Navy’s oldest serving submarine returns to service following radioactive leak

HMS Tireless, one of the Royal Navy's Trafalgar class hunter-killer submarines, has returned to service following a leak of radioactive material into its reactor compartment earlier this year.

The submarine was forced to return to its home port, HM Naval Base Devonport, while on operational sea training off the coast of Scotland in February 2013 after elevated levels of radioactivity were detected in the reactor compartment.  The problem was traced to a leak of reactor coolant, and the reactor compartment was decontaminated and repairs made while the submarine was berthed at Devonport.

Philip Dunne,  Minister for Defence Equipment, Support and Technology, described the incident as “a very small coolant leak” which posed no risk to the public, the submarine's crew, or the environment, but later admitted that leakage had occurred over a period of approximately 192 hours and that radioactive emissions from the submarine had been vented to the atmosphere following its arrival at Devonport.

HMS Tireless is the oldest submarine currently in service with the Navy, having entered service in 1984.  The submarine is close to the end of its life and has been assessed by the Ministry of Defence as having a minimal asset value, but was nevertheless repaired and returned to service, leaving Devonport at the beginning of July to set sail on a three-month overseas deployment.

The Navy intends to retain ageing 'Trafalgar' class vessels such as HMS Tireless in service for longer than originally planned in order to be able to meet its operational requirements following delays in introducing 'Astute' class submarines in service.  The Defence Nuclear Safety Regulator (DNSR), responsible for overseeing nuclear safety within the Ministry of Defence, has recently expressed concerns that as a result, the Navy's first generation pressurised water reactors (PWR1), which are based on 1950s technology, will remain in service for longer than intended.  DNSR's annual report for 2012 warns that “the phasing out of PWR1 plant has been slower than intended due to the delayed entry into service of the Astute Class.  As a result, the Trafalgar Class are operating at the right hand end of their “bathtub” reliability curves and the effect has been seen in a number of emergent technical issues over the last few years”.

To read more, download Nuclear Information Service's briefing on the HMS Tireless coolant leak here:


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