Office for Nuclear Regulation

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Torness - Reactor 1 Periodic shutdown - LC28 inspection - Structural Integrity

Executive summary

Purpose of Intervention

This report records the findings of an intervention visit to Torness Nuclear Power Station during the 2017 Reactor 1 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

I undertook on-site meetings and plant inspections with relevant staff from the licensee to determine the adequacy of the work being undertaken. I concentrated my intervention on items I judged important to nuclear safety, focussed on structural integrity.

I sampled aspects of the inspection programme undertaken during the periodic shutdown on the steam and feed systems and other safety related systems external to the reactor pressure vessel. I also sampled aspects of the inspection programme undertaken on the metallic components internal to the reactor pressure vessel.

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

I visited site approximately half way through the periodic shutdown, according to the licensee’s programme. The status of the inspections highlighted satisfactory progress on the reactor external inspection programme, with 241 out of 322 inspections completed at the time of my visit.

I sampled the inspection work that had been undertaken as part of the reactor external inspection programme, looking at both the inspection work itself and the categorisation of the results, and was satisfied with findings. Steel pipework weld and Flow Accelerated Corrosion (FAC) inspections were progressing to programme with no significant issues identified.

I sampled the operation of the licensee's outage assessment panel (OAP) during my visit. The OAP meets to review the inspection work undertaken during the periodic shutdown and sentences the inspection findings. I was satisfied that the OAP was following due process and that the inspection items raised were challenged appropriately.

I undertook a plant walk down during my visit, escorted by the OAP Chair and the relevant plant responsible persons. The licensee was 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 sampled digital images and video footage from the inspections of the reactor internal components. I judged that due process was being followed satisfactorily. No significant issues that could affect the planned work were reported and no significant issues have been reported with the internal inspections to date.

I discussed progress on inspection, maintenance and testing activities associated with the cooling water systems. The inspections were progressing according to programme with no significant issues identified.

I discussed progress on examinations and inspections undertaken during the periodic shutdown, as required by the Pressure Systems Safety Regulations (PSSR). The PSSR competent person was working together with the licensee to determine the extent of degradation on some of the feed system vessels.

I discussed progress on steam and feed pipework and the associated hanger survey. A large package of work was being completed on the replacement of flexible hoses with balanced bellows on the steam relief valve escape pipework. The hanger survey work was in process and on target for completion, with only seven high priority remedial actions required at this outage.

Conclusion of Intervention

I judge that, at the time of my visit to Torness nuclear power station, personnel were conducting their inspections of Reactor 1 in line with the pre-outage intentions documentation and associated inspection specifications. The personnel who we spoke to during our intervention were well prepared for our discussions and knowledgeable of their specific work programmes.

Based on the information that I have sampled during my visit to site, I have not identified any further nuclear safety significant issues of concern. I am satisfied that the licensee is adequately managing any defects or anomalies identified. I will use the minutes from the remaining OAPs to monitor for any additional emerging issues from the inspections that have yet to be completed and report on this in my structural integrity assessment report on the return to service of Torness Reactor 1 following its 2017 periodic shutdown.

I judge that, from a structural integrity perspective, the licensee has performed the examination, inspection, maintenance and testing work to an adequate standard against the requirements of LC28. At the time of my visit, the remediation work identified as part of these routine inspections is being progressed satisfactorily and will be subject to further inspections in accordance with the licensee’s internal arrangements before a request for consent to return to service is made. I consider that a GREEN rating is appropriate for this inspection, warranting no formal regulatory action required.