Office for Nuclear Regulation

Quality improvement measures for the Hinkley Point C nuclear steam supply system (NSSS10)

Executive summary

Purpose of Intervention

The contract for the Hinkley Point C (HPC) nuclear primary circuit components lies with Framatome, with most of the primary circuit being fabricated at Framatome St Marcel using forgings mainly provided by Framatome Creusot Forge or Japan Steel Works.

ONR is permissioning the HPC hold point ‘Receipt of the first nuclear steam supply system (NSSS) component at site’; ONR’s judgement as to whether to allow NNB Generation Company (HPC) Ltd (hereafter referred to as NNB) to progress beyond this hold point will be based upon evidence that the NSSS components have been manufactured to adequate quality and that this is supported by appropriate records. This evidence is being gathered partly through regulatory interventions at the various manufacturing sites.

A series of quality events were identified at St Marcel and Creusot Forge during 2019 that have resulted in a range of quality improvement measures.

Purpose of Intervention

The focus of this intervention was to review the immediate and short term measures that have been put in place to address the shortfalls and the integrated quality improvement plan.  While the intervention considered Framatome’s activities, ultimately it assessed NNB’s arrangements for controlling and overseeing the manufacturing of HPC components.

Interventions Carried Out by ONR

The intervention comprised of a visit to Framatome St Marcel over two days in which Framatome presented information and evidence related to the management of quality and, in particular, the measures being developed to improve quality.

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

During recent months NNB has made demands to Framatome to improve the quality of parts being manufactured for HPC. From the evidence gathered during the intervention I believe that Framatome St Marcel had responded positively to NNB’s demands and it is expected that the measures when fully implemented should lead to sustainable quality improvements.

The integrated quality improvement plan has only recently been launched and, while some actions have been completed, many are due to be completed towards the middle of, or at the end of, 2020. In the meantime, manufacture of HPC parts continues and consequently, regulatory focus is on the short term and immediate quality improvement measures.

I recognise that the failure modes and effects analysis (FMEA) activities that have been introduced since around June 2019, should, if correctly implemented, reduce the risk of quality events occurring in the future. However, in my opinion there were aspects of Framatome’s analysis of quality events that may limit the effectiveness and timeliness of any immediate improvements. For example, I note that a substantial number of welding events occurred over 2018/19 before Framatome implemented remedial action in November 2019. Furthermore the remedial action used welding check-sheets that, in my opinion, were prone to human error and could be improved.

Conclusion of Intervention

Based upon the overall evidence gathered during the intervention, I have rated NNB’s arrangements as GREEN. There were, however, aspects of the quality improvements and NNB’s response to these that I believe require improvement. ONR is currently monitoring NNB’s oversight of the Framatome quality improvement measures through a regulatory issue. NNB’s oversight arrangements over the NSSS supply chain will be explored in more detail during a forthcoming regulatory intervention.