Workers at the Sellafield site in West Cumbria have voted in favour of taking further industrial action.
The workers, who are employed by sub-contracting firms at the nuclear complex, took part in a second ballot by union Unite this year.
Union members are demanding site-specific allowances, which they claim are paid at other nuclear sites across the country.
They first began industrial action in September last year. It concluded at the end of January. Workers did not strike from December 22 to January 2.
The union confirmed last month that its 1,720 members – who work for 31 firms – were reballoted.
The ballot started on February 25 and concluded yesterday, Thursday March 19.
The results of the most recent ballot show that there were 1,140 votes cast – around 66 per cent of those entitled to vote – and no ballot papers were spoiled.
681 voted in favour of continuing industrial action and 459 voted against.
Unite said it was now considering its next steps and would make a statement when any dates for industrial action were set.
When industrial action began at the site, striking workers took part in marches that were dubbed the Sellafield shuffle.
The marches were taking up to six hours to complete.
Later industrial action was covered by conditions from Cumbria police under the Public Order Act.
Marches were not allowed to start before 7am and had to conclude by 10am.
Any marches from Calder Bridge to North Gate had to start after the turn-off to Sella Park Hotel so that its business access could be maintained.
A Sellafield Ltd spokesman said: ““Unite has notified us its members have voted for industrial action in the ongoing pay dispute with construction companies working on our site.
“As the people involved are not employed by Sellafield Ltd this is not a dispute that we can resolve.
“Our priority, as always, will be to maintain the safety and security of the site and keep disruption to a minimum where possible.”
Unite has previously said the companies involved in the dispute were Altrad Services; Amentum Clean Energy; Amentum Enterprise Asset Solutions; AVRS Systems; Balfour Beatty; Careys; DSD; Design Grid; Enigma; Erith; ES Steel Ltd; Flannery; Impwood; Kaefer; Keltbray; Kier; LEL Nuclear; Mammoet; Meldrum; Mitie FM Ltd; Mitie Ltd; Morgan Sindall; NG Bailey; NRL; Nuvia; PC Richardson; PPS Electrical; Rhodar; Shepley; Sir Robert McAlpine; VGC Group; William King; G&M Lawson Ltd; Athena; Stobbarts Ltd and FB Taylor (Cable Contractors) Ltd.
