Office for Nuclear Regulation

Sizewell C – Inspection ID: 52797

Executive summary

Date(s) of inspection:

June 2023

Aim of inspection

Japan Steel Works (JSW) is a manufacturer of high-integrity components for the nuclear industry.

JSW delivers to customers such as Framatome who in turn supply nuclear licensees after further assembly.

In the UK, Sizewell C Ltd (SZC Ltd) is purchasing high-integrity items from Framatome and so certain components are being manufactured by JSW.

In May 2022, JSW substantiated a whistle-blower’s complaint that “inappropriate conduct in quality inspections” existed at their Muroran factory.

The Muroran factory manufactures components for power generation, nuclear power-related components, castings and forgings for general industries and other cast and forged steel components.

JSW set up a Special Investigation Committee (SIC) to inquire into the circumstances and it found misconduct at the Muroran factory, which it described in its report. There were nine types of misconduct found in relation to nuclear power-related components.

JSW committed to make improvements to its arrangements. JSW’s President promised reforms to the organisation’s structure and culture to regain the trust in its products that had been lost.

JSW supplies its nuclear products to many countries and so several national regulators have common interest in checking JSW’s reformed arrangements. So, there were inspectors from Finland, Japan, France, Czech Republic, USA and UK on the nine-strong team.

The inspection was held over three days at Muroran and focused on JSW’s arrangements to secure the nuclear safety of components, particularly any improvements designed to make misconduct less likely, and on Framatome’s associated oversight arrangements.

Within this overall focus, and based on a reading of the SIC Report, the inspection team identified detailed topics to inspect at the Muroran factory.

For these topics, the team interviewed personnel (including senior managers, managers and workers), examined documents (such as procedures), sampled records, observed conditions in the factory and followed how data from tests was secured.

Subject(s) of inspection

  • Health & Safety at Work Act, Section 6 (General duties of manufacturers) – Rating: GREEN

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

The inspection team found that JSW has made some positive changes to its organisation and systems for quality management which were being felt, and enacted, by employees. For example, improvements in training for staff and creation of a headquarters-based Quality Management Office (QMO). The QMO oversees the work of Quality Assurance Groups within each of JSW’s factories and reports directly to the JSW President. This is a different reporting line to the Quality Assurance Groups in each factory. Further, JSW had adjusted the authority of the engineering department and established a production control department for delivery and costs. There were more reports raised by employees under the system for non-conformances. There were posters explaining the ten traits for a healthy nuclear safety culture from the World Association of Nuclear Operators (WANO).

The inspection team found that Framatome was engaging positively with JSW and providing them with coaching, with workshops and lessons-learned sessions. Framatome were conducting more unannounced inspections in the factory, without JSW accompanying them.

The inspection team recommend that JSW consider improvements in certain areas. For example, employees should see more information related to JSW’s progress on reforms, by way of better visualisation of information in the workplace. JSW’s investment in digitisation of activities, such as measurement and testing, should continue, taking care to secure the integrity of electronic data during the transition from current paper-based systems. JSW should strengthen its understanding of raw data and secure its integrity from its actual origin in (for example) certain electronic measuring devices like spectrometers. And JSW should set up a system to identify, track and close-out recommendations for improvement that they receive from other parties, such as Framatome, SZC Ltd and auditors.


The inspection team concluded, from the evidence, that JSW has in place, and is improving, arrangements to secure the nuclear safety of components and these arrangements will make misconduct of the kind described in the SIC Report less likely. So, overall, JSW is working on regaining the trust lost in its products, in line with the commitment made by its President.

The inspection team also concluded from the evidence that Framatome has put in place, and is resourcing, satisfactory arrangements to oversee manufacturing quality of products at JSW.

ONR will follow up on JSW’s response to the inspection team’s recommendations through future contacts with Framatome and SZC Ltd.