Executive summary
Date(s) of inspection
- July 2026
Aim of inspection
The aim of the inspection was to inspect NNB Generation Company (HPC) Ltd's (NNB GenCo) arrangements for compliance with Licence Condition (LC) 19, construction or installation of new plant and in relation to civil engineering construction assurance and with LC14, Safety documentation in relation to development of the safety case to support operation. LC19 requires that where the licensee proposes to construct or install any new plant, which may affect safety, the licensee makes and implements adequate arrangements to control the construction or installation. LC14 requires the licensee to make and implement adequate arrangements for the production and assessment of safety cases consisting of documentation to justify safety during the design, construction, manufacture, commissioning, operation and decommissioning phases of the installation.
The objective of the inspection was to obtain evidence in relation to the adequacy of NNB GenCo’s arrangements for the control of construction of structures at Hinkley Point C (HPC) in order to gain confidence that the Golden Thread of the safety case and the substantiation previously provided at the point of release to site has not been compromised during the construction phase. The particular focus of the inspection was on the development and quality of construction information to support the future safety case.
Subject(s) of inspection
- LC14 - Safety documentation - Rating: Not rated
- LC19 - Construction or installation of new plant - Rating: Not rated
Key findings, inspector's opinions and reasons for judgement made
This Licence Condition (LC) 14 (safety documentation) and 19 (construction or installation of new plant) compliance inspection was carried out on Monday 6th July and Tuesday 7th July at Hinkley Point C (HPC).
The inspection focused on the adequacy of NNB GenCo arrangements for the control of construction assurance arrangements at HPC, in order to gain confidence that sufficient substantiation has been undertaken to ensure compliance with the plant's future safety case. The inspection was carried out to gain confidence that the Golden Thread of the safety case has been maintained and not compromised during the construction phase. The inspection focused on Unit 1 structures at HPC.
The inspection initially comprised of an office based discussion on the current development of the safety case and the overall strategy for how key construction justifications documentation, such as the Design Substantiation Reports (DSR), will fit in and provide sufficient substantiation of the constructed plant.
The discussion was followed by a site walkdown, where we visited Unit 1 Raw Water Supply Building (HOR) and Unit 1 Radioactive Waste Treatment Building (HQB). During the site walkdown, we sampled areas of non-conformances and design changes that had been selected as they may impact upon the relevant safety documentation.
Overall, on the basis of the inspection and evidence sampled, I judge that LC14 and LC19 arrangements, in relation to the justification, substantiation of construction activities and alignment to the future safety case appear to be proceeding in accordance with expectations.
As the maturity of documentation available was at an early stage of development and the areas sampled were of a lesser nuclear safety significance, a decision was taken post-inspection not assign a formal rating. Regulatory oversight of construction and safety case alignment will be maintained going forward through routine engagement.
The inspection highlighted no significant regulatory issues. A small number of observations were made during the inspection and where appropriate, actions were set to address them.
Conclusion
Overall, on the basis of the evidence sampled, I judge that LC14 and LC19 arrangements in relation to the justification, substantiation of construction activities and alignment to the future safety case were in accordance with expectations.
In relation to the specific areas sampled, I judge that NNB GenCo’s development of construction substantiation documentation appears to be adequate, and will be further sampled as the future safety case is further developed.
Upon consideration of the ONR guidance in relation to inspection ratings, I determined that assigning a formal rating was not appropriate in this instance and the inspection has been marked as “not rated” due to the maturity of implementation.
Actions and minor observations have been raised for the duty holder to consider and address after the inspection, these will be monitored through routine regulatory business.