Workers at the Sellafield nuclear decommissioning facility have voted in favour of strike action over pay disputes.
Members of the GMB union voted by more than three-to-one to cease work at the site in Cumbria.
It claims the decision followed the company ignoring requests for further pay talks after it imposed a below-inflation pay rise of 1.5%.
In June this pay offer was rejected by 88% of union members based at the facility.
Two thirds of Sellafield workers will also have to pay up to an extra 6% on their pensions from next year.
Chris Jukes, GMB Senior Organiser, said: “GMB members at Sellafield have had enough with this unfair treatment that has seen their pay fail to keep pace with inflation over recent years.
“The decision to take industrial action is never, ever taken lightly but shows the level of real anger on the site.”
A spokesperson for Sellafield said: “We believe that a no-strings attached 1.5% pay increase is both fair and reasonable.
“We made that offer based on company affordability and it was accepted by the Prospect Union which has collective bargaining rights for the largest group of our workforce.”
The GMB strike date will be decided later this month and the Unite union is also due to ballot its 2,000 members at Sellafield.
Firefighters previously planned to go on strike at the site, which was later suspended.