HMS Vanguard leaves Devonport after 7 years of maintenance

HMS Vanguard, the oldest of the UK’s nuclear-armed submarines finally returned to the Clyde in May after an extended seven and a half years in deep maintenance. The original budget for the work was just over £200m but final costs have now been estimated at more than £500m. The work at Devonport naval dockyard took four years longer than planned, and included an unscheduled refuelling of its nuclear reactor after a radiation leak was discovered in the cooling circuit of the shore-based reactor at Dounreay, known as HMS Vulcan.

The PWR2 reactor design is also installed in the other three Vanguard class nuclear-armed submarines as well as the Astute series of conventionally-armed submarines. In 2018 it was decided that the other Vanguard submarines would not be refuelled. This decision appears to have been taken before a full examination had been undertaken on the fuel removed from HMS Vulcan.

Vanguard is to be fully tested during sea trials later, which are expected to culminate in a test launch of an unarmed Trident missile, as part of a Demonstration and Shakedown Operation towards the end of the year. The boat is then expected to rejoin the Vanguard fleet in early 2024.

The submarine appears to have been kept in Devonport for nearly a year while the maintenance work was being checked, before clearance was given for it to put to sea. A ‘rededication’ ceremony was held in July 2022 to welcome the vessel back to the fleet while it was still in dry dock at Devonport, and a press report later claimed it was ‘peppered with defects’.

In February 2022 it emerged that one of the issues discovered was that workers had accidentally sheared off at least seven bolts keeping insulation cladding on reactor cooling pipes and then glued the heads back on in an attempt to hide the mistake. NIS understands that the insulation was not critical to reactor safety but a failure to secure it may have created a hazard for crew members.

The Vanguard submarine fleet is expected to remain in service until they are replaced by the Dreadnought class, currently under construction. By 2030 HMS Vanguard will have been in service for 37 years far beyond its originally planned service life of 25 years. The MOD does not publish its expected end date for the Dreadnought programme, but the risk of delays to the programme appears be mounting.

The length of HMS Vanguard’s maintenance period has impacted the rest of the fleet, and recent reports of five-month patrols suggest that the remaining three submarine have not all been able to undertake patrols. The resultant pressure on vessels and crew is likely to be partly alleviated when Vanguard returns to service in 2024.

HMS Victorious arrived in Devonport on 26th June to begin its deep maintenance period.

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