Workers at the Atomic Weapons Establishment (AWE) in Aldermaston and Burghfield in Berkshire struck on Monday against the planned closure of their pension scheme.
The 24-hour strike involved members of the Unite and Prospect unions.
Prospect national secretary David Luxton said there was “solid support”.
Workers walked out in their hundreds for mass picket lines and then a protest march. The walkout was followed by action short of a strike from Tuesday.
Privatised AWE Plc—a consortium of Lockheed Martin, Jacobs Engineering and Serco—designs, manufactures and maintains Britain’s nuclear weapons of mass destruction.
It should be focusing on scrapping them instead.
But a victory for these workers could help turn the tide of pension scheme closures.
IT services workers plan shutdown
The result of a strike ballot of around 1,900 Unite members employed by Gatwick Airport Ltd was expected on Wednesday.
It follows a 96 percent vote to strike over pensions by BMW Group workers in an indicative ballot of around 4,000 Unite members ending last Tuesday.
The turnout was around 75 percent. Unite says a full strike ballot will follow.
Both firms are closing pension schemes despite huge profits and shareholder dividends.