- Site: Hinkley Point C
- IR number: 21-009
- Date: August 2021
- LC numbers: 14, 17
Executive summary
Purpose of Intervention
This intervention was conducted remotely with staff from NNB Generation Company (HPC) Ltd (hereafter referred to as NNB GenCo). It was undertaken as part of the Office for Nuclear Regulation (ONR) intervention plan, HPC Project Intervention Plan beyond J0.
The overall purpose of the intervention was to gain confidence that NNB GenCo’s human factors (HF) team has an appropriate level of oversight (and clearly defined requirements) to ensure that HF requirements are appropriately incorporated in the design of the structures, systems and components. It is important to note that the Responsible Designer (RD) is responsible for overseeing some of the supply chain and therefore NNB GenCo needs to be focused on both the activities of the RD and of the equipment suppliers.
Interventions Carried Out by ONR
I conducted a compliance inspection considering Licence Condition (LC) 14 (Safety Documentation) and LC17 (Management Systems). The focus of this inspection was to ensure that the licensee’s arrangements are adequate and have been appropriately implemented in relation to surveillance of human factors integration (HFI) into equipment designs. This is relevant ahead of bulk installation of mechanical, electrical, and heating, ventilation and air conditioning (MEH) equipment and future commissioning activities. The inspection also tested whether the HF design substantiation approach and evidence for MEH is adequate to support the human based safety claims associated with relevant equipment.
In this intervention I assessed arrangements and implementation of those arrangements against relevant good practice, which included the following ONR regulatory guidance:
- Safety Assessment Principles for Nuclear Facilities. Revision 1.
- Nuclear Safety Technical Assessment Guide: Human Factors Integration, NS-TAST-GD-058 Revision 4.
- Nuclear Safety Technical Assessment Guide: Workplaces and Work Environment, NS-TAST-GD-062 Revision 4.
- Nuclear Safety Technical Assessment Guide: Human Machine Interface, NS-TAST-GD-059 Revision 5.
- Nuclear Safety Technical Assessment Guide: Human Reliability Analysis, NS-TAST-GD-063 Revision 5.
- NS-INSP-GD-014 LC14 Safety Documentation
- NS-INSP-GD-017 LC17 Management Systems
Key Findings, Inspector's Opinions and Reasons for Judgements Made
I found that NNB GenCo has arrangements in place for undertaking surveillance of human factors integration into the equipment design. The arrangements for surveillance of the RD oversight were broadly adequate but I note that there are now challenges applying these in a timely fashion since many equipment designs are now mature and have already entered manufacture and factory acceptance testing (FAT). However, this intervention highlighted that for the pilot case, HF deliverables had not been produced by the suppliers as specified in the contractual requirements. RD and NNB GenCo surveillance arrangements had identified these shortfalls but there was no established pathway to resolve the non-delivery and therefore I was unable to gain confidence that human factors had been adequately integrate into the design. NNB GenCo has identified a potential gap between the findings of its HF surveillance and their resolution via the wider HPC arrangements for quality and supply chain management. However, NNB GenCo gave confidence it is forging a route to ensure the specified deliverables will be produced.
As part of the hot feedback I rated LC17 as green on the basis that the licensee’s surveillance arrangements had been effective but noted an action for NNB GenCo to supply minutes of the imminent meeting to agree a suitable resolution pathway. On receipt of these minutes, it is now my view that the arrangements for ensuring production of the supply chain HF deliverables and confirmation of HFI into the design are still to be confirmed and fully implemented. Therefore although, currently, there is nothing to indicate that NNB GenCo is not compliant with its LC17 duties, I have not gained confidence that HF requirements are being adequately integrated into the equipment designs in a timely fashion. This may not be concerning for some commercial off-the-shelf (COTS) equipment (where equivalent evidence of design assurance could be available). However, for novel/complex equipment which are associated with risk-significant human reliability claims in the safety case, HF design substantiation evidence must be proportionate to the nuclear safety significance. Therefore I will raise a Level 4 Regulatory Issue to monitor HFI on specific equipment items which have been identified as ‘high’ for human factors importance. This will allow ONR to track this concern prior to the installation of key equipment on the nuclear island.
Initially it appeared that the proposed HF Safety Case Design Review (SCDR) process would provide evidence to confirm that the equipment designs could be substantiated to support human based safety claims within the safety case. However, the intervention confirmed that this was not the main purpose of the SCDR reports. Although the SCDR findings may eventually contribute to the outlined HF deliverables, which will support future HPC staged safety case submissions, NNB GenCo confirmed there are wider HF activities that will confirm design suitability. These will be outlined in the updated HF Topic Route Map (not yet received by ONR). Therefore, the link between the SCDR report and safety documentation is not clear at this time. I judged that, on the evidence sampled, it was not appropriate to rate against LC14 on this occasion and will instead pursue this via normal business ahead of the next safety report submission (Summary Safety Case Document #2).
Conclusion of Intervention
Overall, based upon the judgements described above, I have concluded that an inspection rating of ‘GREEN’ is appropriate for LC17 Management Systems but will raise a Level 4 Regulatory Issue to capture the shortfalls in HF integration into the design. I judged it was not appropriate to rate against LC14 at this time since the link between the HF SCDR process and safety case documentation is not yet clear.