In a serious environmental incident, official files have revealed that radioactive water from the UK’s most secretive nuclear weapons base was allowed to leak into the sea. The leak happened because old water pipes at the site were not properly maintained, according to a government pollution watchdog.
Where the Leak Happened
The leak took place at the Royal Navy’s Coulport armaments depot, located on Loch Long near Glasgow in western Scotland. This base is one of the UK’s most secure military facilities, storing nuclear warheads for the Navy’s four Trident submarines. These submarines are part of the country’s nuclear deterrent program.
How It Happened
- The base has around 1,500 water pipes, many of which were found to be past their design life.
- The Scottish Environment Protection Agency (Sepa) reported that repeated pipe bursts caused flooding inside sensitive areas.
- In one case, water became contaminated with low levels of tritium — a radioactive material used in nuclear warheads — and flowed into the sea through an open drain.
Sepa said these problems were caused by “shortfalls in maintenance” and poor asset management.
Past Incidents
The leaked documents show that:
- 2010 – A pipe burst at the base.
- 2019 – Two major bursts occurred, including one in August that flooded a nuclear processing area.
- 2021 – Two more bursts happened, one in another area containing radioactive substances.
In total, these incidents highlight a pattern of poor maintenance at one of the most sensitive military sites in the UK.
Secrecy and Delayed Disclosure
These details were kept hidden for years. The UK Ministry of Defence (MoD) argued that revealing them could harm national security.
- Journalists fought a six-year battle to gain access to the reports.
- In June 2025, Scottish Information Commissioner David Hamilton ordered their release, saying they threatened “reputations” rather than security.
- The files were finally made public in August after additional delays.
Expert Concerns
Defence experts have called the repeated leaks “shocking” and the secrecy “outrageous.”
David Cullen, a nuclear weapons specialist, said:
“This negligent approach is far too common in the nuclear weapons programme, and is a direct result of poor oversight.”
He also pointed out that the MoD is already spending nearly £2 billion on upgrading facilities at Coulport and nearby Faslane, yet serious maintenance failures still occurred.
Impact on the Environment
According to Sepa:
- The levels of radioactivity released were low and did not pose a danger to human health.
- However, these incidents created unnecessary radioactive waste and exposed weaknesses in the MoD’s maintenance systems.
- Loch Long, a sea loch connected to Scotland’s coastal waters, is now part of ongoing environmental monitoring.
The MoD claims that there have been no unsafe releases of radioactive material and that they follow the highest safety standards.
Improvements Made
Since these incidents:
- The MoD has introduced 23 new actions to improve safety.
- Sepa says there have been “substantial improvements” in asset management.
Annual reports on radioactive discharges from Coulport and Faslane are now published, showing no regulatory concerns.
