Executive summary
Date(s) of inspection: July 2024
Aim of inspection
Licence Condition (LC) compliance inspections are an essential element of ONR's intervention strategy on any nuclear site and consist of a series of inspections, each of which is intended to establish whether the licensee, NNB Generation Company (HPC) Ltd (NNB GenCo), has adequate arrangements in place for compliance with a specific LC.
The aim of this inspection is to gain assurance that NNB GenCo has adequate arrangements in place for compliance with LC19, in relation to care and maintenance of high integrity components (HIC) whilst in storage prior to their eventual installation at HPC.
The inspection is undertaken as part of a series of planned interventions in accordance with the HPC Intervention Strategy for 2024/2025 and will inform ONR's consent for the installation of HPC Unit 1 reactor pressure vessel.
Subject(s) of inspection
- LC19 - Construction or installation of new plant - Rating: Green
Key findings, inspector's opinions and reasons for judgement made
Hinkley Point C primary circuit components are designed, manufactured, installed and commissioned by NNB GenCo's supplier, Framatome. Some components including the reactor pressure vessel, steam generators and pressurisers are designated as High Integrity Components, such that strict and demanding requirements enable gross failure of these components to be discounted from the design basis. An important aspect of this requirement is the care and maintenance of these components prior to their eventual installation. This activity is managed by Framatome with oversight from NNB GenCo as an intelligent customer.
During the inspection, I sampled the following areas;
- NNB GenCo's and Framatome's care and maintenance arrangements for storage of HIC components on HPC site;
- The non-conformance process and arrangements for care and maintenance activities;
- The surveillance arrangements conducted by NNB GenCo and the Third-party inspection body; and
- Framatome’s approach to ensuring the care and maintenance technicians competency.
I also conducted a site walkdown of the Framatome storage facilities to determine the suitability of storage conditions, implementation of non-conformance mitigations and a general examination of stored components.
I considered aspects of previous shortfalls relating to the loss of humidity control and am satisfied that arrangements have been revised to prevent future occurrences and that current mitigations are appropriate.
I identified minor shortfalls relating to;
- Packaging exceeding expiration dates for which current storage conditions and activities provided suitable mitigation until technical solutions have been identified,
- Minor staining to the reactor pressure vessel external surface for which I have requested NNB GenCo to investigate and assess.
While Framatome was unable to provide details relating to inspection checks, humidity gauge calibration and records pertaining to reactor pressure vessel storage support structures, I was given assurances that these were being implemented correctly. I have requested evidence to confirm these assurances.
At the time of my inspection, and from the information I have sampled, I am content that NNB GenCo has adequate LC19 arrangements in place for the care and maintenance of high integrity components at the HPC site and that these are being implemented through the main contractor Framatome. I have raised regulatory issue RI-12138 to address the minor shortfalls described above and to provide evidence that was not available during the inspection.
Conclusion
The inspection gathered evidence over a range of areas and the overall conclusion was that the LC19 arrangements for care and maintenance of high integrity components at HPC site are adequate. Whilst I identified areas for improvement in some care and maintenance activities, I judge the shortfalls to be minor. Therefore, I consider that, in accordance with ONR guidance on the application of inspection ratings, a GREEN rating is appropriate for this inspection.