Nuclear fission was discovered in the 1930s. During the 1950s considerable research took place, particularly in the United States, the UK, France, Canada and the former Soviet Union, into the design and construction of commercial nuclear power stations.
In the UK, construction began at Calder Hall in Cumbria in 1953 on the UK's first commercial nuclear power station. Calder Hall was connected to the national grid in 1956, thus becoming the first nuclear power station in the world to provide electricity commercially. The reactors at Calder Hall were a prototype of the Magnox gas cooled reactor. A second prototype Magnox station at Chapelcross in Dumfries and Galloway was switched to the national grid in 1959.
Following these prototype stations, nine full scale Magnox power stations were built in the UK. Construction of the first of these began in 1957. Two Magnox stations were built outside the UK, one in Italy and one in Japan.
The early development programme in France also concentrated on gas cooled reactor technology. Nine gas-graphite reactors, which are similar to Magnox reactors, were built in the 1950s and 1960s. The US research programme instead principally concentrated on developing water-cooled reactors, such as the pressurised water reactor and the boiling water reactor ("BWR"). In the 1970s France adopted water-cooled reactor technology for all future commercial nuclear generation, initially based on US design.
In 1964 the UK decided to develop advanced gas cooled reactor technology (AGR) to succeed the Magnox stations as the principal source of nuclear power in the UK. Five AGR stations were built in England and two in Scotland.
In 1978 the then Government decided that for future nuclear power station design it would be appropriate to pursue the Pressurised Water Reactor (PWR) option, the most widely used design outside the UK. Construction of the UK's first PWR, Sizewell B in Suffolk, started in 1987 after the largest ever UK public inquiry from January 1983 to March 1985. Construction was completed in 1994 and electricity generation began on 14 February 1995 following receipt of the appropriate consents from regulatory bodies. Since Sizewell B, no further nuclear reactors have been built or ordered in the UK.