Executive summary
Date(s) of inspection
- May 2026
Aim of inspection
The inspection is to provide ONR with confidence in NNB GenCo (HPC) Ltd’s governance arrangements – technical and corporate – for commissioning.
The inspection will include a review of the governance framework in place and any planned evolution, and how it interfaces with construction and operations. It will also look to understand the oversight of the Commissioning Alliance by the Commissioning Programme and how assurance is gained on its ability to deliver the required activities.
Subject(s) of inspection
- LC17 - Management systems - Rating: Green
- LC21 - Commissioning - Rating: Green
Key findings, inspector's opinions and reasons for judgement made
Overall, ONR found that governance arrangements are established and generally effective. However, as commissioning activities increase, further clarity, simplification, and integration with the wider HPC governance framework will be required to ensure robust decision-making, clear escalation routes, and effective oversight.
Implementation of the arrangements will need to be further demonstrated through ongoing and future inspection activities.
Conclusion
The inspection found that NNB has responded to previous ONR findings and strengthened its governance arrangements.
Governance and technical decision-making processes are established and broadly effective. However, these arrangements are evolving and will require further development to ensure they remain effective as commissioning activities scale. They should taking consideration of:
- maintaining clarity in governance structures
- ensuring clear delegation and escalation routes
- simplifying processes to support an increase in commissioning activities
The evidence showed that learning is being captured and used and the shift required in safety culture is being set out and communicated. Their effectiveness will require continued monitoring.
Overall, the evidence supports a Green rating, with minor opportunities for improvement.