- Site: Sizewell B
- IR number: 21-002
- Date: April 2021
- LC numbers: 28
Executive summary
Purpose of Intervention
This report records the findings of an intervention visit to the Sizewell B Nuclear Power Station during the 2021 periodic shutdown. The intervention was undertaken to confirm the adequacy of the work conducted by the licensee, EDF Energy Nuclear Generation Limited (NGL), to comply with the requirements of Licence Condition 28, examination, inspection, maintenance and testing.
Interventions Carried Out by ONR
ONR inspectors carried out inspections against the requirements of Licence Condition 28: examination, inspection, maintenance and testing, to inform the ONR decision relating to the issue of a licence instrument for consent for return to service of Sizewell B following its periodic shutdown (Licence Condition 30). The activities of the intervention were items judged important to nuclear safety.
The structural integrity inspection scope sampled the licensee’s arrangements for Examination, Inspection, Maintenance and Testing (EIMT) tasks, its implementations of those and whether it met regulatory expectations concerning LC28 – EIMT.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
I visited site approximately two weeks into the planned periodic shutdown. I sampled the inspection work that had been undertaken as part of the inspection programme and was generally satisfied with what I found.
I am content that NGL were managing the thermal sleeve failure event appropriately but also understood that further time was required for a suitable recovery strategy to be developed.
I discussed progress on examinations and inspections undertaken by the Pressure Systems Safety Regulations (PSSR) Competent Person (CP) during the periodic shutdown. I judge that, during my visit, the PSSR examinations were being managed effectively by the Licensee and the CP and no significant issues had been found.
I am content that NGL are managing the corrosion programme effectively and are actively seeking to incorporate the lessons learned into normal station operations.
I undertook a plant walk down during my visit, escorted by an NGL engineers. NGL staff were able to provide satisfactory explanations of both the operation of the systems and the inspection/maintenance of the systems planned or already performed during the periodic shutdown. Based upon the evidence provided I judge that the Licensee has carried out the CST repairs efficiently and effectively to the appropriate standard. No significant safety issues were identified with any if the systems witnessed during the walkdown.
I suggested that further coaching was required to close the minor gaps identified with procedural adherence for the surge nozzle inspections. I also suggested that the Licensee consider whether further hold points are required in the inspection procedure to give some level of oversight for such a significant inspection of a critical component.
Conclusion of Intervention
I judge that, at the time of my visit to the Sizewell B nuclear power station, personnel were conducting their inspections in line with the pre-outage intentions documentation and associated inspection specifications. I judge that the Licensee was adequately managing any defects or anomalies identified.
I will maintain an oversight for any emerging issues, from the inspections that have yet to be completed, and the thermal sleeve event recovery via the Structural Integrity Panel meeting minutes and regular update meetings and report on this in my structural integrity assessment report on the return to service of Sizewell B following its 2019 periodic shutdown.
Based on my intervention to date, I conclude that the licensee has performed the work to an adequate standard. I consider that, in accordance with ONR guidance on the application of inspection ratings, a green rating is appropriate.