- Site: Dungeness B
- IR number: 21-160
- Date: March 2022
- LC numbers: 10, 23, 24. 27, 28, 34
Executive summary
Purpose of Intervention
The purpose of this intervention was to undertake a planned system based inspection (SBI) at EDF Nuclear Generation Limited’s (NGL’s) Dungeness B (DNB) power station, in line with the 2021/22 DNB integrated intervention strategy (IIS).
Interventions Carried Out by ONR
A team of ONR specialist Chemistry and Chemical Engineering inspectors and the nominated site inspector performed an SBI to confirm the implementation of safety claims made for the carbon dioxide (CO2) storage, distribution, processing and blowdown systems. The SBI examined the adequacy of the implementation of the licensee’s arrangements for the following licence conditions (LCs): LC 10 Training, LC 23 Operating Rules, LC 24 Operating Instructions, LC 27 Safety Mechanisms, LC 28 Examination, inspection, maintenance, and testing and LC 34 Leakage and escape of radioactive material and radioactive waste.
The objective of the inspection was to form an overall judgement on whether the systems adequately fulfil the requirements of the safety case.
During this station visit, the site inspector also undertook routine engagement meetings with the Technical and Safety Support Manager and the Station Director.
The intervention was performed in line with ONR's guidance requirements (as described in our technical inspection guides) in the areas inspected.
Explanation of Judgement if Safety System Not Judged to be Adequate
On the basis of the evidence sampled during this inspection, we judged that, overall, the CO2 storage and distribution system and the CO2 processing and blowdown systems fulfil the requirements of the safety case and are adequate.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
Based on the areas sampled, we considered that DNB has implemented suitable arrangements to ensure that the systems are maintained and operated in accordance with the safety case and the station’s arrangements.
In summary, the outcome of the SBI was as follows:
- We were satisfied that the licensee had implemented adequate arrangements for suitable training for staff responsible for the operation and maintenance of the systems. We judged a rating of Green to be appropriate against LC 10.
- We were satisfied that the safety case conditions and limits have been correctly identified and where necessary have been incorporated into technical specifications. We judged a rating of Green to be appropriate against LC 23.
- We were satisfied that operating instructions were in place to support plant operations and consider that, based on the evidence sampled during this intervention, an inspection rating of Green is appropriate for LC 24.
- We were content that suitable and sufficient safety mechanisms, devices and circuits were connected and in working order, with identified operating limits and conditions to meet the requirements of the safety case. An inspection rating of Green was therefore appropriate for LC 27.
- Based on our sample of maintenance documentation, we observed that the systems were being maintained appropriately and on this basis have assigned a rating of Green against LC 28.
- We were content that appropriate measures were in place to detect and control leakage and escape of radioactive material from the CO2 system, based on the information sampled. We judged a rating of Green to be appropriate against LC 34.
Conclusion of Intervention
On the basis of the evidence examined during the SBI, we considered that the CO2 storage and distribution system and the CO2 processing and blowdown systems meet the requirements of the safety case.
There are no findings from this inspection that could significantly undermine nuclear safety and no change to the planned interventions and inspections of DNB is required.