- Site: Dungeness B
- IR number: 21-050
- Date: July 2021
- LC numbers: 10, 23, 24, 27, 28, 34
Executive summary
Purpose of Intervention
The purpose of this intervention was to carry out a System Based Inspection (SBI) of the sea defences, flood protection and drainage system and planned compliance inspections for licence condition 6 (Documents, records, authorities and certificates), LC25 (Operational records) at EDF Energy Nuclear Generation Limited’s (EDF NGL) Dungeness B (DNB) power station.
The intervention was planned in accordance with ONR’s Integrated Intervention Strategy (IIS) for DNB 2021/22.
Interventions Carried Out by ONR
The SBI inspection was undertaken by a multi-disciplinary team of ONR inspectors, including the DNB site inspector, Civil Engineering, Fault Studies / Probabilistic Safety Analysis, External and Internal Hazards specialist inspectors. The aim of the inspection was to confirm the adequacy of implementation of the safety case against the following licence conditions:
- LC 10 Training
- LC 23 Operating Rules
- LC 24 Operating Instructions
- LC 27 Safety Mechanisms, Devices and Circuits
- LC 28 Examination, Inspection, Maintenance and Testing (EIMT)
- LC34 Leakage and escape of radioactive material and radioactive waste
The nominated site inspector for Dungeness B also undertook planned compliance inspections of LC 6 and LC25 in addition, the site inspector also undertook routine engagements and intelligence gathering in the form of a plant visit to the reactor charge face, discussions with the Station Director and the Defueling Preparations Manager and follow up of a planning application proposal with the Environmental Safety Group Head.
The intervention was performed in line with ONR's guidance requirements (as described in our technical inspection guides) in the areas inspected.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
From the System Based Inspection on the FM, PU & PA, I concluded that:
- LC 10 (Training) – I examined the training records of a number of personnel involved in operations and maintenance activities associated with the flooding system. I judged that the personnel sampled were either suitably qualified and experienced or had appropriate control and supervision in place. I found that a System Engineer was not compliant against a number of training modules that are assigned to their role. I have therefore raised a regulatory issue for this minor non-compliance. I also had discussions on the arrangements in place to ensure personnel are suitability trained to mitigate the impacts of infrequent internal and external hazard events. These were considered appropriate for ensuring staff are suitably trained and experienced. I therefore assigned a rating of Green (no formal action) for LC10 compliance.
- LC23/ LC24 - (Operating Rules) and LC 24 (Operating instructions) - I sampled the flooding safety case and associated Technical Specification to determine whether the principal limits and conditions were identified and enacted into station procedures and operator surveillances. I considered the principal limits and conditions of the safety case were identified in the station’s technical specifications. For LC 24, I sampled the Safety Operating Instruction for flooding and found that limits and conditions were implemented through clear working instructions. Overall, I considered NGL provided an adequate level of assurance and evidence to demonstrate compliance against LC 23/24. As such, an inspection rating of Green (no formal action) was assigned for LC 23/24.
- LC 27 (Safety Mechanisms, Devices and Circuits) – I sampled the active safety systems serving the pond area. This included the pond water cooling system, the pond water temperature monitoring and alarm system, the pond basement sump level monitoring and alarm system and seismic monitoring equipment. Based on this and the other areas sampled during this inspection (LC23, 24 &28), I was satisfied that suitable and sufficient safety mechanisms, devices and circuits are connected and in working order to meet the requirements of the safety case. As such, an inspection rating of ‘Green’ (no formal action) was assigned for LC 27.
- LC 28 (Examination, Inspection, Maintenance and Testing) – I sampled the maintenance and testing records of various plant and equipment associated with the flooding safety case, which included the sea flood wall, sea defences, seismic and flood management, drainage systems, Cooling Water (CW) pump house and pond area. From the sampled areas under consideration I have concluded that the regimes relevant to the Examination, Inspection, Maintenance and Testing (EIMT) were adequate. As such, an inspection rating of Green (no formal action) was assigned for LC 28.
- LC34 (Leakage and Escape of Radioactive Material and Radioactive Waste) – I sampled the ponds area given it has a significant radioactive inventory. Based on my sample I found that the personnel, plant and processes provide adequate control and containment of radioactive materials and radioactive wastes so far as is reasonably practicable to prevent their leakage or escape. I also found adequate detection, notification, recording, investigation and reporting of any leakage or escape that occurs. As such, an inspection rating of Green (no formal action) was assigned for LC34.
For the compliance inspections of LC6 and 25, my sampled inspection of the station’s data store repository identified that there had been further improvements since my last inspection in September 2020. Further rationalisation of the store’s contents had been undertaken, only a few areas remain to be progressed which the station is still on track to complete. My examination of station documents, condition monitoring arrangements for the data store identified that the DNB was meeting its regulatory requirements for its LC6 and 25 arrangements, I have therefore concluded that this inspection warranted a green rating for both license conditions.
Conclusion of Intervention
From the evidence sampled during this SBI, I judged that sea defences, flood protection and drainage system adequately fulfils the requirements of the safety case and fulfils its safety functional requirements. I have judged there was a minor shortfall in compliance with LC10 and have raised a regulatory issue in order to follow the station’s progress in addressing this gap.
For the LC6 and 25 compliance inspections I concluded that the station was meeting its regulatory requirements for its LC6 and 25 arrangements, I have therefore concluded that this inspection warranted a green rating for both license conditions.
The intervention findings were shared and accepted by NGL as part of normal inspection feedback.