Executive summary
Date(s) of inspection:
- March 2023
Aim of inspection
I undertook an inspection at Sizewell B during Refuelling Outage 18 (RO18).The aim of the inspection was to sample evidence to support (or otherwise) the recommendation to the project inspector that the plant may be safely started up and safely operated until the next periodic shutdown in support of Licence Condition 30 (periodic shutdown), from a civil engineering perspective (NS-INSP-GD-030 Revision 6).This was undertaken in accordance with General Inspection Guide (ONR-INSP-GD-064) by carrying out targeted compliance inspection and sampling of the primary containment structure against Licence Conditions (LCs) 23 (operating rules) and 28 (examination, inspection, maintenance and testing) compliance inspections.
The intervention also enabled ONR to:
- Discuss progress of regulatory issue RI-11079;
- Gather intelligence in respect of wider asset management strategies and implementation.
Subject(s) of inspection
- LC 23 – Operating rules – Rating: GREEN
- LC 28 – Examination, inspection, maintenance and testing – Rating: GREEN
Key findings, inspector’s opinions and reasons for judgement made
The primary containment structure in conjunction with the reactor building liner and containment isolation provisions form the primary containment boundary. The primary containment minimises any radiological release to the environment during both normal and faulted conditions. ONR inspected EDF Energy Nuclear Generation Ltd.’s (EDF NGL) compliance with its arrangements made under the following LCs to form a judgement on their adequacy from the perspective of maintaining the primary containment boundary:
LC23 – Operating Rules
I sampled the safety case ‘identified reference’ and related technical specification (Tech. Spec.) for primary containment leak rate testing. Penetrations are a potential source of leakage by-passing the primary containment. I was able to trace operational limits and conditions to relevant safety cases, and into more detailed surveillance requirements. Based on my sample, I judge that EDF NGL is adequately implementing its arrangements with respect to operating rules relevant to civil engineering aspects of the primary containment boundary. I award a Green rating – No Formal Action, on the basis that I identified no significant shortfalls, in accordance with ONR-INSP-GD-064.
LC28 – Examination, Inspection, Maintenance and Testing
I sampled evidence relating to the examination, inspection, maintenance and testing requirements. Based on my sample, I judge EDF NGL to be adequately implementing their maintenance and surveillance routines in respect of the civil engineering aspects of the primary containment. In respect of RI-11079, I am satisfied that suitable work is planned during and soon after the outage to address the actions placed upon EDF NGL. I award a Green rating – No Formal Action, on the basis that I identified no significant shortfalls, in accordance with ONR-INSP-GD-064.
Conclusion
Based on my inspection and sampling in relation to the civil engineering aspects of the primary containment boundary, I found EDF NGL’s existing arrangements and their implementation in respect of LC 23 and LC 28 to be adequate. I therefore award a GREEN rating in accordance with ONR’s General Inspection Guide (ONR-INSP-GD-064) and note I have found no reason to object to the proposed reactor restart from a civil engineering perspective during my inspection.