Workers at the Sellafield nuclear site are to stage a 24-hour strike in a dispute over pay.
Members of the GMB union will walk out at 6.01am on September 27 in protest at an imposed pay rise of 1.5%.
GMB official Chris Jukes said: "Despite repeated requests to try and get Sellafield management to come to the table to talk, it is clear that they seem intent on being intransigent and petulant as usual in their attitude to dispute resolution."
Mr Jukes added: "No-one likes to take strike action but GMB members have been given a pay cut, on top of a 0.25% increase last year, and their pay has failed to keep up with rising prices.
"Like everyone else, GMB members have bills to pay.
"Meanwhile, those at the top seem more interested in their big performance bonuses, as the gulf between them and those working on the shop floor at Sellafield gets ever wider.
"Clearly GMB members have signalled that they have had enough."
GMB members voted for industrial action by more than three to one in a ballot earlier this month.