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EDF’s failing nuclear reactors in UK

  1. NuclearNews No 126 20 June 20,Hinkley’s sister reactors at Hunterston B (all 4 reactors have operated since 1976) have both been closed for much of the past two years. Reactor 3 has been offline for more than two years, since March 2018. Reactor 4 was first shutdown on 2nd October 2018 but was allowed a trial operation between August 2019 and 10th December 2019. The safety case for restarting Reactor 3 was finally been submitted to the Office for Nuclear Regulation (ONR) for its assessment in mid-May and for Reactor 4 on 29th May. EDF now says it is hoping that Reactor 3 can restart on 13th July 2020 and Reactor 4 on 27 July 2020.

EDF may be hoping to restart the two reactors in July but there are increasing concerns regarding revelations the graphite cores have begun to crumble as cracks spread. At least 58 fragments and pieces of debris have broken off the graphite bricks that make up the reactor cores. According to the Office for Nuclear Regulation (ONR) there is “significant uncertainty” about the risks of debris blocking channels for cooling the reactor and causing fuel cladding to melt. Such a disaster could result in a radiation leak and contamination right across the central belt of Scotland. Small wonder then that many local residents are pressing ONR to refuse EDF permission to restart these decrepit 44-year old reactors. (3)

EDF says it has spent more than £200 million on tests, inspections and creating quarter-scale models of the reactor cores that are shaken to mimic a quake to try to prove that the graphite is safe. EDF hopes the new safety cases will be approved in July to allow for six months of operation. That may pave the way for approval for Hinkley Point B with “pretty much the same safety case”.

£200 million may seem like a lot of money, but it’s only about one reactor’s income for one year, so if it helps EDF keep its fourteen AGRs generating for longer it will have been well worth it for the Company.

But, like Hinkley Point B, the two Hunterston reactors are due to shut for good in 2023. EDF chose not to enter the two Hunterston B reactors into the capacity market auction for the period October 2022 to September 2023. Although Hinkley Point B entered into the auction “it exited above the clearing price and therefore did not get an agreement. The revenues at the clearing price did not provide sufficient reward to take on the risk of penalties arising from non-delivery” (4) – probably indicating a lack of confidence at EDF that any of the 4 reactors will make it as far as September 2023.

Another signal that minds at EDF are switching from generation to decommissioning is the fact that the generator has announced plans to submit scoping requests to North Ayrshire Council ahead of planning applications for waste facilities to support future decommissioning activities.

As part of the preparations for decommissioning, EDF is planning to build a new intermediate level waste (ILW) store and two waste processing facilities on the B site with applications for planning permission submitted by early 2021, following a period of consultation with a range of stakeholders.

A final decision has still to be taken on the best route for storage of ILW from Hunterston B and EDF is still looking at a range of options including the shared use of the Hunterston A ILW store. But to ensure the site can move into de-fuelling with no unnecessary downtime, applications are being lodged now to speed up the process should EDF decide to build a new store.

Discussions are also reported to be underway between BEIS, EDF Energy and the NDA, to examine the future decommissioning of the AGR fleet when it is time for the reactors to come off line. As yet no decisions have been made, and those discussions continue.

But it’s not just Hunterston B and Hinkley Point B which are causing sleepless nights for EDF. As Emily Gosden, writing in The Times, points out, all of “the AGRs are scheduled to close permanently between 2023 and 2030, but all also have graphite cores that bring their lifespans into doubt.”

  1. All the AGRs will eventually exhibit some form of cracking towards the end of life says Richard Bradfield, chief technical officer for generation at EDF Energy: “There are two irreplaceable components on an advanced gas-cooled reactor: the graphite and the boilers.”
  2. Hartlepool and Heysham 1 Hartlepool and Heysham 1 are both due to shut-down in 2024. Although they were entered into the capacity market auction for October 2023 to September 2024 and EDF says “we are confident they will operate to their scheduled closure date of 2024, they exited above the clearing price and therefore did not secure agreements. The revenues at the clearing price did not provide sufficient reward to take on the risk of penalties arising from non-delivery.” (5)

Heysham 1 Power Station was recently served with an improvement notice by the Office for Nuclear Regulation after contravening safety regulations regarding the pressure systems of their nuclear reactor. The notice was served on June 4 after shortfalls were discovered in the examination and inspection of the Reactor 1 pressure vessel. Nuclear reactor pressure vessels feature hundreds of sealed penetrations which must be routinely inspected to ensure they are free from defects. Out of the 600 penetrations in one of the reactors ONR found that EDF Energy had failed to examine 11 penetrations within the intervals specified in the written maintenance scheme. EDF must comply with the improvement notice served to them by the ONR and complete the 11 overdue examinations by December 18, 2020. (6)

Dungeness B On 27 August 2018 Dungeness B shut down Reactor 22 for its planned statutory outage. On 23 September 2018 Reactor 21 was also shut down for the planned double reactor outage. Both reactors have been shut since. The regular inspections on the reactors in Kent in late summer 2018 identified the need for repairs on steam pipes. The inspections showed that seismic restraints, pipework and storage vessels associated with several systems providing a safety function were found to be “corroded to an unacceptable condition” according to ONR. (7) Measures are being taken to eliminate the corrosion, including the upgrading of more than 300m of pipeline associated with reactor cooling systems and renewal of numerous seismic pipework supports and remediation of carbon dioxide storage vessels. On 26th February 2020 EDF Energy announced further extended outages at the two reactors The Dungeness B21 reactor was due to come back online on April 20 but the outage was extended to July 18. The Dungeness B22 unit was previously due back online on May 2 but that was extended to July 8. The dates given now are 21st September and 11th September. (8)

  1. The boiler design at Dungeness was “very different” to the other AGRs and probably would be the life-limiting factor for the plant. However, EDF says the issues are “manageable” and that the company aimed to present a safety case shortly to seek to restart in September. (9)
  2. Torness and Heysham 2 The Office for Nuclear Regulation (ONR) published its Project Assessment Report which allows Torness and Heysham 2 to continue operating for the period 2020 – 2030. (10) The Ferret website reported that cracks in the graphite core are now expected to start appearing six years sooner than previously thought (11)
  3. ONR said that the cracking could cause debris to inhibit vital cooling of highly radioactive reactor fuel beginning as soon as 2022 rather than 2028. It said Torness and Heysham 2 will be able to keep operating until 2030 – but only if inspections to check for cracks are intensified. ONR promises to “robustly challenge” the plant’s operators, EDF Energy, to ensure that it “remains safe”.
  4. Campaigners fear that Torness will become increasingly unsafe, and warn it may have to close down sooner than expected. EDF, however, insists that the station will keep generating electricity safely until 2030. NFLA has called on ONR to keep Torness under close scrutiny. “These safety reservations surrounding the Torness periodic safety review need to be cleared up as soon as possible,” said the group’s Scotland convenor, SNP Glasgow councillor, Feargal Dalton. “Whilst EDF is having to spend large resources trying to persuade the regulator that it is safe to restart the Hunterston B reactors, this report emphasises that similar issues with ageing are likely to arise at Torness over coming years.” Councils would press ONR “to forensically scrutinise what look like significant weaknesses in the EDF safety case,” Dalton added. “In the meantime, the Scottish Government should start discussions about a ‘just transition’ for the workers at both Hunterston and Torness so that Scotland can move to a safe, sustainable and nonnuclear economy as quickly as possible.”

ONR made nine recommendations to remedy major “safety shortfalls” at Torness and Heysham 2 and raised 41 minor matters with EDF. These include “weaknesses” in health reviews, as well as issues with “structural integrity”, “corrosion management” and “cyber security”.

Although no cracks have yet been detected, ONR inspectors pointed out there was a significant difference in the design of Torness and Heysham 2 compared to that of Hunterston. The newer stations have seal rings between the graphite bricks that make up the reactor core. ONR quoted EDF saying that there could be “a systematic failure” of the seal rings after cracking. “This could lead to debris with the potential to challenge the ability to move or adequately cool fuel,” said ONR. “If keyway root cracking predictions are realised, then the safety case is unlikely to remain robust for the next ten years periodic safety review period,” observed ONR inspectors.

It could, in fact, be cheaper to build new renewable capacity rather than continue to operate these ageing reactors. This could soon be the case with Torness, especially if it has to keep being turned on and off to inspect the graphite core. Scotland clearly needs to be prepared for the possibility that Torness might be forced to close not long after 2022.

  1. Flexible Return Dates
  2. Paul Brown asked EDF “At what point do you cut your losses and close the stations permanently?” but failed to get a sensible reply. On Dungeness B it said: “For the past two years we have undertaken a major investment programme at Dungeness to secure the station’s longer-term future. Since the start of the year we have made great progress in tackling some of the complex problems our works identified. However we still have further engineering works to complete, and a detailed safety case to finalise, before we ask for restart approval from our regulator. Our present position for estimated return to service is 11 September for Reactor 22 and 21 September for Reactor 21.”

Stephen Thomas, professor of energy policy at the University of Greenwich, commented on the constantly postponed start-up dates for the ageing reactors: “It is clear, given that shutdowns expected to take two months are now expected to take two years or more, that EDF has found huge unanticipated problems”, he said. “It is hard to understand why, when the scale of the problems became clear, EDF did not cut its losses and close the reactors, but continues to pour money into plants to get a couple more years of operation out of plants highly likely to be loss-makers. It is depressing that ONR, which has a duty to keep the public informed on such important issues, chooses to hide behind bland statements such as that it will take as long as it takes, and that it will not comment on EDF’s decisions.” (12)

June 20, 2020 - Posted by | politics, UK

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