- Site: Hinkley Point C
- IR number: 22-005
- Date: May 2022
- LC numbers: 19
Purpose of Intervention
Licence Condition (LC) compliance interventions are an essential element of the Office for Nuclear Regulation’s (ONR’s) overall intervention strategy and consist of a series of interventions which are each intended to establish whether NNB Generation Company (HPC) Ltd (hereafter known as ‘the licensee’) has adequate arrangements in place 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 purpose of the intervention was to gain confidence that the licensee has adequate LC19 arrangements in place for manufacturing control over High Integrity Component (HIC) welding and non-destructive testing (NDT) for the Hinkley Point C (HPC) Main Steam Line (MSL). The MSL will be manufactured at Bilfinger premises based in Germany, following release of hold point 2.2.25 (first secondary steam system pipework weld). Once the MSL has been manufactured at Bilfinger it will be transported to HPC site for installation. This intervention has targeted the manufacturing at Bilfinger only.
The objectives of the intervention were to:
- Assess the adequacy of the licensee’s arrangements in place for HIC welding and NDT of the MSL at Bilfinger.
- Assess the adequacy of the licensee’s arrangements for hold point 2.2.25 which relates to start of HIC welding of the MSL at Bilfinger, including a summary of the evidence which the licensee intends to obtain to support release of the hold point.
- Assess the licensee’s compliance with LC19.
Interventions Carried Out by ONR
- Part 1: Observe MSL ultrasonic inspection procedure qualification trials at Jacobs Inspection Validation Centre (IVC) – 1 day site visit.
- Part 2: LC19 arrangements in place for HIC welding and NDT of the MSL at Bilfinger, and arrangements for hold point 2.2.25 – 1 day Microsoft Teams meeting.
Explanation of Judgement if Safety System Not Judged to be Adequate
N/A as this was not a safety systems inspection.
Key Findings, Inspector’s Opinions and Reasons for Judgements Made
I am content that the licensee has considered the operational experience associated with the welding and NDT of the MSL and has raised appropriate recommendations to prevent similar issues occurring for HPC.
Based on my sample, I am content that the licensee has adequate arrangements in place for MSL HIC welding at Bilfinger.
During my visit to Jacobs IVC, I observed the phased array ultrasonic testing scanning of the inspection qualification test piece. There was appropriate oversight from the IVC and licensee, and I was able to gain sufficient confidence that the MSL ultrasonic inspection procedure qualification trials are being conducted with rigour.
On the evidence reviewed, I am content that the NDT arrangements are adequate. I have requested more detailed information on the surveillance frequencies to confirm my judgement.
I am content that the licensee has adequate arrangements in place for hold point 2.2.25 from a welding perspective. I am also content the welding related evidence that the licensee is planning to obtain to support release of hold point 2.2.25 is adequate. As the summary provided was high level, I have requested the summary evidence document to support hold point 2.2.25 once available.
Conclusion of Intervention
At the time of my intervention, and from the information I have sampled, I am content that the licensee has adequate LC19 arrangements in place to control HIC welding and NDT at Bilfinger for the HPC MSL.
I consider that, in accordance with ONR guidance on the application of inspection ratings, a GREEN rating is appropriate for this inspection, with no formal action as a result of my inspection.