A relief for the submarine service – HMS Victorious does not need nuclear refuelling

In March 2014 the MoD admitted there was a minor concern about the integrity of the nuclear reactors which power Vanguard class submarines. As a precaution, HMS Vanguard currently in refit at Devonport has been given a second new reactor core. This week the government quietly announced that technical assessments have now concluded this procedure will not be necessary for the other three boats.  

Between 2002 and 2012 all four of the Vanguard class Trident missile submarines underwent a Long Overhaul Period (Refuel) at Devonport and were retrofitted with ‘Core H’ pressurised water reactors (PWR-2). Core H was designed to last until the boats decommission and avoid the expense of another refuelling.

In January 2012, low levels of radioactivity were detected in the cooling water surrounding the Core H test-bed at the Naval Reactor Test Establishment (NRTE) at Dounreay. It is believed this has been caused by microscopic leaks in the cladding that surrounds fuel elements. This is not a major safety issue and the test-bed is deliberately run much harder than an actual submarine reactor. No problems had been found in operational reactors but it was deemed sufficiently serious that the decision to refuel HMS Vanguard was taken as a precaution. Controversially, government delayed making this announcement to Parliament until March 2014.

Unable to take risks with the availability of deterrent submarines, refuelling HMS Vanguard was an expensive insurance policy at around £270 million. The core replacement has added around £120 million to the refit cost. A further £150 million had to be spent on reactor infrastructure at Devonport and the Rolls Royce facility in Derby so as to retain the ability to manufacture Core H potentially, for HMS Victorious and the other two boats. These additional expenses were met from contingency funds held in the submarine programme, not the MoD’s annual budget.

Until now, it was unknown if the problem detected at Dounreay was a systemic design flaw with Core H or just a one-off problem with the test reactor. After extensive testing and examination of HMS Vanguard’s fuel elements for corrosion or distortion, it is now clear that Core H is sound and HMS Victorious, the next boat due for refit will not have to be refuelled (neither will HMS Vigilant or Vengeance at their subsequent refits).

Had a serious issue with Core H been identified, it could also have had implications for the Astute class submarines, which use the same design. The ‘all clear’ is a big relief for the Navy, already struggling with submarine availability. The Submarine Delivery Agency (SDA), now responsible for managing refits, will also be pleased to save at least £360 million. Avoiding refuelling will also cut the time each submarine must spend in refit and are unavailable for deterrent patrols, reducing the pressure on the other boats. The news will see a reduction in work for Babcock at Devonport but they still have a guaranteed flow of nuclear submarine refits and are working to prepare the site to receive the Astute class boats for deep maintenance.

There still remains much financial risk within the nuclear submarine enterprise as a whole but the shadow of reactor problems has now been lifted.

HMS Vanguard undergoing 4-year refit and nuclear refuelling in number 9 Dock at Devonport. She is due to rejoin the fleet in early 2020. (Photo: Maps data ©2017 Google)