Dungeness B - Planned Intervention and ARoS
- Site: Dungeness B
- IR number: 17-017
- Date: April 2017
- LC numbers: 10, 23, 24, 27, 28, 34
Purpose of Intervention
This was a planned inspection of EDF Energy Nuclear Generation Ltd's (NGL's) Dungeness B power station, undertaken as part of the planned intervention strategy for the Operating Facilities Division of the Office for Nuclear Regulation (ONR).
The work was carried out in-line with the planned inspection programme contained in the Dungeness B Integrated Intervention Strategy (IIS).
Interventions Carried Out by ONR
During this intervention, the following key activities were undertaken:
- System based inspection (SBI) of the instrument air and turbine overspeed systems.
- Update on reported events and ONR regulatory issues.
- Attendance at the Annual Review of Safety meeting.
Explanation of Judgement if Safety System Not Judged to be Adequate
From our inspection, we judged that the instrument air and turbine overspeed systems fulfil the safety functional requirements of the safety case.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
From the system based inspection on the instrument air and turbine overspeed systems, we concluded that:
- LC 10 (Training) - We examined the training records of a number of personnel involved in operations and maintenance activities associated with the instrument air and turbine overspeed systems. We judged that the personnel undertaking these operations and maintenance activities were suitably qualified and experienced. We therefore assigned a rating of Green (no formal action) for LC 10 compliance. Notwithstanding this we identified a minor discrepancy with the training records for a newly appointed system engineer. Remediation actions were agreed with EDF NGL and a regulatory issue has been raised to track completion.
- LC 23 (Operating Rules) - The technical specifications adequately specified the limits and conditions of operation (LCO) reflecting those specified in the safety case. In addition, surveillance records and compliance check sheets demonstrated that the technical specifications were adhered to during operations. We therefore assigned a rating of Green (no formal action) for LC 23.
- LC 24 (Operating Instructions) - We examined a number of station operating instructions (SOIs) and plant item operating instructions (PIOI). We judged these documents to be of an adequate standard and therefore assigned a rating of Green (no formal action) for LC 24.
- LC 27 (Safety Mechanisms, Devices and Circuits) - The turbine overspeed protection system and non-return valves on the instrument air system were considered as safety related systems. We examined and confirmed that they were adequately maintained and tested on a regular basis. We judged that a rating of Green (no formal action) was appropriate for LC 27.
- LC 28 (Examination, Inspection, Maintenance and Testing) - We examined a number of maintenance schedule items and work order cards. We confirmed that the periodicity of maintenance activities was appropriate and the maintenance instructions appropriately completed. We judged that the instrument air and turbine overspeed systems plant and equipment was being adequately maintained. We therefore assigned an IIS rating of Green (no formal action) to this LC. Notwithstanding this we noted a minor inconsistency in the maintenance schedule relating to functional testing of SRVs (safety relief valves) and inspections of the instrument air compressor air receivers. Remediation actions were agreed with EDF NGL and a regulatory issue has been raised to track completion.
- LC 34 (Leakage and Escape of Radioactive Material and Radioactive Waste) - The instrument air and turbine overspeed systems do not contain radioactive material and therefore LC34 was not considered as part of this inspection.
I reviewed the licensee's progress against a regulatory issue and evaluated the licensee's response to incidents occurring on the site. No significant safety concerns were raised and I confirmed that the station was taking appropriate action.
We attended the Annual Review of Safety Meeting, including a plant walk-down. We are pleased to observe that investment is being made at the station and we continue to seek timely delivery of further nuclear safety improvements. The meeting was considered to be effective and encouraged open discussion and challenge on a number of safety areas.
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 the evidence presented by NGL, we concluded that the arrangements and their implementation, associated with the instrument air and turbine overspeed systems met the requirements of the safety case. An IIS rating of Green (no formal action) is considered to be appropriate. Two level 4 regulatory issues were raised in order to monitor agreed remedial actions against two minor compliance shortfalls relating to training and maintenance schedule.
There are no findings from the interventions that could significantly undermine nuclear safety.