Office for Nuclear Regulation

Hinkley Point C – Inspection ID: 51663

Executive summary

Date(s) of inspection:

  • October 2022

Aim of inspection

The aim of the intervention was to sample the commissioning handover process developed by NNB Generation Company (HPC) Ltd (NNB GenCo) (from mechanical, electrical and heating, ventilation and air-conditioning (MEH) to commissioning but not including the handover to operations). This process has not been implemented yet, but commissioning handover exercises have taken place and it is sufficiently developed for ONR and NNB GenCo’s Internal Nuclear Regulation (INR) to sample it.

The objective of this intervention was to gain understanding and confidence on NNB GenCo’s handover arrangements for commissioning, ahead of the implementation of the process.

Subject(s) of inspection

LC21 – Commissioning – Rating – Green

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

The inspection was carried out over two days at NNB GenCo’s offices in Aztec West (Bristol).

Each day was structured around an agenda allowing discussions with key personnel and sampling of the documentation provided ahead of the meeting and during the meeting. As part of the inspection NNB GenCo provided a demonstration of the development of Commissioning Test Packages (CTPs) using the CTP tool.

Overall, the inspection team was satisfied that the commissioning handover arrangements were sufficiently developed for the current level of maturity of the project. It was noted that many of the arrangements and processes presented required further development.

The team highlighted areas for NNB GenCo to consider and develop further as the project progresses. The inspection was rated GREEN with the expectation that NNB GenCo will address the areas highlighted through normal business.


From the evidence presented, ONR concluded, the MEH to commissioning handover process is adequate for the current stage of development of the project and the inspection was rated GREEN. The inspection team noted that several handover processes needed updating and/or further development. This will be followed through the normal routes of engagement with the licensee.

The inspection team highlighted the challenges associated with the scalability of the arrangements, noting that over 1000 handovers will take place for Unit 1, and significant number of commissioning open points could be raised. In order to overcome this challenge, there is heavy reliance on the functionality (and readiness) of SWTCH as the commissioning IT tool, which is currently been developed.

The inspection team acknowledged that significant work has been undertaken developing the CTPs and the processes. Also, the electro-mechanical safety rules represent a good example of learning from the existing UK nuclear fleet.

The inspection team provided the following feedback to the licensee:

  • The licensee provided good examples of operational experience during the inspection, however those were not clearly recorded in the evidence provided.
  • An example of an End of Erection Status Report (EESR) will help to provide consistency between contractors.
  • The licensee needs to clarify if non-functional requirements will be considered in the handover process.
  • There are limitations associated with the CTP tool, such as the specification of the electrical and instrumentation and control boundaries where information is derived manually from a spreadsheet, that will require robust assurance arrangements.
  • The licensee needs to consider Control of Major Accident Hazards (COMAH) arrangements during commissioning.
  • Clarification on the overall responsibilities regarding configuration management and management of manufacturing non-conformance reports (NCRs) is an area for further consideration.
  • The governance model is an area of further interest to ONR.