Hundreds of workers at the controversialSellafield nuclear fuel-reprocessing plant are set to walk off the job today over a pay dispute.
Three hundred staff plan to strike for eight hours from 2.00 p.m., disrupting production at the plant.
Trade unions GMB and Amicus said workers were protesting over pay differentials.
Sellafield's owner, British Nuclear Fuels Limited (BNFL), said safety at the plant, which manages nuclear waste and reprocesses spent fuel rods for customers in Britain, Japan and Continental Europe, would not be affected.
The action at the site comes a day after BNFL Chairman Mr Hugh Collum announced his resignation.
A BNFL spokesman said the timing of the announcement had "absolutely nothing" to do with the strike threat, but the unions said they hoped it would help end the dispute.
"We hope that this signals the removal of some barriers and that the company will now be willing to sit down and negotiate with us," said Mr Brian Strutton of the GMB.