Workers at the Sellafield site in West Cumbria have begun further industrial action.
Members of the Unite union who work for contractors at the nuclear contract, are striking over pay.
The union says workers should receive a Sellafield-specific allowance because they are highly skilled and work in a hazardous environment.
Further industrial action begun on Saturday and is due to continue until October 13.
Unite represents around 1,500 workers.
Unite general secretary Sharon Graham said: “Our members are highly skilled workers operating in an extremely challenging environment. That this is the most significant industrial action at Sellafield in recent history speaks volumes about the levels of feeling among the workforce.”
A continuous overtime ban will start on October 14.
Unite said it remained committed to resolving the dispute. The union is calling on employers to return to the negotiating table to discuss the site specific proposals that would recognise the unique hazards and skills set required at Sellafield.
It said it would welcome the introduction of the conciliation service Acas if the employers wish to introduce them and warned further strikes were likely if there were no ‘meaningful and productive talks’.
A Sellafield spokesman said: “The industrial action taking place at Sellafield is the result of a pay dispute between some Unite union members and their employers.
“As the people involved are not employed by Sellafield Ltd this is not a dispute that we can resolve.
“Our priority, as always, is to maintain the safety and security of the Sellafield site.
“We have provided guidance to our employees who may be impacted in travelling to the site during the action.
“We will also continue to support Cumbria police as they work to minimise the impact of the action on the local road network.”
