Office for Nuclear Regulation

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Intervention on the adequacy of welding, non-destructive testing and surveillance (WN1)

Executive summary

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.

Welding requires high levels of control to ensure quality requirements are met and hence ONR seeks to ensure the licensee has developed appropriate arrangements to ensure welded items are manufactured to the appropriate quality. Therefore, it was deemed proportionate to conduct a planned intervention to gain confidence that the licensee has adequate arrangements in place for compliance with LC 19, in relation to welding, non-destructive testing (NDT) and surveillance of components manufactured at Framatome St Marcel facility intended for the Hinkley Point C (HPC) project.

Interventions Carried Out by ONR

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.”

ONR carried out the following LC19  ‘Construction or installation of new plant’ inspection:

Part 1 (Bristol) covering the following topics relating to welding and NDT:

Part 2 (St Marcel) covering the following topics relating to welding and NDT:

The aim of the intervention was to gain confidence that the licensee has adequate arrangements in place for compliance with LC 19, in relation to welding, NDT and surveillance of components manufactured at Framatome St Marcel facility intended for the HPC project.

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

The key findings are that:

Conclusion of Intervention

The licensee appeared to have adequate arrangements in place for surveillance, consumable storage, welder training and non-destructive testing of weld cladding within its supply chain at the Framatome St Marcel facility.

An action has been placed on the licensee to address the findings regarding root cause analysis and interpass temperature. A Level 4 Regulatory Issue has been raised to capture the action.

An inspection rating of GREEN is appropriate at this stage for LC19 (Construction or installation of new plant) as only minor shortfalls were identified.