The Nuclear Free Local Authorities (NFLA) Scotland Forum highlights quite concerning issues that arise from the publication of the Periodic Safety Review (PSR) for the Torness nuclear reactor in Lothian.
The Office for Nuclear Regulation (ONR) has published its Project Assessment Report (PAR) and confirmed that EDF Energy Nuclear Generation Ltd has carried out an adequate periodic safety review (PSR) of the Heysham 2 and Torness nuclear power stations, justifying continued safe operations of the reactors for the period 2020 – 2030. (1)
However, EDF has not adequately addressed all of the shortfalls identified by ONR in the earlier safety assessments of other UK ageing (AGR) reactors.
NFLA notes that the PSR recommends that conditions be included in the Decision Letter with agreed timescales to address these outstanding recommendations and ONR findings. NFLA highlights these significant issues raises by the ONR in this media release.
On Control and Instrumentation (C&I) ONR does not consider that EDF have satisfactorily addressed the following findings and recommendations of earlier assessments:
- EDF should undertake a station wide review of cyber security arrangements as part of the PSR process, and clarify how cyber security issues are integrated / addressed in the equipment reliability process.
- EDF should consider including further information in future periodic safety review submissions regarding the following – Confidence of C&I ageing mechanisms; Changes in C&I ageing and obsolescence predictions since the previous PSR; The benefits that research and / or testing has had in providing an accurate understanding of the age conditioning process.
EDF says that it expects the graphite bricks in the core of the reactor at Torness to develop cracks in a similar way as Hunterston B, due to similar grades of graphite being used at each station.
Although the ONR graphite specialist was content with the evidence sampled concerning the graphite integrity, in order to demonstrate the continued fitness for purpose of the graphite core, and to demonstrate tolerance to the expected degree of core cracking and oxidation, regular inspections will be required.
NFLA has been in extensive discussion with the ONR over its concerns with the level of keyway root cracking in the graphite bricks of the Hunterston B reactors, which have been closed for some significant time now as updated safety cases from EDF are being considered by ONR. The design of the graphite moderator bricks at Torness is different from the rest of the AGR operating fleet in that it incorporates seal rings between graphite bricks. Indeed EDF states that a systematic failure of the seal rings could occur post-keyway root cracking (KWRC). This could lead to debris with the potential to challenge the ability to move or adequately cool fuel.
ONR is aware that work is ongoing to address all potential consequences of a seal ring / brick interaction. This includes stress analysis and experimental activities. The results of these activities will be incorporated within the onset of KWRC safety case. The ONR graphite specialist inspector will track the progress on these updates. NFLA will keep a close eye on these updates given the wider concerns that have been present at Hunterston B.
NFLA note that the ONR graphite specialist inspector identified that at the time of the production of the PSR report, EDF did not have a clear strategy for raising the mean active core weight loss limit (currently 14%) as it was EDF’s view that the current limit would not be challenged until ~2022. Due to the significance of this operational limit and the apparent absence of a strategy to manage the risk, the ONR graphite specialist inspector will track this issue to ensure appropriate visibility of EDF’s actions in addressing the active core weight loss limit. To address these perceived shortfalls, the ONR graphite specialist inspector will monitor the actions being taken by the licensee to mitigate any risk.
For NFLA, these issues appear to be both significant and raise real concern. Whilst it has been heavily involved in the past 18 months in calling for the Hunterston B reactor not to restart due to issues over high levels of keyway root cracking of the reactors, it remains concerned similar issues could occur in the other EDF run reactors, including Torness, Hinkley Point B and Heysham. NFLA will keep a close eye on how EDF seeks to respond to these significant issues.
NFLA Scotland Convener Councillor Feargal Dalton said:
“These safety reservations surrounding the Torness Periodic Safety Review need to be cleared up as soon as possible. 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 aging are likely to arise at Torness over coming years. NFLA will keep a very close eye on these issues and press the regulator to forensically scrutinise what look like significant weaknesses in the EDF safety case. 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 non-nuclear economy as quickly as possible.”
Ends – for more information please contact Sean Morris, NFLA Secretary, on 0161 234 3244.
Notes to Editors:
(1) Periodic Safety Review: Assessment of the Heysham 2 and Torness third periodic safety review (PSR3)