Workers at the plant which provides steam and power to the Sellafield site are set to strike over pay.
Members of union Unite who work for PX Ltd at the Fellside Combined Heat and Power Plant, have voted in favour of 24 hours of industrial action later this month.
The union said the 38 workers it represents had turned down two pay offers, the latest being 3.5% to 5% depending on a set of criteria.
The strike is set to start at 7am on August 19 until 7am on August 20.
Workers are also currently undertaking an overtime ban.
Members at PX Ltd who will be on strike include operators, team leaders, planners and buyers, the union said.
The union said according to its latest financial report submitted in 2024, PX Ltd had a turnover of £77m, making a gross profit of £15m and compared with the previous year it had a turnover increase of 61%.
Unite general secretary Sharon Graham said: “PX Ltd can clearly afford to pay our members for the vital work they do but is choosing to put profits over people. This dispute is completely caused by the employer’s greed.
“Unite will always back our members every step of the way in any dispute and this is no exception. The workers at PX Ltd have our full support.”
A PX Ltd spokesman said: “As always, px bases pay negotiations with its people/employees on affordability, fairness and the long-term sustainability of site operations.
“Regrettably, after several rounds of negotiations with Unite officials – who represent 38 workers at the Fellside Combined Heat and Power Plant, which PX operates – we have not yet been able to reach agreement.
“We have suggested a further meeting involving the Advisory, Conciliation and Arbitration Service (ACAS) to help find a way past the sticking points but at this stage, the union has declined to take part in such talks.
“We will keep the line of communication open and hope that strike action can be avoided but if Unite members do withdraw their labour, as a responsible business and employer, px will ensure the safe operation of the site.”
