Office for Nuclear Regulation

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Mid Outage Inspection

Executive summary

Purpose of intervention

This report covers an inspection at EDF Energy Nuclear Generation Limited’s (NGL) Sizewell B site. The inspection considered the power electrical activities being undertaken as part of the major outage and updates to previous inspections.

Interventions Carried Out by ONR

As part of this intervention, ONR carried out compliance inspections against Licence Condition (LC) 28, ‘Examination, inspection, maintenance and testing’ and LC22, ‘Modification or experiment on existing plant with respect to the change out of Generator Transformer 1.

Explanation of Judgement if Safety System Not Judged to be Adequate

Not applicable.

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

In respect of the outage activities, I am satisfied that the majority of electrical activities are progressing to schedule with no significant issues found during the outage. Furthermore, I received reassurance that all planned activities would be completed before return to service, with the exception of the deferral of maintenance of one 3.3 kV and one 11 kV switchboard.  Justification for this deferral has been requested from the licensee.

A plant walkdown identified minor deficiencies which the licensee agreed to rectify within defined timescales and these are noted in this report.  

A sample review of outage electrical maintenance records highlighted no concerns with the test results and the records had been completed, as expected.

Conclusion of Intervention

From the evidence gathered during this intervention, I am satisfied that the outage activities are being managed in an appropriate manner and that actions raised during the intervention are being appropriately managed.

The overall outcome from the inspection is that no electrical issues have been identified from this work that should affect the return to service, on completion of the planned and emergent work