MoD will not refuel HMS Victorious

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HMS Vengeance in dry dock in Devonport. Image credit:Institute of Mechanical Engineers

On 5th November the government announced that it will not refuel HMS Victorious, the second oldest nuclear powered Vanguard-class submarine. The oldest one, HMS Vanguard, is currently in Devonport dockyard in Plymouth for deep maintenance and refuelling at a cost of £204m. HMS Victorious is due to go into Devonport after HMS Vanguard leaves in 2019.

During an earlier deep maintenance all four of the Vanguard-class submarines were fitted with a nuclear reactor core type, named Core H, which was designed to last for the whole of the remaining service life of the submarines. However, in 2012 radioactive material was discovered in the primary cooling circuit in the prototype Vanguard reactor at Dounreay, This was believed to be due to a fuel element breach and a decision was taken to refuel HMS Vanguard during its deep maintenance period as a precaution.

In the announcement Defence Secretary Gavin Williamson said that the decision not to refuel HMS Victorious as well was based on an “evidence based assessment”, but did not give any further details about the assessment. When the decision to refuel HMS Vanguard was announced it was said that it would not be safe to examine the Dounreay prototype reactor for three years after it was shut down. Permission to begin removing the fuel from HMS Vanguard was given by the Office for Nuclear Regulation in April 2017 and the phase of operations which includes removing the fuel from the Dounreay prototype reactor, is due to last until 2022.

Williamson said the MoD will work with the regulators to ensure the safe operation of the submarine fleet and that “[t]he safety of the United Kingdom’s submarine force remains our highest priority.”

The nuclear reactor design used in the Vanguard-class submarines is known as the PWR2. They are the second generation Pressurised Water Reactor design the UK has built to power nuclear submarines. The Astute-class submarines which are currently being built are also  powered by the same PWR2 reactor. The Defence Nuclear Safety Regulator (DNSR) is responsible giving approval to the MoD for operating submarine reactors. The MoD has censored all the annual safety reports of the DNSR dating back to April 2015, citing reasons of 'national security'.

The new Dreadnought-class submarines will be powered by a new reactor design, the PWR3, which is based on a US reactor design. Before the fuel element breach was discovered in the Dounreay prototype reactor a decision was taken not to build a prototype for the PWR3 reactors as had been done for the previous submarine reactor designs.