The Office for Nuclear Regulation (ONR) has given consent for Reactors 3 and 4 at Hunterston in Scotland to return to service for a limited period following scrutiny of operator EDF’s safety case. The advance gas-cooled reactors, which were built in 1976, underwent a shutdown in 2018 for detailed inspections following the discovery of cracks in the graphite bricks used in the reactor cores. At the time, EDF said that the 2mm cracks were within acceptable limits and are “a known phenomenon” for the type of reactor technology given its age and do not pose a safety risk. Under the ONR agreement, Reactor 3 can operate for a total of 16.7terawatt days and Reactor 4 for 16.52terrawatt days, which equates to around six months for each reactor, after which they will both enter the decommissioning phase. When EDF took ownership of the nuclear reactors, power generation from Reactors 3 and 4 (known as Hunterston B) was expected to end in 2016 but the firm said in 2012 that the date had been extended to 2023, although the end date has now been confirmed as 7 January 2022.
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