Office for Nuclear Regulation

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Dungeness B - R21 Outage - Inspection of Electrical Aspects

Executive summary

Purpose of Intervention

The purpose of this intervention was to undertake a planned compliance inspection at EdF Energy Nuclear Generation Limited (NGL) Dungeness B Power Station, in line with the inspection programme contained in the Dungeness B Integrated Intervention Strategy (IIS) for 2017/18.

Interventions Carried Out by ONR

I undertook a planned inspection of implementation of the arrangements for Licence Condition (LC) 28 Examination, Inspection, Maintenance and Testing (EIMT) at Dungeness B Power Station.

The inspection sample targeted the planned electrical work being undertaken as part of the Reactor 21 2017 periodic shutdown, including the planned electrical EIMT activities from the station’s Outage Intentions Document, implementation of modifications and reactive electrical work emergent from the shutdown.

I also conducted follow-up enquires into an incident which occurred on the site involving loss of electrical supplies to a number of station transformers.

Explanation of Judgement if Safety System Not Judged to be Adequate

Not applicable.

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

Based on the discussions, explanations and the sample inspected, I was satisfied that there were no significant shortfalls identified with the implementation of the established arrangements for LC 28 in relation to the planned electrical work undertaken as part of the Reactor 21 2017 periodic shutdown. The targeted inspection undertaken confirmed that the planned EIMT and modification activities during this shutdown were appropriate and that electrical plant and equipment that was being maintained was in accordance with the established arrangements.

Overall, the outcome from the safety inspection of the shutdown related electrical activities for the R21 2017 periodic shutdown was that the implementation of the LC 28 arrangements for the electrical equipment was found to be adequate, therefore a green inspection rating was awarded.

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

In respect to my follow-up enquires, I was satisfied that the supplies to the transformers had been appropriately re-instated in a timely manner and in accordance with the established arrangements. Also, from the discussions and explanations given I was satisfied, from an electrical engineering perspective there was no significant impact to nuclear safety and no need for further regulatory action.  

Conclusion of Intervention

Based on these targeted interventions here were no issues identified from the electrical work activities which would prevent ONR granting Consent for Reactor 21 to return to service. This is subject to the completion of the planned EIMT activities, the implementation of the detailed modifications and the completion of emergent electrical work.

From the evidence gathered during these interventions, there were no matters identified that have the potential to impact significantly on nuclear safety.