1952: Radioactive discharges to the Irish Sea begin.
1956: The Queen opens Calder Hall nuclear power station.
1957: One of two 'Windscale Piles', military plutonium production reactors, catches fire.
1964: Reprocessing of fuel from civil Magnox reactors begins.
1971: British Nuclear Fuels Ltd is hived off from the UK Atomic Energy Authority.
1973: Explosion in the 'Head End Plant' contaminates building B204.
1975: BNFL approaches Tony Benn, then Secretary of State for Energy, about building the Thermal Oxide Reprocessing Plant to replace the B204.
1976: Major radioactive leak at Windscale. Cumbria County Council approves Thorp.
1977: Windscale planning inquiry under Mr Justice Parker.
1978: Mr Justice Parker reports and approves the plant. Commons gives approval. 1979: Three Mile Island accident.
1981: Name is changed from Windscale to Sellafield.
1983: Work begins on facilities for spent fuel.
1985: Construction work begins on Thorp.
1986: Chernobyl accident.
1992 February: Thorp completed at a cost of pounds 1.85bn - pounds 1.9bn has been paid in advance by overseas customers. BNFL build pollution treatment plant costing more than pounds 1bn.
1992 November: Public consultations on Thorp.
1993 August: Second two-month period of public consultation opens.
1993, 15 December: Government gives plant go-ahead. Greenpeace and Friends of the Earth mount legal challenges.