Office for Nuclear Regulation

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Dungeness B - Planned intervention

Executive summary

Purpose of intervention

This is a planned inspection at EDF Energy Nuclear Generation Ltd's (NGL's) Dungeness B (DNB) power station, undertaken as part of the planned intervention strategy for the Civil Nuclear Reactor Programme (CNRP) of the Office for Nuclear Regulation (ONR).

Interventions Carried Out by ONR

We (the incoming and outgoing DNB site inspectors and a mechanical inspector) completed a planned System Based Inspection (SBI) of "shutdown systems - control rod system", safety system grouping SBI28. The objectives of an SBI are to confirm that the relevant safety systems and structures are able to meet the safety functional requirements defined in the safety case and to test implementation of the Licence Condition (LC) arrangements for: LCs 10 (training); 23 (operating rules); 24 (operating instructions); 27 (safety mechanisms, devices and circuits); 28 (examination, inspection, maintenance and testing); 34 (leakage and escape of radioactive material and radioactive waste).

We (the incoming and outgoing DNB site inspectors) had a routine meeting with NGL's internal regulator [Independent Nuclear Assurance (INA)] and reviewed the ONR issues database with NGL.

We (the incoming and outgoing DNB site inspectors) undertook information gathering. This included site inspector handover meetings and follow up of several incidents on the site by the outgoing site inspector only.

Explanation of Judgement if Safety System Not Judged to be Adequate

Based on the information sampled we made an overall judgement that the relevant safety systems and structures are able to meet the safety function requirements defined in the safety case and are adequate.

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

In relation to the LC10 element of the SBI, we judge that staff training records and profiles are in accordance with the post training profile requirements. Therefore, we judged the LC10 element of this inspection to be adequate, warranting an associated Integrated Intervention Strategy (IIS) rating of 3 - Adequate.

In relation to the LC23 element of the SBI, based on the evidence sampled during this inspection, the implementation of the technical specifications, commentaries, and schedules were judged to be generally consistent with the claims presented within the Dungeness B Station Living Safety Case Documents (LSDs) and System Based Views (SBVs). The licensee demonstrated adequate knowledge and understanding in the areas of the safety case and how they relate to the operating rules and instructions in place for the Shutdown Systems and Control Rod Systems.

We did however identify several areas for improvement during the walkdown inspection in terms of hazard withstand capability associated with leak management. An action was therefore placed to provide the programme dates for restoring hazard withstand capability for the Shutdown and Control Rod Systems. An issue has been raised to address this and is recorded on the ONR issues database, this will be tracked and managed by the Dungeness Site Inspector. Therefore, we judged the LC24 element of this inspection to be below standard, warranting an associated Integrated Intervention Strategy (IIS) rating of 4 - Below Standard.

In relation to the LC24 element of the SBI, based on the evidence sampled during this inspection and discussion with operations and maintenance personnel, the operating and maintenance instructions were judged to be adequate with no areas for concern identified. Therefore, we judged the LC24 element of this inspection to be adequate, warranting an associated Integrated Intervention Strategy (IIS) rating of 3 - Adequate.

In relation to the LC27 element of the SBI, compliance with respect to LC27 was largely by means of adequate arrangements being implemented through LC23 and LC28. We were satisfied that safety mechanisms were being appropriately addressed even though they were not specifically identified within the maintenance schedule, no areas for concern were identified. Therefore, we judged the LC27 element of this inspection to be adequate, warranting an associated Integrated Intervention Strategy (IIS) rating of 3 - Adequate.

In relation to the LC28 element of the SBI, the licensee demonstrated that there are adequate processes, procedures and records in place for the examination, inspection, maintenance and testing of nuclear safety significant areas of plant. Several samples were taken and suitable records were produced for each sample. In terms of the System Heath Indication Programme (SHIP) we judge the performance to be adequate, no areas for concern were identified. Therefore, we judged the LC28 element of this inspection to be adequate, warranting an associated Integrated Intervention Strategy (IIS) rating of 3 - Adequate.

In relation to the LC34 element of the SBI, the licensee demonstrated that containment is being appropriately maintained and no leaks have been identified on the Dungeness B LC34 schedule, no areas for concern were identified. Therefore, we judged the LC34 element of this inspection to be adequate, warranting an associated Integrated Intervention Strategy (IIS) rating of 3 - Adequate.

In relation to the other activities undertaken in this visit, no key findings arose.

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 obtained during this intervention, no matters have been identified that are likely to have a significant impact on nuclear safety on the station at this time. Therefore, no additional regulatory action arising from this visit is considered necessary at this time other than the management of the ONR issue raised, which will be managed by the Dungeness B Site Inspector.