- Site: Heysham 2
- IR number: 21-115
- Date: November 2021
- LC numbers: 10, 23, 24, 27, 28
Executive summary
Purpose of Intervention
The purpose of this intervention was to undertake a planned system based inspection of the reactor safety system at EDF Nuclear Generation Limited’s Heysham 2 power station in line with the planned inspection programme in the Heysham 2 Intervention Strategy for 2021/22.
Interventions Carried Out by ONR
The focus of this inspection, which was carried out by two control and instrumentation inspectors, was the reactor safety system, and in particular the trip parameters. This system continuously monitors conditions on the reactor and initiates a reactor trip if specified reference levels of any measured parameters are exceeded.
The objective of the inspection was to examine, on a sample basis, the adequacy of implementation of the safety case against the following licence conditions (LC), which are all applicable provisions of the Energy Act 2013:
- LC 10 (Training)
- LC 23 (Operating Rules)
- LC 24 (Operating Instructions)
- LC 27 (Safety Mechanisms, Devices and Circuits)
- LC 28 (Examination, Inspection, Maintenance and Testing)
The intervention was performed in line with ONR's guidance requirements (as described in our technical inspection guides) in the areas inspected.
Explanation of Judgement if Safety System Not Judged to be Adequate
Not applicable.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
Based on the information sampled during the inspection, we concluded the following in relation to each licence condition:
LC 10 (Training) – We examined training records for several personnel who carry out operations and maintenance activities on the reactor safety system, from which we were satisfied that EDF NGL has made and implemented adequate arrangements for suitable training of those on site who have responsibility for operations which may affect safety. We were also satisfied with EDF NGL’s arrangements for supporting individuals who are still completing the required training for their roles, such as a maintenance technician and system engineer that we sampled in our review of training records. Although we identified that a duly authorised person training item for a CCR Supervisor had expired 2-days previously, the appropriate reauthorisation was promptly obtained. We have therefore assigned a rating of ‘Green’ (no formal action) for LC10 compliance.
LC23 (Operating Rules) - We examined the safety case, technical specifications and other supporting documents for the reactor safety system in order to determine whether suitable limits and conditions were identified. Based on the evidence sampled, we were satisfied that EDF NGL has identified suitable limits and conditions in the interests of safety as claimed in the safety case, and that these were clearly set out within technical specifications. We have therefore assigned a rating of ‘Green’ (no formal action) for LC23.
LC24 (Operating Instructions) - We sampled a number of station operating instructions and check-sheets that implement operating rules covered by surveillance requirements within technical specifications, and also a number of maintenance instructions and check-sheets from our LC28 enquiries. Although we identified a small number of minor issues relating to tolerances values in maintenance instructions and/or check-sheets, our overall judgment based on the evidence sampled was that required limits and conditions for operations that may affect safety were implemented via clear working instructions. We have therefore assigned a rating of ‘Green’ (no formal action) for LC24.
LC 27 (Safety Mechanisms, Devices and Circuits) – We carried out a plant walk-down to view parts of the reactor safety system, discussed EDF NGLs arrangements for manging system health, and also sampled system health records. Although formal plant walk-downs had not been carried out at the recommended frequency in the past year, we were satisfied that EDF NGL’s Independent Nuclear Assurance regulator was working with the plant to address this matter. Based on the evidence sampled, our overall judgment was that suitable and sufficient safety mechanisms, devices and circuits were properly connected and in good working order. We have therefore assigned a rating of ‘Green’ (no formal action) for LC27.
LC 28 (Examination, Inspection, Maintenance and Testing) – We sampled several completed maintenance records and held discussions with staff responsible for arranging and delivering these maintenance activities. Based on the evidence sampled, we were satisfied that adequate arrangements to ensure regular and systematic examination, inspection, maintenance and testing of plant which may affect safety were implemented and being applied in a timely manner. We have therefore assigned a rating of ‘Green’ (no formal action) for LC28.
LC34 (Leakage and Escape of Radioactive Material and Radioactive Waste) – This was not considered in this particular intervention as the reactor safety system does not contain radioactive material or radioactive waste.
Conclusion of Intervention
Based on the evidence sampled during this system based inspection, we judged that the Heysham 2 reactor safety system adequately fulfils the requirements of the safety case and achieves its safety functional requirements.
We did not identify any findings that could significantly undermine nuclear safety, and no formal regulatory actions were raised. For the small number of issues that we identified, we are content for EDF NGL to address these under their own arrangements. The intervention findings were shared and accepted by EDF NGL as part of normal inspection feedback
Based on the evidence sampled, we judged the overall inspection rating to be ‘Green’.