Office for Nuclear Regulation

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Dungeness B Planned Intervention

Executive summary

Purpose of intervention

This was a planned systems based inspection at EDF Energy Nuclear Generation Ltd's (NGL's) Dungeness B (DNB) power station, undertaken as part of the planned Integrated Intervention Strategy (IIS) for the Operating Reactors Programme of the Office for Nuclear Regulation (ONR).

The intervention included a system based inspection (SBI) of Control & Instrumentation to demonstrate compliance with the safety cases for the selected systems. This inspection was performed by the ONR nominated site inspector and two [C&I] specialist inspectors.

Interventions Carried Out by ONR

The key inspections during the Control & Instrumentation SBI were for licence compliance covering the following licence conditions (LC);

The SBI inspection looked at the following C&I related systems:

No additional SBI licence condition inspections were undertaken during this intervention.

During this intervention, the following key activities were also undertaken:

Explanation of Judgement if Safety System Not Judged to be Adequate

Not applicable

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

An inspection of R21 C&I systems was carried out as part of the operating reactors programme 2016/17 to confirm that the C&I systems meet the requirements of the safety case.

The inspection has found that the sampled systems inspected important to nuclear safety have been operated and maintained satisfactorily. The inspection of the systems covered during this intervention has found that the operation, calibration, testing and maintenance applied were adequate although inconsistencies were identified with the maintenance instructions and records.

For LC 10, we inspected the training of staff involved in operating or maintaining C&I systems. We judged that the training was appropriate. We found that all had their training marked as up to date. We considered that the Licensee's arrangements for suitable training for staff with responsibilities for the maintenance to be adequate and assigned an IIS rating of green (no formal action) against LC10.

For LC 23, we inspected compliance with the technical specifications relevant to the C&I systems. We were satisfied that the operating rules in place to support plant operations were adequately managed and implemented. Since we did not identify any areas where the Licensee was not compliant, we judged that compliance with LC 23 was adequate and hence assigned an IIS rating of green (no formal actions).

For LC 24, we reviewed the content of two operating instructions for C&I systems and witnessed a walkthrough of one of them. We identified inconsistencies with the implementation of the operating instructions in place to support plant operations. We agreed actions to improve this and gave an amber IIS rating (seeking improvement) against LC24.

LC27 - No safety mechanisms, devices or circuits were identified within the systems included in the SBI. Whilst the systems inspected did have safety related functionality their safety significance was low and there were alternative arrangements to maintain the necessary monitoring functionality. We therefore judged that LC 27 was not applicable to these systems.

For LC 28, we inspected 5 items within the maintenance schedule to ensure that they had been completed within the maintenance interval and 3 further items where we inspected the detailed records of completion of the maintenance. Whilst we found that all of the maintenance had been completed within the required intervals we identified shortfalls with the records and inconsistencies in the instructions for some of them. We agreed actions to improve this and gave an amber IIS rating (seeking improvements) to LC28.

We were satisfied that the only system associated with the control of radioactive material (BCD) was adequately managed. We gave a green IIS rating (no formal action) against LC 34.

Finally, the system based inspection requires an assessment of the plant condition, which was based on discussions with the Licensee on its own assessment and a walk-down of the plant. For the majority of the systems covered by the SBI, we found the plant condition to be acceptable.

We have raised seven actions as a result of this inspection, none of which prevents continued operation at Dungeness B power station. These have been recorded in an ONR issue to ensure that the actions are suitably discharged.

In relation to the other activities undertaken in this intervention, 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

After considering all the evidence examined during the sample inspection undertaken against LCs 10, 23, 24, 27 and 28, we considered that the requirements of the safety case have been adequately implemented at Dungeness B power station.

From the evidence obtained during this intervention, no matters have been identified that are likely to have a significant impact on nuclear safety or protection of the public in the event of an emergency on the Station at this time. Therefore, no additional regulatory action arising from this visit is considered necessary at this time.