Executive summary
Date(s) of inspection:
December 2025
Aim of inspection
Licence Condition (LC) compliance inspections are an essential element of ONR's intervention strategy intended to establish whether NNB Generation Company Ltd and it’s supporting services (hereafter referred to as the licensee), have adequate arrangements in place, and are adequately implementing these arrangements for Hinkley Point C (HPC).
Group ADF (Ateliers de Fos) is a pressure vessel manufacturer and Tier 1 supplier of nuclear safety significant components for HPC. ONR carried out intervention IR-53643 at HPC (February 2025) and at ADF (March 2025) targeting licensee oversight of manufacturing and installation of ADF tanks and vessels. The intervention was rated amber, and a Level 3 Regulatory Issue was raised (RI-12525) due to a number of significant shortfalls identified relating to the structural integrity of ADF tanks and vessels.
It was deemed proportionate to carry out a follow-up inspection (IR-54194) to gain assurance that the shortfalls identified in RI-12525 had been adequately addressed and the necessary improvements had been implemented. This consisted of a 1-day compliance inspection at HPC in accordance with LC12 and LC19.
LC12 requires that: ‘The licensee shall make and implement adequate arrangements to ensure that only suitably qualified and experienced persons perform any duties which may affect the safety of operations on the site or any other duties assigned by or under these conditions or any arrangements required under these conditions.’
LC19 requires that: ‘Where the licensee proposes to construct or install any new plant which may affect safety the licensee shall make and implement adequate arrangements to control the construction or installation.’
The licensee provided an agenda prior to the intervention (WIRED: ONRW-932509302-22741).
Subject(s) of inspection
- LC12 - Duly authorised and other suitably qualified and experienced persons - Rating: Green
- LC19 - Construction or installation of new plant - Rating: Green
Key findings, inspector's opinions and reasons for judgement made
During my inspection, I sampled the nuclear safety consequences of ADF stainless steel tank and vessel failure, arrangements for suitably qualified and experienced personnel (SQEP) relating to welding and non-destructive testing (NDT), ADF surveillance arrangements, welding consumable control, corrosion management, radiography arrangements and licensee oversight.
The licensee provided an overview of the confirmed CFSI event at Groupe ADF, which is associated with hydrotest water quality issues, and was formally notified to ONR via INF-5689. I noted that the investigation is still ongoing. This will be followed-up by the ONR Installation Assurance Lead in the Quality workstream.
I also carried out a site walkdown to visually inspect a sample of ADF stainless steel tank and vessels. Based on the sample visual inspection I carried out, the tanks and vessels appear to be in good condition with no visible signs of corrosion. There were various ADF tanks and vessels which were fully wrapped under care and maintenance arrangements, or inaccessible for close inspection, and therefore I was not able to see the weld and base material of these tanks and vessels. However, I was able to see that they were adequately wrapped which gave me confidence in the care and maintenance arrangements.
Conclusion
At the time of my intervention, and from the information I have sampled in relation to ADF, I judge the arrangements for LC12 - Suitably Qualified and Experienced Persons, and LC19 - Construction or installation of new plant to be adequate from a structural integrity and installation assurance perspective. I have sampled the implementation of these arrangements and found the majority to be adequate. One sample relating to SQEP did not fully meet my expectations. However, I am content there are no technical concerns based on a subsequent review carried out by the licensee’s welding SQEP and I note the licensee has enhanced it’s SQEP review expectations going forwards. I have also recommended that the ONR Organisational Capability Specialist Inspector further samples implementation of LC12 arrangements, across various disciplines.
With regards to Level 3 Regulatory Issue RI-12525, the licensee has successfully closed seven actions and made improvements to nuclear safety. Two actions remain open with credible plans in place for closure.
On balance, in accordance with ONR guidance on the application of inspection ratings, I judge a green rating is appropriate for this inspection.