Executive summary
Date(s) of inspection:
- December 2023
Aim of inspection
The aim of the Heysham 2 (HY2) Post Trip Sequencing Equipment (PTSE) system based inspection (SBI) was to confirm that the:
- PTSE is able to meet the nuclear safety functional requirements defined in the station’s safety case.
- PTSE arrangements in relation to the following Licence Conditions (LCs), which are applicable provisions of the Energy Act 2013, are being correctly implemented:
- LC10: Training.
- LC23: Operating Rules.
- LC24: Operating Instructions.
- LC27: Safety Mechanisms, Devices and Circuits (SMDCs).
- LC28: Examination, Inspection, Maintenance and Testing (EIMT).
This was achieved through a sample based inspection of associated arrangements, a plant walkdown, and discussions with various stakeholders, (e.g. operators, maintainers, engineers, and training administrators).
This inspection was performed in line with Office for Nuclear Regulation’s (ONR’s) guidance requirements, which are described in our technical inspection guides (TIGs).
It is important to note that it is not the role of an SBI to challenge claims and arguments made by the safety case, as these are assumed to be robust.
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: AMBER
Key findings, inspector's opinions and reasons for judgement made
The key findings of our SBI of the HY2 PTSE are:
- LC 10 – Training: We examined the training records of several personnel involved with the oversight and maintenance of the PTSE and judged that they were suitably qualified and experienced personnel (SQEP). We also reviewed PTSE training material and found its scope and contents to be appropriate. However, we advised that a PTSE system handover document (SHD) and a mentor guide for the Y train system engineer (SE) are produced as soon as practicable. We therefore assigned an IIS rating of Green (no formal action) for LC 10.
- LC 23 – Operating rules: We reviewed the post trip cooling plant technical specification (tech spec) (5.3.4), the associated tech spec commentary (C5.3.4) and the associated tech spec compliance schedule (S5.3.4) and discussed their application with a central control room supervisor (CCRS). As a result, we judged the aforementioned to be clear and straightforward to follow. We also confirmed that the associated surveillance requirements (SRs) were being undertaken as required. We therefore judged that compliance was being achieved with the PTSE operating rules specified in the safety case. We therefore assigned an IIS rating of Green (no formal action) for LC 23.
- LC 24 – Operating instructions: We examined the main station operating instructions (SOIs) associated with the PTSE and discussed their application with a CCRS. As a result, we judged that adequate operating instructions were in place to support PTSE operations. We therefore assigned an IIS rating of Green (no formal action) for LC 24.
- LC 27 – SMDCs: During the SBI we reviewed several engineering, operating, and maintenance documents, undertook a plant walkdown and spoke to several stakeholders. As a result, we judged that the PTSE was connected correctly, was in working order, and was being adequately maintained. We also judged that PTSE configuration was being adequately controlled and that adequate numbers of spares were available. However, we did provide regulatory advice to re-emphasise to maintenance personnel the importance of ensuring that access to PTSE cubicles is appropriately controlled in accordance with HY2’s security arrangements. It should be noted that we did not consider that the above issue posed an immediate or significant threat to nuclear safety. We therefore assigned an IIS rating of Green (no formal action) for LC 27.
- LC 28 – EIMT: We reviewed several PTSE plant item operating instructions (PIOIs) / plant item maintenance instructions (PIMIs) and the associated work order cards (WOCs) and checksheets. On the whole, we considered that the associated tasks had been adequately defined; however, we did advise areas where enhancements could be made. Whilst the majority of evidence we sampled indicated that the PTSE was being adequately examined, inspected, maintained, and tested, we considered that the identified unapproved practice of maintenance technicians (MTs) declaring PTSE cubicle fans to be operational without checking them constituted a systematic failure to implement compliance arrangements. As a result, we considered that an Amber (seek improvement) IIS rating for LC 28 was initially warranted however the issue was promptly addressed. As a result, we were content that no further regulatory intervention was required.
Conclusion
From the evidence sampled during this SBI against LC 10, 23, 24, 27 and 28, we judged that the PTSE is able to fulfil its safety duties (safety functional requirements) in line with the safety case.
There were no intervention findings that could significantly undermine nuclear safety at HY2 and, at present, we consider that no additional regulatory action is needed over and above the interventions currently planned at HY2, as set out in the HY2 IIS, which will continue as planned.
However, whilst the majority of evidence we sampled indicated that the PTSE was being adequately examined, inspected, maintained, and tested, we consider that the identified unapproved practice of MTs declaring PTSE cubicle fans as being operational without checking them constitutes a systematic failure to implement compliance arrangements, and as a result we considered that an overall Amber (seek improvement) inspection rating for the SBI was warranted however the issues were promptly remedied negating the need to seek further improvement.