Office for Nuclear Regulation

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Compliance inspection of geotechnical records for construction of twin EPR units at Hinkley Point C

Executive summary

Purpose of Intervention

This was a planned inspection of NNB Generation Company (HPC) Ltd.’s (NNB GenCo) Hinkley Point C (HPC) project, specifically to consider geotechnical records being produced from the construction earthworks, and how this information will feed into future iterations of the safety case and support lifetime records of the plant. This inspection forms part of the planned intervention strategy for the New Reactors Division (NRD) of the Office for Nuclear Regulation (ONR).

The inspection was in accordance with the planned inspection programme contained in the HPC 2019 civil engineering intervention strategy. The inspection was undertaken by three ONR inspectors from the civil engineering and external hazards specialism.

Interventions Carried Out by ONR

On 1-2 May 2019, I (the civil engineering and external hazards nuclear safety inspector) undertook a site licence condition (LC) compliance inspection at HPC in relation to the geotechnical data arising from the on-going earthworks, focussing on the works associated with the cooling-water pumping station (CWPS) and nuclear island (NI) common raft (CRX). The inspection considered the following LCs:

The purpose of the inspection was to:

The intervention was performed in line with ONR's guidance requirements (as described in our technical inspection guides) in the areas inspected.

Explanation of Judgement if Safety System Not Judged to be Adequate

Not applicable – this was not a system-based inspection.

Key Findings, Inspector's Opinions and Reasons for Judgements Made

LC6 (Documents, records, authorities and certificates) – I sampled records generated by the licensee to demonstrate compliance with LC19 including surveillance sheets for construction quality-related activities (QRAs) and other witness points related to CWPS and CRX. I also sampled various records of change where the ground conditions were different to those expected including non-conformance records (NCRs) and field change requests (FCRs). The inspected records were complete with clear traceability to associated documents. Overall, I am content that the licensee has appropriate arrangements in place for producing adequate records relating to the earthworks and I judge a green rating (no formal action) is appropriate.

LC19 (Construction or installation of new plant) – From my observations, the licensee appears to have adequate arrangements for controlling the construction of the earthworks at HPC, and is implementing these arrangements as demonstrated by the records sampled. Records will be collated and delivered to the licensee via Life-Time Quality Records (LTQRs) and End of Construction Status Reports (ECSRs). These will inform the production of six interim geological, geotechnical and hydrogeological reports for the HPC site, the first of which is being drafted. These reports will be used to update the extant geotechnical interpretative report (GIR), and inform future safety cases.  Whilst I am aware of a broader ONR regulatory issue (RI 7042) with respect to the production of LTQRs, I am content with the licensee’s evidence provided during my inspection and consider the licensee’s approach broadly consistent with relevant good practice (RGP). I therefore judge a green rating (no formal action) is appropriate.

Conclusion of Intervention

After considering the evidence sampled during the inspection for LCs 6 and 19, I judge that the licensee is compliant with its legal duties relating to the generation of documents and records for the earthworks associated with construction of the new plant at HPC.

10. I judge that there are no findings from this inspection that could significantly undermine nuclear safety at HPC. No additional regulatory action is needed over and above the planned interventions at HPC as detailed in the 2019 intervention strategy, and management of extant regulatory issues.