The UK Ministry of Defence (MoD) is facing calls to release details of a nuclear safety incident at HM Naval Base Clyde, a key facility for the country’s nuclear submarine fleet, earlier this year.
According to a report by Sky News, official figures indicate that a Category A event, the MoD’s highest severity classification, occurred at the Faslane base between January 1 and April 22, 2025. The MoD defines Category A as the most serious type of nuclear site incident but said this case was assessed as having “low safety significance” and posed no risk to the public or the environment.
Located on Gare Loch in western Scotland, HMNB Clyde serves as the Royal Navy’s headquarters in Scotland and hosts the UK’s Vanguard class submarines which carry Trident nuclear missiles.
In response to a parliamentary question from Scottish National Party MP Dave Doogan, Defence Procurement and Industry Minister Maria Eagle confirmed multiple incidents at Faslane and the nearby Royal Naval Armaments Depot Coulport, the storage and loading site for the Trident programme, between April 2024 and April 2025. These included one Category A, five Category B, 29 Category C and 71 Category D incidents at Faslane, and 13 Category C and 34 Category D incidents at Coulport.
Eagle said details of Category A and B incidents could not be released due to security concerns but stressed that “none of the events caused harm to the health of any member of staff or to any member of the public and none have resulted in any radiological impact to the environment.”
Defence Secretary John Healey also confirmed that all reported events were categorised as having low safety significance and were rated at level one, the lowest rating on the seven point International Nuclear and Radiological Event Scale. He said such incidents could involve equipment malfunctions, human error, procedural shortcomings or near misses without harmful consequences.
The call for transparency follows renewed scrutiny of the UK’s nuclear weapons programme after a joint investigation by The Guardian and The Ferret revealed that radioactive water leaked from Coulport into Loch Long in 2019 due to corroded pipes. The Scottish Environment Protection Agency said the discharges were “of no regulatory concern” while the MoD stated there had been “no unsafe releases of radioactive material” into the environment.
Scottish National Party deputy leader and Member of the Scottish Parliament Keith Brown said the incident raised serious safety questions: “With repeated reports of serious incidents at Faslane and now confirmed radioactive contamination in Loch Long, it is clear these weapons are not only poorly maintained but are a direct threat to our environment, our communities and our safety. Worse still, the Labour government is refusing to provide any details about the Category A incident.”
An MoD spokesperson said details could not be disclosed for national security reasons but maintained that the incidents posed no danger: “We place the utmost importance on handling radioactive substances safely and securely. Nuclear Site Event Reports demonstrate our robust safety culture and commitment to learn from experience. The incidents posed no risk to the public and did not result in any radiological impact to the environment. It is factually incorrect to suggest otherwise. Our government backs our nuclear deterrent as the ultimate guarantor of our national security.”