UK-based EDF Energy said on 7 June it had decided to move Dungeness B nuclear power station in Kent into the defueling phase with immediate effect. Since September 2018 the station has been in an extended outage in which EDF has been managing a range of unique, significant and ongoing technical challenges that are not found at the other six advanced gas-cooled reactor (AGR) power stations. Although many have been overcome, new detailed analysis has further highlighted additional station-specific risks within some key components, including parts within the fuel assemblies, EDF said.

As a result, EDF has taken a decision not to restart the plant but to move it into the defueling stage. Its closure in 2018 means the plant ran for 10 years longer than its original design life, and in line with expectations when it was acquired by EDF in 2009. Since it came online in 1983, Dungeness B has helped the UK avoid the emission of almost 50m tonnes of carbon dioxide.

Construction began at Dungeness B in 1967. It was to be the first of a new wave of UK nuclear power stations and has a design not reproduced anywhere else in the UK fleet. The plant connected to the electricity grid in 1983. The original design life was 2008 and this was extended following investment in the plant at that time and subsequently. 

John Benn, Station Director at Dungeness B said: “This power station has been a cornerstone of life in Kent for decades. It is a very special place and the team has a real sense of family – we are part of the community. EDF has had to make a hard decision – but it is the right one. It gives our teams, our community and our business a clear understanding of the future.”

He added: “I’m enormously proud of everything the team at Dungeness has achieved. Our low-carbon electricity has helped Britain over the past four decades and we have provided this part of Kent with vital jobs for generations. This marks the beginning of the next chapter in this station’s story. We will now plan the defueling operations, a job we expect will take several years, and one that provides ongoing opportunities for our staff and their specialist skills.” Dungeness B has around 500 staff and 250 contractors working on site.

Dungeness B is one of a fleet of seven AGRs that, whatever the weather conditions, have reliably provided around 20% of the UK’s power supply over the last four decades. In 2018 the site’s two reactors started a planned period of maintenance, inspections and refuelling. Initial works highlighted problems with the site’s main steam line and corrosion in pipework, both of these were resolved through major investment. EDF also undertook deeper analysis of material conditions within the plant’s boilers, which at Dungeness are contained within the reactors. The investigation found that components, which cannot be replaced, had changed faster than anticipated.

Image: Dungeness B nuclear power station in Kent