 11% of the world's electricity in 2012, somewhat less than that generated by hydro-electric stations at 16%. Nuclear energy policy differs between countries, and some countries have no active nuclear power stations, or have phased them out. The first nuclear generated electricity, used to power four 200-watt light bulbs, was produced at the EBR-I reactor near Arco, Idaho, in 1951. This was followed in 1954 by the first grid-connected plant (in the USSR), and in 1956 by the first commercial plant (in the United Kingdom).
During the last decades of the 20th century, concerns about nuclear waste, nuclear accidents, radiation and nuclear proliferation led to an anti-nuclear movement. The 1979 Three Mile Island accident, the 1986 Chernobyl disaster, and the 2011 Fukushima disaster also played a part in stopping new plants in many countries, while the economics of nuclear generation and of nuclear decommissioning have also been factors. Despite this, some countries including China and India have continued to remain active in developing nuclear power, Germany will close its 19 nuclear plants by 2020, and is investing heavily in renewable energy commercialization instead.