Office for Nuclear Regulation

Sizewell B - LC28 Structural integrity inspection

Executive summary

Purpose of Intervention

This report records the findings of an intervention visit to the Sizewell B Nuclear Power Station during the 2019 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.

ONR inspectors’ intervention included but was not limited to; a plant walkdown, observation of the Structural Integrity Panel (SIP) and sampling of the personnel’s training record.

Key Findings, Inspector's Opinions and Reasons for Judgements Made

I visited site approximately one third of the way through the periodic shutdown. The status of the inspections showed satisfactory progress of the surface and volumetric inspection programmes, with 82 out of the 190 inspections completed at the time of this inspection.

I sampled the inspection work that had been undertaken as part of the surface and volumetric inspection programme, looking at both the inspection work itself and the categorising of the results, and was satisfied with what I found.

I undertook a plant walk down during my visit, escorted by an NGL inspection engineer. 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.

I discussed progress on examinations and inspections undertaken by the Pressure Systems Safety Regulations (PSSR) Competent Person (CP) during the periodic shutdown. The work was generally progressing to plan and no significant issues had been found to date.

I discussed the progress of the flow assisted corrosion (FAC) programme to date. No significant findings were reported and progress appeared to be reasonable given the timing of our inspection.

I discussed progress with the outage inspection programme co-ordinator for a number of significant systems and components and no adverse findings were reported.

I reviewed the current condition of the condensate tanks and, subject to assessment of the operability assessment provided, I am content that the corrosion identified is being appropriately addressed.

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 also judge that the Licensee is adequately managing any defects or anomalies identified.

I will use the minutes from the remaining Structural Integrity Panel meetings to monitor any emerging issues from the inspections that have yet to be completed.  I will 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.