Office for Nuclear Regulation

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Torness System Based Inspection - SBI 07 - No Break Supplies System

Executive summary

Purpose of Intervention

This was a planned inspection of EDF Energy Nuclear Generation Ltd.'s (NGL's) Torness power station, undertaken as part of the planned intervention strategy for the Operating Facilities Division (OFD) of the Office for Nuclear Regulation (ONR).

The work was carried out in-line with the planned inspection programme contained in the Torness Integrated Intervention Strategy (IIS).

Interventions Carried Out by ONR

During this intervention, the following key activities were undertaken:

Explanation of Judgement if Safety System Not Judged to be Adequate

From the inspection, I judged that the no break supplies system met the requirements of the safety case and was adequate.

Key Findings, Inspector's Opinions and Reasons for Judgements Made

From the System Based Inspection on the no break supplies system I concluded that:

For the information gathering intervention on the VFC thyristor event, I was content, from an electrical engineering perspective, that the station was continuing to work towards fully identifying and understanding the causes of this event and were developing and implementing appropriate remediation strategies.

The intervention was performed in line with ONR’s guidance requirements (as described in our technical inspection guides) in the areas inspected.

Conclusion of Intervention

From the evidence sampled during this SBI-07 inspection against LCs 10, 23, 24 and 28, I consider that the no break supplies system met the requirements of the safety case.

For the information gathering intervention, I was content with the explanations, discussions and advice given and was content that there was no need for any regulatory action at this point.

There are no findings from this inspection that could significantly undermine nuclear safety. At present, no additional regulatory action is needed over and above the planned interventions at Torness Power Station as set out in the Integrated Intervention Strategy, which will continue as planned.