French-owned EDF Energy has said it will not extend the operating lifetimes of two plants at the Hinkley Point B nuclear power station beyond a planned shutdown in summer, despite officials raising concerns over the danger of blackouts in the months that follow.

The company, the UK division of France’s EDF, sent a memo to staff in which it said it would not postpone the closure of the two reactors in Somerset, southwest England, which are scheduled to be shut down on 8 July and 1 August.

The closure of the plant will remove nearly 1 GW of power generation capacity from the UK’s system – enough to supply 1.5 million homes – before a winter in which the war in Ukraine is expected to weigh heavily on electricity supplies.