Amber warning: Britain’s ageing nuclear submarines a risk – Navy's watchdog
Five Trafalgar class submarines, some of which are almost 30-years-old, are suffering reliability issues with their nuclear reactors, according to a report put online by the Ministry of Defense (MoD) that covers 2012-2013.
The UK’s Royal Navy nuclear safety watchdog, the Defense Nuclear Safety Regulator (DNSR), said that while at the moment problems are being dealt with, it issued an amber warning that “attention is required to ensure adequate safety performance.”
The hunter-killer submarines, which were launched between 1984 and 1991, are expected to operate for at least 33 years with the final sub in the class, HMS Triumph, not expected to be mothballed until 2022.
“As a result, the Trafalgar class are operating at the right hand end of their ‘bathtub’ reliability curves”, warns the DNSR. This means that the number of reliability problems experienced by the boats increases dramatically as they reach the ends of graphs shaped like bathtubs. All technical issues which have emerged in the last few years “can be directly attributed to the effects of aging,” the MoD states.
The Trafalgar class subs were already meant to have been in the knackers yard but have been forced into staying at sea longer because of prolonged delays with their replacement Astute class boats. After billion pound budget overruns on top of serious construction and teething problems, only two of the seven planned attack submarines are in service with the Navy.
There have been several accidents on board Trafalgar class submarines in recent years. HMS Tireless suffered a reactor coolant leak off the west coast of Scotland in February, which lasted 192 hours. In a separate incident, the same sub released radioactive air into the environment which the MoD insisted was “well within the normal permitted limits for discharges to the environment”.
In 2007, meanwhile, a small explosion which also occurred aboard Tireless resulted in the death of two sailors and the injury of another. The accident took place while the submarine was submerged under the Arctic icecap during a joint British-American exercise.
The DNSR report does not specify what the technical problems are but John Large, an independent nuclear safety expert, told the Guardian that the problems facing the Trafalgar submarines are the same as those faced by the UK’s first generation of Magnox nuclear power stations, all but one of which have now been taken out of service.
The main risks, explained Large, are the catastrophic failure of components in the pressurized reactor system, such as the circuit pipework and the reactor vessel itself. Steel, particularly irradiated steel, becomes more brittle as it gets older, making it more likely to crack.
“It seems as if admirals in Whitehall have overruled nuclear safety by demanding that the remaining elderly boats are held in service as a string and sticky-tape stopgap measure,” said Large.
The DNSR also warns that the Vanguard class submarines which carry the UK’s nuclear deterrent are also “likely to exhibit plant aging effects” as their running lives are extended to the early 2030’s. They entered service in the 1990’s.
The MoD also stressed, as it has done in previous reports, that a shortage of skilled nuclear staff, partly due to higher salaries in the civilian nuclear sector and insufficient efforts to recruit and retain personal, remained a problem for the safety of the UK’s nuclear submarine fleet.