Official figures released by the MoD reveal that one in 10 nuclear safety posts - both civilian and military - are vacant. The MoD's own safety watchdog has warned that the staffing crisis poses "a significant threat to the safe delivery of the defence nuclear programme".
The revelations have been described as utterly shocking by the SNP's Westminster defence spokesman, Angus Robertson MP. "To find out there are so many vacancies in critical nuclear positions is totally unacceptable," he told the Sunday Herald.
"This is extremely dangerous and unsustainable and lays bare the reality of the risks of the shambolic MoD cuts agenda. The MoD must immediately explain what it is doing to rectify this and when."
Robertson was told by the UK Defence Equipment and personnel Minister, Philip Dunne, that the MoD was short of 165 suitably qualified and experienced nuclear personnel on March 31, 2014.
Some 60 of those vacancies relate to nuclear submarine activities, and 26 vacancies are at the Faslane and Coulport nuclear bases in Argyll.
Across all its conventional and nuclear land, sea and air operations the MoD has disclosed that it had 97 vacancies for 1321 posts it categorised as "safety critical" on April 1, 2014. In its annual safety report for 2012-13, it said its target was to get these vacancies down below 50.
The report described the overall shortage of suitably qualified and experience staff as "the top departmental safety concern".
Although the MoD insists that none of vacancies defined as "safety critical" is in nuclear operations, it has repeatedly been warned by its own advisers that nuclear safety is at risk. The Defence Nuclear Safety Regulator, the MoD's internal watchdog, has described shortages of skilled nuclear staff as "the principal threat to safety in the defence nuclear programme in the medium term".
Its report for 2012-13 warned of future problems because qualified staff were "spread thinly in places".
The report pointed out that there was an ageing demographic issue because nuclear engineers were approaching retirement and not enough were being recruited and trained in their place. There was also increasing competition from the civil nuclear power industry, which is seeking to expand in England and Wales, it said.
Staff shortages were also highlighted in a heavily censored 2009 "risk register" released by the MoD under freedom of information law. John Large, an independent nuclear engineer who has advised governments, argued the latest MoD figures underestimated the seriousness of the staff shortages.
The redefinition of some jobs suggested that the MoD had moved the goalposts, he said.
"The nuclear safety implications arising from this could be onerous," he continued. He pointed out that nuclear engineers would face increasing challenges as submarines aged and developed unexpected problems.
The MoD insisted, however, that the vacancies had not impacted on its ability to safety deliver the Government's military nuclear programme. The Defence Nuclear Safety Regulator had agreed that current safety had not been compromised, it pointed out.
No nuclear submarines are sent to sea without the "required personnel" onboard, said an MoD spokeswoman.