Dungeness B System Based Inspection (SBI06)
- Site: Dungeness B
- IR number: 16-191
- Date: December 2016
- 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 Programme (OFP) 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 Emergency Generation System.
- Attendance at the Outage Intention Meeting.
- Quarterly update on ONR regulatory issues.
- Attendance at the annual Emergency Arrangements Review meeting.
Explanation of Judgement if Safety System Not Judged to be Adequate
From our inspection, we judged that the Emergency Generation system met the requirements of the safety case and was adequate.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
From the System Based Inspection on the Emergency Generation System we concluded that:
- LC 10 (Training) - We examined the training records of a number of personnel involved in maintenance and inspection activities associated with the Emergency Generation System. We judged that the personnel undertaking these maintenance and inspection activities were suitably qualified and experienced. We therefore assigned a rating of Green (no formal action) for LC 10 compliance.
- LC 23 (Operating Rules) - The technical specification adequately specified the limits and conditions of operation (LCO) reflecting those specified in the safety case. In addition the 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 maintenance instructions (MI). 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 Back-Up Diesel Generators and Electrical Overlay 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 instructions and work order cards. We confirmed that the periodicity of maintenance activities was appropriate and the maintenance instructions appropriately completed. We judged that the Emergency Generation System plant and equipment was being adequately maintained. We therefore assigned an IIS rating of Green (no formal action) to this inspection. Notwithstanding this we noted minor shortfalls in demonstrating compliance with safety case requirements regarding emergency diesel reliability and availability, and observed poor material condition of electrical cabinets. Remediation actions were agreed with EDF NGL and regulatory issues have been raised to track completion.
- LC 34 (Leakage and Escape of Radioactive Material and Radioactive Waste) - The Emergency Generation System does not contain radioactive material and therefore LC34 was not considered as part of this inspection.
The outage intentions meeting was well attended and the majority of ONR's queries were addressed during the meeting. It was agreed to start routine engagements with the DNB outage coordinator in February 2017 to discuss ONR's forthcoming interactions to support the permissioning work.
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
The system based inspection resulted in areas of improvement being identified in response to minor compliance shortfalls relating to plant condition and compliance with the associated safety case. Two level 4 regulatory issues were raised in order to monitor the agreed remedial action. After considering all of the evidence presented by EDF NGL we concluded that the arrangements and their implementation, associated with the Emergency Generation System met the requirements of the safety case and were adequate. An IIS rating of Green (no formal action) is considered to be appropriate for this intervention.
In relation to LC30, I judge that an IIS rating of Green (no formal action) is warranted on the basis that the station has presented a detailed scope for the forthcoming statutory outage as required by its plant maintenance schedule.