Office for Nuclear Regulation

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Reactor 21 and Reactor 22 return to service Readiness Inspection

Executive summary

Purpose of Intervention

The purpose of this intervention was to undertake a Licence Condition (LC) 10 and LC 28 compliance inspection at EdF Energy Nuclear Generation Limited (NGL) Dungeness B (DNB), to establish a judgement on the readiness of DNB to return Reactor 21 and Reactor 22 to service after an extended outage period. The main focus of this inspection was to sample the electrical engineering aspects of the work activities undertaken during the extended outage of Reactor (R) 21 and R 22 at DNB power station in order to confirm that electrical engineering plant and equipment important to safety are appropriate and remain fit for their intended purpose.

Interventions Carried Out by ONR

I undertook a planned inspection and assessment of implementation of the arrangements for LC 10, Training, and LC 28, Examination, Inspection, Maintenance and Testing (EIMT), at DNB Power Station.

The inspection sample targeted the planned electrical engineering work being undertaken as part of the extended R 21 and R 22 outage. This included the electrical engineering aspects of planned EIMT activities from the station’s maintenance schedule, the implementation of the required modifications and any reactive work emergent from the extended outage. This inspection contributes towards ONR’s regulatory decision to grant Consent, to the return of R 21 and R 22 at DNB to normal operating service, in accordance with LC 30 (Periodic shutdown).

Explanation of Judgement if Safety System Not Judged to be Adequate

Not applicable.

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

From the inspection of  electrical engineering aspects of the work being undertaken as part of the extended R 21 and R 22 outage I concluded:

LC 10 (Training) – I examined the training records of a number of individuals involved in the electrical engineering aspects of planned EIMT activities from the station’s maintenance schedule, the implementation of the required modifications and any reactive work emergent from the extended outage. I judged that the individuals undertaking the electrical engineering aspects of the activities were suitably qualified and experienced. No significant shortfalls were identified. I therefore assigned a rating of Green (no formal action) for LC 10 compliance.

LC 28 (Examination, Inspection, Maintenance and Testing) – I examined a limited sample of electrical engineering aspects of the planned EIMT activities from the station’s maintenance schedule, the implementation of the required modifications and any reactive work emergent from the extended outage. I confirmed that the maintenance activities were conducted periodically as determined by the maintenance schedule and that the completed work order cards were appropriately completed. I confirmed the progress of the required modifications and any reactive work emergent from the extended outage. I judged that the electrical engineering aspects of the work undertaken as part of the extended Reactor 21 and Reactor 22 outage was being adequately implemented. I therefore assigned an IIS rating of Green (no formal action) for LC 28.

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 sample inspected, it is judged that for the electrical engineering aspects of the work activities undertaken at DNB during the R 21 and R 22 extended outage, compliance against LC 10 and LC 28 met the required standard; therefore a ‘Green’ rating was given for both LCs.

Based on this targeted intervention relating to the electrical engineering aspects of the work activities, no regulatory issues were identified; therefore I have no objection to ONR granting Consent for the return to service of DNB R 21 and R 22. This is subject to: the completion of all required EIMT activities; the implementation of the required modifications; the completion of emergent electrical work; the completion of all ‘match fitness’ activities ; the provision of a view on the state of readiness of DNB to return to operational service from the EDF Energy NGL Nuclear Safety Committee (NSC) or other suitable corporate governance function and which DNB will confirm to ONR prior to restart.

In addition, DNB shall consider the following enhancements to the ‘match fitness’ activities and provide the outcome of those considerations to ONR:

Consider the use/participation of EDF Suitably Qualified and Experienced Persons (SQEP), external to DNB, as an independent on the return to service walk downs and applicable ‘match fitness ‘ activities.

Consider enhancing the maintenance standards with appropriate and applicable system engineering input.

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