Office for Nuclear Regulation

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Sizewell B Refuelling Outage (RO) 13 - Second Outage Visit, Mechanical Inspection and LC 26 inspection

Executive summary

Purpose of intervention

This inspection was undertaken as part of ONR’s strategy to support the regulatory decision for the EDF Energy Nuclear Generation Limited (NGL) Sizewell B application for consent to restart under licence condition 30(3). The mechanical inspection was carried out as a Licence Condition (LC) compliance inspection of LC28 (Examination, inspection, maintenance and testing) and is one of several specialist inspections undertaken as part of the Sizewell B Refuelling Outage 13. The intervention also included plant inspections and meetings carried out as part of the Project Inspector role for the outage, included here for completeness.  During this visit the nominated site inspector also carried out a planned Licence Condition (LC) compliance inspection of LC26 (Control and supervision of operations) and gathered information on a recent incident regarding a missed surveillance routine.

Interventions Carried Out by ONR

The interventions carried out as part of the mechanical inspection against Licence Condition 28 (Examination, inspection, maintenance and testing), and covered the following areas:

Whilst on site in the capacity of RO13 project Inspector, the opportunity was taken for information gathering in the following areas:

The nominated site inspector undertook a planned compliance inspection of control and supervision of operations (LC26) and gathered information on a recent incident regarding a missed surveillance routine during this site visit.

Explanation of Judgement if Safety System Not Judged to be Adequate

Not applicable

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

I am satisfied that suitable testing is carried out to ensure operation of the control rods are in line with the safety function. The results of the control rod drop tests continue to be in line with the safety case and Technical Specification requirements and show no sign of deterioration. The trialling of new methods of enhancing effectiveness of the control rods in terms of fuel bowing measurements are in line with my expectations for continuous improvement and best available technology. From an Licence Condition 28 perspective,  I judge an IIS rating of 3 (Adequate) to be appropriate.

I am satisfied with the arrangements for the control of foreign material exclusion, however I support the finding of the Rapid Trending Review that improvements to the standards seen in specific areas of could be readily achieved and could in my judgement, deliver significant benefit. Overall I consider the practices adequate and therefore judge an IIS rating of 3 to be appropriate.

During the visit the following information gathering activity was undertaken:

The nominated site inspector undertook a plant visit, observed the setting to work of maintenance teams and held various discussions on at points of work relating to arrangements for the control and supervision of operations as required under licence condition 26. The site inspector was satisfied that the implementation of the arrangements for control and supervision, inspected during this intervention, are adequate and judged an IIS rating of 3 to be appropriate. 

Conclusion of Intervention

From a mechanical perspective, and in line with the requirements of LC28, my inspection found no safety significant issues. I therefore have no objection to the proposed activity (returning of Sizewell B Reactor to power).

From the evidence sampled during the inspection the arrangements for LC26 - control and supervision of operations are judged to be adequate.  The nominated site inspector will follow up the Licensee’s response to the incident relating to missed surveillance routine during normal routine business.