Executive summary
Date(s) of inspection:
July 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 Sizewell C Limited (SZC) 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. 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 pressuriser (PZR) is manufactured by ENSA (manufacturer of nuclear equipment based in Spain).
The PZR is a nuclear safety class 1 component which forms part of the primary circuit. It has been classified as a high integrity component (HIC) within the SZC safety case.
Therefore, the consequences of failure during operation cannot be tolerated and a highest reliability claim is made on the structural integrity of the PZR. Therefore, the aim of this inspection was to make an informed judgement on the adequacy of SZC's specification, control and oversight of pressuriser (PZR) welding and non-destructive testing (NDT) at ENSA in accordance with LC19.
Subject(s) of inspection
- LC 19 - Construction or installation of new plant - Rating: GREEN
Key findings, inspector's opinions and reasons for judgement made
The pressuriser (PZR) is manufactured by ENSA (manufacturer of nuclear equipment based in Spain). The PZR is a nuclear safety class 1 component which forms part of the primary circuit. It has been classified as a high integrity component (HIC) within the SZC safety case.
Therefore, the consequences of failure during operation cannot be tolerated and a highest reliability claim is made on the structural integrity of the PZR.
Therefore, the aim of this inspection was to make an informed judgement on the adequacy of SZC's specification, control and oversight of pressuriser (PZR) welding and NDT at ENSA in accordance with LC19.
During my inspection, I sampled SZC specified requirements for PZR welding, NCR management (internal and external), SZC control over PZR welding (review and acceptance process), welder training and qualification arrangements, arrangements for weld repair, arrangements for ultrasonic testing (UT) Inspection Qualification, Follow-up document (FUD), sample check of weld and inspection records, suitably qualified and experienced persons (SQEP) checks, oversight of PZR manufacturing, ENSA shopfloor visit and welding consumable store visit.
A summary of the findings from my inspection are as follows:
The licensee’s welding SQEP confirmed that they were involved in key decisions around replication of specified requirements for welding the SZC PZR. However, the decision was not recorded. Licensee decision making and record keeping will be explored further during a targeted cross-cutting intervention (IR-54143).I am content that the LC19 arrangements for management of non-conformance reports (NCRs) are adequate and that these are being adequately implemented. I am content that adequate LC19 arrangements are in place for PZR welder training and qualification and that these arrangements are being adequately implemented.
The licensee explained the arrangements in place if a weld repair is required.
I consider these arrangements to be adequate in accordance with LC19.I am content that adequate LC19 arrangements are in place for PZR Inspection Qualification and that these arrangements have been adequately implemented for SZC from a replication perspective. The licensee confirmed that ENSA are certified to ISO 3834 (Welding Quality Management System) which I consider to be good practice.
Based on my sample, I am content that NDT inspections performed during SZC PZR manufacturing have been carried out by SQEPs. It was noted that whilst SZC had visibility of the direction qualité industrielle (DQI) surveillance guides, and formed a view on the adequacy of these during joint surveillance activities with DQI, there didn’t appear to be a formal review of these by SZC.
I provided regulatory advice that SZC should consider how it can demonstrate that a formal review of DQI surveillance guides has been performed – Regulatory advice. I plan to follow this up during the next SZC intervention. I am content that ENSA is controlling welding consumables in accordance with its consumable control procedure.
Overall, I am content that the licensee has adequate LC19 arrangements in place for welding and NDT of the PZR at SZC, and that these arrangements are being adequately implemented.
Conclusion
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 GREEN rating is appropriate for this inspection.