Hundreds of union members, working as specialists, engineers and scientists at the former fast reactor, rejected a 1% pay offer from Dounreay Site Restoration Limited’s parent company, Cavendish Dounreay Partnership.

Talks led by Prospect union’s national secretary for Scotland, Richard Hardy, failed to reach agreement resulting in all three unions on the site – Prospect, GMB and Unite – accelerating their preparations for a strike ballot.

Hardy described the talks as candid and constructive. But the employer’s representatives were unable to agree to a union proposal that would have halted the ballot process.

“Negotiations have stalled over DSRL’s refusal to improve the 1% offer, despite massive increases in shareholder dividend payments, company profitability and senior directors’ pay.

“We understand that the DSRL representatives, including managing director Phil Craig, have to talk to their shareholders, but our members’ patience is running out.

“This is a government contract being delivered by the private sector, and we will not sit by while our members’ pay packets are used to prop up the directors’ pay and shareholders’ dividends. Our members are delivering the work and should be rewarded fairly.

“It is disappointing that we couldn’t strike a deal, and we are eager to listen to what the company says when we meet again on 24 January. But in the meantime, the strike ballot preparations will continue,” Hardy said.

Workers at the adjacent nuclear plant operated by Rolls Royce were recently offered 2%.

Dounreay opened in the 1950s and was taken offline in 1993. It is now at the centre of a multi-billion pound decommissioning programme.