Office for Nuclear Regulation

NSSS1 - Tensile testing - Pressure circuit components

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 which consists of a series of interventions. Each intervention is intended to establish that the licensee has adequate arrangements in place for compliance with a licence condition. Inter alia, LC 19 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 aim of the intervention was to gain confidence that NNB Generation Company (HPC) Limited, the licensee, has adequate arrangements in place for compliance with LC 19, in relation to tensile testing of pressure circuit components and welds in order to substantiate their integrity and satisfy the regulatory expectations in ONR’s Safety Assessment Principles (SAPs). In addition, this intervention considered whether the sampled results from the tensile testing meet the requirements of the RCC-M standard and therefore the relevant fracture mechanics assessments remain demonstrably conservative.

Interventions carried out by ONR

The intervention was carried out in two parts:

Key findings, inspector’s opinions and reasons for judgments made

My findings on the main aim of the intervention, to gain confidence that the licensee has adequate arrangements in place for compliance with LC 19, in relation to the tensile testing of pressure circuit components to substantiate assurance of nuclear safety of equipment/systems at Hinkley Point C are:

Conclusion of intervention

Overall, the conclusion of the intervention is that the licensee satisfactorily demonstrated adequate arrangements for compliance with LC 19, in relation to tensile testing of pressure circuit components and welds in order to substantiate their integrity and satisfy the regulatory expectations in ONR’s SAPs. An inspection rating of Green is appropriate for LC 19 (Construction or installation of new plant).