Executive summary
Date(s) of inspection:
February 2025
Aim of inspection
Licence Condition (LC) compliance inspections are an essential element of ONR's intervention strategy on any nuclear site and consist of a series of inspections, each of which is intended to establish whether NNB Generation Company (HPC) Ltd and it’s supporting services (hereafter referred to as the licensee), have adequate arrangements in place, and are adequately implementing these arrangements, for compliance with a specific LC.
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.'
Operating Experience (OPEX) from tanks and vessels manufactured by ADF identified quality issues with welding and radiography (Ref. 101069731 - WIRED: ONRW-932509302-16859). The ADF tanks and vessels are important to nuclear safety, therefore, the aim of this inspection was to gain confidence in the structural integrity of tanks and vessels manufactured by ADF and their subsequent installation at HPC. The intervention consisted of 2 parts. Part 1 consisted of a one day inspection at HPC. Part 2 consisted of a one day inspection at ADF manufacturing facility in France (factory FAB 2 La Feuillane in Fos-sur-Mer). The intervention was supported by ONR Supply Chain and Installation Assurance specialist inspectors. The licensee provided an agenda prior to the intervention (WIRED: ONRW-932509302-19006).
Subject(s) of inspection
- LC12 - Duly authorised and other suitably qualified and experienced persons - Rating: Amber
- LC19 - Construction or installation of new plant - Rating: Amber
Key findings, inspector's opinions and reasons for judgement made
This inspection was undertaken in response to Operating Experience (OPEX) from tanks and vessels manufactured by ADF where quality issues with welding and radiography were identified.
The ONR inspection team consisted of a Structural Integrity Specialist Inspector, Supply Chain Specialist Inspector and the HPC Installation Assurance Lead. For the purpose of this intervention report, the opinions of the inspection team shall be referred to as “I”.
During my inspection, I sampled the licensee’s implementation of the corrective action plan for quality shortfalls identified at ADF, nuclear safety functions including design and NDT, Welding Procedure Specification and Procedure Qualification Record acceptance, walkdown/visual inspection of ADF tanks and vessels at HPC including implementation of care and maintenance, summary of findings from the ADF ISO Quality audit, ADF internal surveillance arrangements, control of welding consumables, observation of welding activities and control of parent materials during manufacture, review of radiographs, licensee oversight and surveillance of ADF during manufacture, and Nuclear Safety Culture at ADF applicable to LC12 and LC19.
I was satisfied that the licensee had completed the corrective action plan and carried out follow-up checks to form a judgement on the implementation effectiveness.
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.
I noted that ADF had initiated internal (independent) quality audits and were addressing the observations to make the necessary improvements.
ADF acknowledged that improvement in their nuclear safety culture is required, and I am satisfied that ADF is progressing towards a positive nuclear safety culture.
The following shortfalls were identified throughout the intervention:
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Finding A: The licensee/RD were not able to substantiate the consequences of nozzle weld failure (LC12 and LC19).
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Finding B: The RD have not been able to demonstrate that ADF welding procedures have been reviewed and accepted by suitably qualified and experienced persons on behalf of the licensee (LC12 and LC19).
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Finding C: Welding inspector personnel qualification requirements have not been specified (LC12 and LC19).
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Finding D: Surveillance checks for welding inspection were not specified (LC19).
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Finding E: Lack of welding consumable control at ADF (LC19).
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Finding F: Corrosion management risks identified with manufacturing procedures (LC19).
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Finding G: Radiography shortfalls identified for weld repairs (LC19).
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Finding H: Delivery timeframe for radiographs to be sent to HPC was not specified (LC19).
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Finding I: Adequacy of licensee oversight and surveillance in relation to (LC12 and LC19).
The aggregation of findings identified throughout this intervention highlight significant shortfalls with LC12 and LC19 which require improvement. This will be monitored through Level 3 Regulatory Issue RI-12525.
At the time of my intervention, and from the information I have sampled, I consider that, in accordance with ONR guidance on the application of inspection ratings, a AMBER rating is appropriate for this inspection.
Conclusion
At the time of my intervention, and from the information I have sampled, I judge there to be significant shortfalls against LC12 - Suitably Qualified and Experienced Persons, and LC19 - Construction or installation of new plant. Therefore, in accordance with ONR guidance on the application of inspection ratings, an AMBER rating is appropriate for this inspection.