The legal basis for Switzerland's nuclear energy policy dates back to 1946 when Parliament approved the first resolution of the Federal Council concerning the promotion of nuclear energy. Legislation governing the use of nuclear energy was incorporated into the Federal Constitution in 1957, and the Federal Council approved the Atomic Energy Act two years later, on 23 December 1959. In 1978, the resolution of the Federal Council concerning the Atomic Energy Act resulted in the introduction of a general licence and the requirement of evidence of demand for the construction of nuclear power plants, while at the same time, responsibility for the safe disposal of nuclear waste was transferred to producers. On 1 February 2005, the Atomic Energy Act and associated Federal Council resolution were replaced by the Nuclear Energy Act and the Nuclear Energy Ordinance. Following the reactor accident in Fukushima (Japan), Federal Councillor Doris Leuthard announced in mid-March 2011 that the pending procedures for handling applications for general licences for new nuclear power plants had been suspended. Then in the course of 2011, with their decision to withdraw from the use of nuclear energy on a step-by-step basis the Federal Council and Parliament laid the foundations for a new energy policy (2050 Energy Strategy). The intention is to decommission Switzerland's five nuclear power plants when they reach the end of their service life and not to replace them with new ones.In Switzerland, nuclear energy is used solely for peaceful purposes, e.g. for producing electricity and for application in medicine, industry and research. The 10-year average annual proportion of nuclear energy used for producing electricity is 39% (up to 45% in winter), which is above the European average of 33%. Switzerland's five nuclear power plants have a total capacity of 3.2 GW, and an annual availability rate of approximately 90%.