Date(s) of inspection
- September 2023
Aim of inspection
The aim of the inspection was to examine the adequacy of NNB Generation Company (HPC) Ltd’s (NNB GenCo) implementation with its Licence Condition (LC) 12, LC14 and LC21 compliance arrangements to gain confidence in:
- traceability of requirements from the safety case claims on the polar crane through to the programme of commissioning tests;
- commissioning documentation provided by a Design, Manufacture, Install and Commission (DMIC) contractor and the level of surveillance from the licensee on that documentation;
- whether the proposed programme of commissioning activities is adequate to gather the required evidence to support the operational safety demonstration;
- whether the commencement and progression of the commissioning phase for the polar crane is adequately controlled; and
- whether the commissioning phase activities for the polar crane are appropriately understood and will be managed such that nuclear safety related risks will be tolerable and reduced to as low as reasonably practicable.
The polar crane was selected for inspection by ONR due to its importance to nuclear safety and because it is one of the first items of equipment to be commissioned at Hinkley Point C (HPC).
ONR has a separate inspection related to polar crane commissioning (CM8), which is planned to be a site-based inspection conducted during commissioning of the polar crane in the reactor building. The purpose of this office-based inspection was to gain confidence in the adequacy of the proposed commissioning activities to support nuclear safety and the traceability of requirements from the safety case.
Subject(s) of inspection
- LC12 – Duly authorised and other suitably qualified and experienced persons – Rating: Green
- LC14 – Safety documentation – Rating: Green
- LC21 – Commissioning – Rating: Green
Key findings, inspector’s opinions and reasons for judgement made
Overall, we judged that there was adequate traceability of requirements from safety functions through to commissioning tests. However, we identified some shortfalls in traceability for requirements which are demonstrated through a combination of both testing and analysis and in definition of performance criteria for the commissioning tests. We have raised a level 4 regulatory issue for the licensee to address these shortfalls prior to commissioning of the polar crane.
Regarding NNB GenCo’s approach to oversight and surveillance of the contractor who is supplying and commissioning the polar crane, the licensee recognised that this requires further development. Nevertheless, we judged that NNB GenCo’s proposal for 100% surveillance is a suitable planning assumption at this stage.
The complete programme of commissioning tests for the polar crane is still under development. However, we considered that NNB GenCo is following a logical and systematic approach to developing this programme. This should ensure it gathers the required evidence to support the operational safety demonstration.
NNB GenCo has established a system ownership panel to provide working level control over the commencement and progression of the commissioning phase for the polar crane. We were satisfied with NNB GenCo’s proposal.
We concluded that the commissioning phase activities for the polar crane are appropriately understood by NNB GenCo, so that they can be managed such that nuclear safety risks will be adequately controlled.
We judged that relevant good practice was generally met. We judged that the shortfall in terms of requirements traceability was relatively minor when compared with appropriate benchmarks. We therefore judged an ONR inspection rating of Green (no formal action) was appropriate against Licence Conditions 12, 14 and 21.
We raised a level 4 regulatory issue for NNB GenCo to address the identified shortfall in traceability of requirements which are demonstrated through a combination of both testing and analysis and in the definition of performance criteria for commissioning tests.