AWE workers in Aldermaston and Burghfield will be staging a second 24-hour strike in a row over pensions.
The dispute centres around the threat to close the defined benefit pension scheme and substitute it with what unions are describing as an inferior alternative.
The strike, which will start at 00.01am on December 6, follows the breakdown in talks this week after Unite - the UK's largest unuion - had its counter proposals rejected by AWE management.
The first one-day strike took place on Monday November 14.
AWE workers will also be holding a lobby of the Houses of Parliament on December 6 and making appointments to see their local MP to raise their case.
The dispute has been given an extra edge by accusations that the Ministry of Defence (MoD) broke pension promises made a quarter of a century ago when the workforce was transferred to the private sector.
Unite regional officer Bob Middleton said: “We know that the continuous overtime ban, work-to-rule and withdrawal of goodwill from 15 November have severely hit the work at AWE and it faces fines from the MoD because of this impact.
"Under the AWE’s new plans, our members are set to lose thousands of pounds when they retire which is just plain wrong.
“Our members’ solidarity is strong and further industrial action is on the cards in the run-up to Christmas and the New Year, unless the management starts to negotiate in a constructive fashion.”
Unite members have voted by 92 per cent for strike action and by 97 per cent for industrial action short of a strike.
Currently, AWE scheme members pay 10 per cent of their salary into the scheme and the employer pays 26 per cent.
Under the AWE’s new proposals, employees will be able to pay from three per cent to nine per cent; with AWE paying from seven per cent (if an employee pays three per cent) to 13 per cent (if an employee pays nine per cent or more).
AWE plc, which employs about 4,000 people, is a consortium of two American-owned companies Lockheed Martin and Jacobs Engineering, and UK-listed Serco.
The union said that company bosses saw defined benefit pensions as ‘a soft target’ to save money for the benefit of shareholders.