Executive summary
Date(s) of inspection:
- February 2025
Aim of inspection
This is a System Based Inspection (SBI) of EDF Energy Nuclear Generation Ltd.’s (NGL’s) Sizewell B Power Station Dry Fuel Store, undertaken as part of the planned intervention strategy for the Operating Facilities Division (OFD) of the Office for Nuclear Regulation (ONR). The safe transfer and storage of spent nuclear fuel is key to Sizewell B nuclear safety fundamental principles of ensuring the exposure of operators and the general public to radiation are kept as low as reasonably practical.
The aim of the SBI was to establish whether the safety systems, structures and components associated with dry fuel storage activities at Sizewell B are able to adequately fulfil their safety duties (safety functional requirements), in line with claims made within the safety case.
Subject(s) of inspection
- LC10 - Training - Rating: GREEN
- LC23 - Operating rules - Rating: GREEN
- LC24 - Operating instructions - Rating: GREEN
- LC27 - Safety mechanisms, devices and circuits - Rating: GREEN
- LC28 - Examination, inspection, maintenance and testing - Rating: GREEN
- LC34 - Leakage and escape of radioactive material and radioactive waste - Rating: GREEN
- Overall Inspection Rating - Rating: GREEN
Key findings, inspector's opinions and reasons for judgement made
The key findings of the systems based inspection (SBI) for the Sizewell B (SZB) dry fuel store (DFS) safety systems and structures (SSS) are:
LC 10 – Training: I examined how operators and maintainers were deemed to be suitably qualified and experienced personnel (SQEP), and adequately trained, to undertake DFS SSS examination, inspection, maintenance and testing (EIMT) activities and considered that the associated arrangements were fit for purpose. I sampled the training records of a system engineer (SE), fuel route engineer and Holtec technician who had recently been involved with the operation and maintenance of DFS SSS equipment and found that all had completed the essential training to enable them to fulfil their role.
LC 23 – Operating rules: I reviewed several DFS SSS related technical specifications (Tech Specs), associated commentaries and a surveillance programme (SP), and discussed their application with operators. As a result, I considered the Tech Specs, associated commentaries and SP were clear in implementing the limits and conditions from the safety case and straightforward to follow.
LC 24 – Operating instructions: I examined the main station operating instructions (SOIs) and quality plans (QPs) associated with the DFS SSS and discussed their application with operators. As a result, I judged that they were logical and easy for operators and maintainers of the SSS to follow to ensure compliance with the limits and conditions set out in the Tech Specs, even under high workload scenarios.
LC 27 – Safety mechanisms, devices and circuits (SMDCs): I reviewed several engineering, operating, and maintenance documents, undertook a plant walkdown and spoke to several stakeholders. As a result, I judged that the DFS SSS were properly connected and in working order.
LC 28 – Examination, inspection, maintenance and testing (EIMT): I examined several DFS SSS plant operating instructions (POIs) and the associated work order cards (WOCs) and check sheets. On the whole, I considered that the associated tasks had been adequately defined; however, I did highlight areas where enhancements could be made. I also considered that, overall, the tasks appeared to have been carried out as specified. I, therefore, judged that the DFS SSS were being adequately examined, inspected, maintained, and tested.
LC 34 – Leakage and escape of radioactive material and radioactive waste: I sampled the arrangements of the DFS to ensure that the SSS were not leaking radioactive materials, liquids, sludges or gases and that the containment provided by the SSS is and will continue to be adequate. I considered that these arrangements have been appropriately defined and were understood by the relevant SEs. I, therefore, considered that the sampled evidence indicates that the DFS SSS are capable of avoiding leakage and escape of radioactive material and radioactive waste.
Conclusion
From the evidence sampled during this SBI against LC 10, 23, 24, 27, 28 and 34 I judged that the DFS SSS are able to fulfil their safety duties (safety functional requirements) in line with the safety case. I therefore judged the ONR inspection rating for this inspection to be Green (No formal action).
There were no intervention findings that could significantly undermine nuclear safety at SZB and, at present, I consider that no additional regulatory action is needed over and above the interventions currently planned at SZB, which will continue as planned.