Nuclear risks rule Devonport out as an option if Trident quits Scotland

The UK’s Trident nuclear submarines could not be rebased at the Devonport naval dockyard in Plymouth for safety reasons if an independent Scotland orders the fleet to leave, according to a report from Scottish CND.

Information obtained by Scottish CND under the Freedom of Information Act indicates that Vanguard class submarines carrying Trident nuclear missiles do not have the necessary safety clearances to dock at Devonport.  Devonport has frequently been mentioned as an alternative base for Trident in the event of Scotland voting for independence in the 2014 referendum, but the report shows that the risks resulting from bringing submarines armed with Trident missiles into the city of Plymouth would be unacceptable to safety regulators.

Although Vanguard class submarines are refitted at Devonport, nuclear armed Trident missiles are unloaded from the submarine before it enters the dockyard.  The Ministry of Defence (MoD) has told Scottish CND that “nthe Devonport Naval Base nor the Devonport Dockyard, which is owned and operated by Babcock, safety case permit the berthing of an armed Vanguard class submarine”.  Furthermore, the Defence Nuclear Safety Regulator, responsible for overseeing the safety of the MoD’s nuclear programmes, “has not provided any advice on the feasibility of docking of an armed Vanguard class submarine in Devonport Dockyard”.

The Devonport naval base is in a densely populated area in the heart of the city of Plymouth and an accident involving nuclear weapons at the dockyard would put thousands of people at risk.  Around 166,000 people live within five kilometres of the Devonport dockyard, compared with just 5,200 within the same distance of the Faslane naval base in Scotland where Trident submarines currently dock.  Even though the population near Faslane is far smaller than that around Devonport, MoD has concluded that the risks from “societal contamination” that could result from a major nuclear accident were “close to the tolerability criterion level”.  

The MoD’s worst-case accident scenario for a Vanguard class submarine assumes that all the conventional explosives in the eight Trident missiles carried by a submarine detonate, causing all the plutonium in the 40 nuclear warheads on board the submarine to be dispersed to the surrounding area.  Calculations by Scottish CND suggest that if such an accident occurred at Devonport a wind blowing from the south-west would disperse radioactive material over much of the city of Plymouth, massively exceeding the MoD’s tolerability criteria for radiation doses to members of the public.  

Scotland is due to vote on independence in 2014, and the Scottish National Party has that stated it intends to order Trident out of the Faslane naval base on the Clyde in the event of a yes vote.

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