Coincident with the EDF announcement that Dungeness B nuclear power station will stay open for 10 years beyond its scheduled closing date of 2018, members of the Rye Emergency Action Community Team, Anthony Kimber, Mike Slavin, Granville Bantick and John Holbrook, had a pre-planned visit to the Station. This was part of an ongoing programme to consider all those risks, which might impact on the community of Rye.
After thorough safety briefings, there was a very informative tour, which took in the main parts of the installation, expertly guided by EDF’s Sarah Mayberry. During the tour, REACT saw work underway to dismantle the neighbouring Dungeness A station, which was decommissioned in 2006. At the end, REACT had a very open meeting with Station Director, Martin Pearson.
It was explained that the building of Dungeness B as a prototype station began in 1965, with electricity generated in 1983. It now employs 550 people and six apprentices, plus 200 contract staff. The station had been scheduled to close in 2008, but its then operator, British Energy, extended its life by 10 years to 2018. The nuclear authorities had now just agreed that EDF could extend its life to 2028. It generates enough power for around 1.5m homes.
REACT was interested in the engineering assessments which lay behind the extension of operation to 2028. By way of explanation, the two Advanced Gas-cooled Reactors at Dungeness B incorporate thousands of graphite bricks. This graphite core acts as a moderator to slow the neutrons sustaining the nuclear reaction. Over time the graphite cracks and suffers loss of mass. This is well known and anticipated within set safe margins. From a continuous programme of monitoring, inspection and physical sampling of the graphite core, its state is carefully monitored. Extensive modelling has provided the data to allow EDF to increase safely the graphite weight degradation limits from 6.2% to 8%, allowing longer service time.
Pearson explained that “his number one priority was safety. Life extension, which has been approved by the Office of Nuclear Regulation, means the station will continue to provide hundreds of skilled jobs and provide …………more than £40m to the local economy.”
Ministers have reported that the life extension at Dungeness will bridge the power generation gap until after 2023, when the new EDF station will come on stream at Hinkley Point in Somerset.
With the conversation turning to risks, Pearson explained that lessons had been learnt from the 2011 Fukushima nuclear disaster. Although a tsunami type risk was low, there could be sea flood risk aggravated by tidal surge. To mitigate this there has been investment in additional rock protection on the foreshore, a 1.5m perimeter flood defence wall, additional resilience measures for its control systems and additional contingency support for its vital sea-water cooling plant.
Although built on shingle, the station is securely tethered to deep concrete foundations, which meet rules designed to handle seismic movement. To counter the terrorist threat, there are significant physical security measures in place.
This was a valuable visit, enabling REACT members to see the engineering in place at Dungeness, the considerable safety systems in place and to hear for themselves about the risks of running a nuclear plant at Dungeness.