The nuclear reactor of the UK’s oldest nuclear submarine, HMS Vanguard, will be refuelled during its planned deep maintenance period which begins in 2015 and will last for around 3-and-a-half years, UK Defence Secretary Philip Hammond, announced last week.
The decision comes after a radiation leak was detected in a prototype core that has been running at the Naval Reactor Test Establishment at Dounreay in Scotland since 2002, according to Hammond.
As explained by the Secretary, the low levels of radioactivity were discovered in the cooling waters of a test reactor in Scotland in January 2012, caused by a microscopic breach in the metal cladding which covers the reactor fuel.
Radiation exposure for workers and discharges from the site have remained inside the strictly prescribed limits, according to the statement, stressing that neither the workers nor the surrounding environment had been endangered in any way, as the event was classed as ‘Level 0’, described as ‘below scale – no safety significance’.
The timing of the announcement raised many eyebrows, as to why did it take over two years for the Government to disclose that the accident occurred.
The additional cost of refuelling Vanguard is estimated to be around £120 million over the next 6 years.
“The safety of the UK’s naval nuclear reactor at the test establishment at Dounreay and on our submarines is of critical importance to us, as is the maintenance of continuous at-sea deterrence. That is why I have taken the decision to apply the precautionary principle, even though there is no evidence at this stage that the problem detected with the test reactor is likely to present in the operational reactors.
“These low levels of radioactivity are a normal product of a nuclear reaction that takes place within the fuel, but they would not normally enter the cooling water. This water is contained within the sealed reactor circuit, and there has been no detectable radiation leak from that sealed circuit,” Philip Hammond said in a statement.
Naval Today Staff, March 11, 2014; Image: Royal Navy