Executive summary
Date(s) of inspection:
- February 2023
Aim of inspection
The purpose of the inspection was to gain confidence that the licensee, NNB Generation Company (HPC) Limited (NNB GenCo), has sufficient oversight of its contractor, Comeca, for the manufacture and test of the low voltage (LV) switchgear and associated priority actuation and control system (PACS), through adequate implementation of its Licence Condition (LC) 12, 14 and 17 compliance arrangements. This included gaining confidence in the application of the PACS diversity as low as reasonably practicable (ALARP) report, in particular how the arrangements claimed in the report to ensure adequate diversity between the PACS (A) and PACS (B) have been applied in practice by Comeca.
LC 12 (Duly authorised persons and other suitably qualified and experienced persons) requires a licensee to ensure that anyone carrying out work that may affect nuclear safety on the site is a suitably qualified and experienced person (SQEP). This includes all of the supply chain of the site and, where appropriate, off-site work by contractors and vendors, wherever in the world they happen to be.
LC 14 (Safety documentation) requires that the licensee shall make and implement adequate arrangements for the production and assessment of safety cases consisting of documentation to justify safety during the design, construction, manufacture, commissioning, operation and decommissioning phases of the installation.
LC 17 (Management systems) requires a licensee’s quality management arrangements to robustly encompass all work carried out for the site, including by contractors - whether as an on-site contractor or as a vendor of products and services.
I reviewed each stage of manufacture, from goods inwards to completed LV switchgear and associated PACS, and testing. At each stage, I sought evidence that demonstrated whether NNB GenCo has sufficient oversight of Comeca, in addition I sought evidence that demonstrated the diversity requirements set out in the ALARP report are being adequately implemented. I used this evidence to assess NNB GenCo's control of Comeca and whether the diversity arrangements for PACS reduces risk to ALARP.
Subject(s) of inspection
- LC 12 - Duly authorised and other suitably qualified and experienced persons - rating: Green
- LC 14 - Safety documentation - rating: Green
- LC 17 - Management systems - rating: Green
Key findings, inspector's opinions and reasons for judgement made
Based on the evidence presented, areas of good practice were identified relating to:
- the adequate quality processes in place to control and record LV switchgear manufacture and how PACS diversity is achieved;
- the understanding demonstrated by Comeca and NNB GenCo of the PACS diversity requirements;
- a robust process for ensuring specified components for switchboards and PACS were assigned to the appropriate assembly and that all components could be traced; and
- the improvements made during switchgear manufacture, in particular the moulded resin blocks.
The following minor shortfalls were identified:
- poor housekeeping was observed within the production area and I will be seeking assurances that this has been addressed during my routine engagements;
- portable test equipment was identified that was used across multiple test areas and was therefore not diverse - NNB GenCo and Comeca committed to ensuring diverse portable test equipment was available and I will track this through routine engagements;
- potential error traps in how the test staff interfaced with the test software were identified and I will track resolution of this through routine engagements;
- poor attention to detail in some areas of manufacture were noted and Comeca and NNB GenCo committed to resolving these; and
- issues were identified with an end of manufacturing report (EoMR) and the PACS equipment list that could introduce error traps for users of the documents - I have raised a regulatory issue to track this.
Conclusion
I judge that an intervention rating of GREEN is appropriate for LCs 12, 14 and 17 because I found NNB GenCo to be compliant with its legal duties with only minor areas for further improvement.
LC12 - Based on my sampling of the relevant training records, the implementation of annual audits of Comeca’s quality management system (QMS) reviewing staff training records and the displayed understanding of diversity requirements by Comeca staff, I am content that NNB GenCo and Comeca have adequate arrangements for ensuring only SQEP staff carry out work that may affect safety. I therefore consider a rating of GREEN is appropriate.
LC14 - Overall, the arrangements in place to maintain PACS diversity for all stages of manufacturing and testing were considered adequate. In addition, the arrangements in place to ensure the LV switchboards are manufactured and tested in line with their safety case requirements were appropriate.
I found shortfalls in the PACS equipment list and a follow up document (FUD) contained within the EoMR. However, I do not consider these shortfalls to be significant and I am content the arrangements in place to manage diversity requirements and maintain equipment (component) diversity and human diversity (where claimed) for all stages of manufacturing and testing for each LV switchgear are adequate.
Based on my sampling of evidence provided by NNB GenCo and Comeca, I have found areas of good practice, particularly in the staff's knowledge of the PACS diversity requirements. However, I found shortfalls in the PACS equipment list and EoMRs that had the potential to lead to error traps. As a result of this, I have raised a regulatory issue regarding the updating of the PACS equipment list and EoMRs. However, I do not consider this shortfall to be significant and I am content that the safety documentation is well understood and, where shortfalls exist, NNB GenCo is committed to remedying these issues. As such, I consider that it is appropriate to rate LC 14, safety documentation, as GREEN with minor shortfalls identified.
LC 17 – Based on my sampling of evidence provided by Comeca and NNB GenCo relating to management systems, I have found areas of good practice in the documentation, such as the use of FUDs, EoMRs and the non-conformance reporting process and its implementation.