Office for Nuclear Regulation

Hinkley Point C – Inspection ID: 52287

Executive summary

Date(s) of inspection:

  • April 2023

Aim of inspection

NNB Generation Company (HPC) Ltd (NNB GenCo) has contracted the manufacture of the Hinkley Point C (HPC) primary circuit to Framatome, which in turn has sub-contracted the production of some of the large shell forgings for the reactor pressure vessel (RPV), the steam generators and pressurisers to Japan Steel Works (JSW). In 2022, evidence emerged of irregularities in the manufacturing records for the forgings made by JSW and an initial “phase 1” investigation, performed by a nuclear licensee task force, suggested that no nuclear parts had been affected. A separate investigation, commissioned by JSW itself, undertaken by a team of Japanese lawyers referred to as the special investigation committee (SIC), reported that irregularities were more widespread, and that nuclear equipment was affected. Consequently, the licensee’s task force, is undertaking further “phase 2” investigations into the events.

The inspection reviewed the activities undertaken by the task force set up to investigate the report of inappropriate conduct at JSW to inform ONR’s judgement as to whether NNB GenCo’s assessment of high integrity primary circuit forgings is appropriate.

The inspection took place at NNB GenCo’s offices and reviewed the scope and findings from the task force investigation into the inappropriate conduct, informed by the SIC Report. It included an assessment of the task force activities and findings prior to the issue of the SIC Report and the ongoing activities following its issue.

Subject(s) of inspection

  • LC19 – Construction or installation of new plant – Rating Green

Key findings, inspector’s opinions and reasons for judgement made

Regarding HPC, NNB GenCo and Framatome are assessing the potential impact of the inappropriate conduct on the ability to demonstrate the integrity of the RPV, steam generators and pressurisers and considering what further activities should be undertaken to obtain confidence in the integrity of those components.

I consider that the task force and NNB GenCo understand the significance of the SIC’s findings and that the phase 2 investigation is intended to be an exhaustive review of the available records.

From the evidence presented at the inspection, I judge that the task force’s phase 2 investigations are properly targeted, recognising the constraints for accessing the JSW servers, and that NNB GenCo has an appropriate level of involvement and oversight at this stage. The JSW corporate organisation has put in place a quality management organisation (QMO), that reports independently to its head office, which (amongst other tasks) is overseeing the retrieval and transfer of records to ensure the reliability of the information seen by the task force. It is therefore considered important that the task force assesses the ability of the QMO to provide rigorous oversight of the process.

The task force acknowledges that its phase 2 investigation may not arrive at a definitive conclusion regarding the full extent of the irregularities for HPC forgings and as a consequence, NNB GenCo is considering what additional measures may be needed to support the high integrity claims on some of the primary circuit components.


The inspection concluded that the ongoing task force investigation is appropriately targeted and that NNB GenCo has sufficient oversight at this stage. On this basis I have rated the inspection as green against Licence Condition 19 (construction or installation of new plant).

ONR will continue regular engagements with NNB GenCo on this matter and will follow up on several areas identified through this inspection.

My judgement relates only to the conduct of the task force phase 2 investigation and to NNB GenCo’s involvement and oversight of it.