Reactor 3 at Hunterston B remains offline, after being shut down since a routine inspection into cracks in its graphite core, in March.
Cracking of the graphite bricks in Advanced Gas-cooled Reactors such as Hunterston B is expected as the reactors age. However, the number of cracks found during the inspection of Reactor 3 has led to the licensee, EDF Nuclear Generation Limited, carrying out further inspections of the core.
Reactor 4 at Hunterston B was taken offline in October for an inspection of its graphite core.
EDF Energy has submitted a safety case for Reactor 4 and is preparing one for Reactor 3. The safety cases will be assessed by us to determine whether the reactors are safe to return to service. Neither reactor may restart without our consent, which will be given only if it is safe to do so.