Workers at the Sellafield nuclear reprocessing site in Cumbria plan to strike after their union accused management of "going cold" on attempts to reach a pay deal.
Maintenance staff and engineers intend to walk out for 24 hours from 06:00 GMT on Tuesday.
Unite regional officer Graham Williams said bosses appeared to have "adopted a new hard-line attitude" on the talks.
Sellafield said it was working to minimise disruption during the strike.
"However, strikes by their nature are designed to cause disruption and people should expect traffic problems while pickets are in place," a spokesman said.
Mr Williams said the imposed pay rise of 1.5% was "completely unacceptable" and threatened further action.
"We had talks with management which were very positive but, a week later, the atmosphere had dramatically changed - it was as if the shutters had come down," Mr Williams said.
"The strike is a shot across the bows and more strikes are on the cards in the run-up to Christmas if the management does not engage in constructive talks."
About 3,000 GMB members staged a 24-hour strike in September over the pay dispute.
Unite has 2,000 members at the plant, out of a workforce of 10,000.