Office for Nuclear Regulation

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Hunterston B Power Station – Reactor 3 Statutory Outage 2015 - LC28 Compliance Inspection in support of Structural Integrity

Executive summary

Purpose of intervention

This report records the findings of an intervention visit to the Hunterston B Nuclear Power Station during the 2015 Reactor 3 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 NGL to determine the adequacy of the work being undertaken on Reactor 3 in complying with the requirements of Licence Condition 28. 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 halfway through the periodic shutdown. The status of the inspections highlighted satisfactory progress on the reactor external inspection programme, with 241 out of 384 inspections completed at the time of this inspection, and the reactor internal inspections were not yet started.

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 categorising of the results, and was satisfied with what I found. 

I sampled the operation of the licensee’s Outage Assessment Panel (OAP) during my visit, by observing OAP meeting 4. 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.

I undertook a plant walk down during my visit, escorted by the OAP Chair and Flow Assisted Corrosion (FAC) co-ordinator. 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 reviewed the reactor internal inspection programme, at the time of my visit none of the inspections had started as the vessel entry complex was not complete.

I discussed progress on inspection, maintenance and testing activities associated with the cooling water systems. The work programme was said to be progressing according to plan and I witnessed some of this programme of work during my plant walk down.

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

I discussed progress on the steam and feed pipework hanger survey. The pre-outage hot hanger survey was complete and reported; the cold survey was in process and was due to be audited by NGL contract partner EASL after our visit. Final results will be reported through the OAP. Following the Return to Service (RTS), a post-outage hot survey will be performed.

Conclusion of Intervention

I judge that, at the time of my visit, Hunterston B nuclear power station personnel were conducting their inspections in line with the pre-outage intentions documentation and associated inspection specifications.  The inspections conducted so far have not raised any nuclear safety significant issues of concern and the licensee appears to be adequately managing any defects or anomalies identified.

At the time of my visit, and from my sample inspections, I found nothing that in my opinion would prevent Reactor 3 returning to service following completion of the 2015 periodic shutdown.  I will use the minutes from the remaining OAPs to monitor for any 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 Hunterston B Reactor 3 following its 2015 periodic shutdown.

Based on my intervention to date, I conclude that the licensee has performed the work to an adequate standard. I propose that an IIS rating of 3 (adequate) is appropriate.