ONR agrees to key safety limit change at Dungeness B
06 June 2014
A key safety limit at Dungeness B nuclear power station in Kent, southern England, is being raised to extend the life of the reactor, the BBC reported. The UK Office for Nuclear Regulation (ONR) has agreed to increase the amount of weight that graphite bricks at the core of the plant’s two reactors will be allowed to lose.
Dungeness B - Photo: EDF Energy
The graphite bricks act to moderate the nuclear reaction and become damaged through years of intense bombardment by radiation and the effects of the CO2 coolant. The bricks cannot be replaced, which means they are being carefully monitored as the reactors age.
The current weight loss limit for the graphite bricks at Dungeness is set at 6.2% but the ONR said EDF Energy, which owns and operates Dungeness B and the UK’s other ageing Advanced Gas-cooled Reactors (AGRs), applied to raise it to 8% when the 5.7% level was breached.
According to the BBC report, ONR deputy chief inspector Mark Foy said the new limit would be confirmed within the next few weeks. “Ageing is a nuclear safety issue,” he said.
Steve Thomas, professor of energy policy at the University of Greenwich, was quoted as saying: "It doesn't feel good when we come up against limits and the first thing they [the ONR] do is to move the goalposts."
The new graphite loss limit will take Dungeness B through to the start of 2020, three years before EDF Energy’s planned retirement date for the plant in 2023. This means a second increase in the weight loss limit may be requested at a later date.
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