The prospect of building new nuclear power stations and replacing the Trident nuclear submarines are threatened by a shortage of inspectors, union leaders warned.
Prospect, which represents 15,000 scientists, engineers and inspectors in the nuclear industry, said there were not enough staff to meet current inspection requirements.
The union claimed there was a "crisis" in the recruitment of inspectors, partly because of pay.
Suitable qualified safety inspectors could earn 10% more in other industries, the union claimed.
Prospect official Mike Macdonald called on the Government to act on a recent review of salaries in the nuclear industry.
"Our members recognise the constraints on public sector pay but the commitment to review salaries of nuclear safety inspectors was agreed as part of the 2005 pay settlement."
