The Wylfa 1 is the first of the two units, each with 490MW capacity, of the Wylfa Nuclear Power Station located west of Cemaes Bay on the island of Anglesey, North Wales.
Both the units of the facility entered service in 1971 and were initially planned to be shut in 2010.
Although the second unit of the power plant was retired in 2012, the first unit’s operational life has been extended for further five years to 2015.
Fuel rods, which will be reprocessed in Sellafield, are already being removed from the second reactor.
Operated by Magnox and owned by the UK Nuclear Decommissioning Authority, the nuclear power plant generated around 1GW of atomic energy at peak to meet the 40% of Wales’ total electricity needs.
Nuclear Decommissioning Authority chief executive John Clarke said: "I am proud of the team’s innovative work which made this extended operational life possible, but the time has come to finally switch her off and move into the decommissioning phase."
Defuelling of Wylfa 1 unit is planned to commence during early summer 2016 and complete by late 2018. Full-scale decommissioning is expected to last several decades.
UK Economy Minister Edwina Hart said: "Wylfa has safely produced over 232 TWh of low carbon electricity since it started generating in 1971 – which has averted the production of over 200 million tons of greenhouse gases, making a significant contribution to Wales’ low carbon economy."
Horizon Nuclear Power, a subsidiary of Japan’s Hitachi, is planning to build two new reactors at an adjacent site.
Image: Wylfa nuclear power plant. Photo: courtesy of Magnox.
