Firefighters at the Sellafield nuclear reprocessing plant are to strike after “last-chance” talks broke down.
More than 60 members of the GMB union will stage a series of 24-hour walkouts in a row over pay grades.
The union said members did not want to strike but had been “backed into a corner”.
Sellafield Ltd has previously said it was committed to resolving the dispute, but it also said it had made plans to keep the site safe during any action.
Strike dates have not yet been announced.
Talks last week were adjourned to allow both sides to consider proposals and counter-proposals.
Speaking before the latest meeting got under way earlier, Chris Jukes, GMB senior organiser, said: “After years of being underpaid, it’s time they were given their due.”
Sellafield Ltd, which operates the site, said it was “carefully considering” its position.
A spokesman added: “In the meantime the Sellafield site continues to operate safely and securely, as normal.”