In an oral statement to the House of Commons, the Defence Secretary, Philip Hammond, has announced his decision to refuel the nuclear reactor in HMS Vanguard during its planned deep maintenance period which begins in 2015.
The decision comes after low levels of radioactivity were detected in a prototype core that has been running at the Naval Reactor Test Establishment at Dounreay in Scotland since 2002.
The purpose of the prototype is to help assess how the reactor cores within submarines will perform over time. It has therefore been run for significantly longer periods and at a significantly higher intensity than those cores of the same type in submarines to allow MOD to identify early any age- or use-related issues that may arise later in the lives of the operational reactor cores.
Radiation exposure for workers and discharges from the site have remained well inside the strictly prescribed limits set by the regulators. Workers therefore remain safe and the local community is not at risk.
Indeed, against the International Atomic Energy Agency’s measurement scale for nuclear-related events this issue has been classed as ‘Level 0’, described as ‘below scale – no safety significance’. The Naval Reactor Test Establishment is, and remains, a very safe and low-risk site.
The refuelling of HMS Vanguard will enable her to operate successfully and safely in the future.
During his statement, Philip Hammond said:
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.
The refuelling will increase our confidence that Vanguard will be able to operate effectively and safely until the planned fleet of Successor submarines begins to be delivered from 2028.
The refuelling will be conducted within the currently planned dry dock maintenance period for Vanguard, which starts in late 2015 and will last for around 3-and-a-half years, and is therefore expected to have no impact on deterrent operations. The additional cost of refuelling Vanguard is estimated to be around £120 million over the next 6 years.
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.