Office for Nuclear Regulation

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Inspection of Examination, Inspection, Maintenance and Testing in Support of Steel Structural Integrity

Executive summary

Purpose of intervention

This report records the findings of my intervention visit to Torness Nuclear Power Station during the 2014 reactor 1 Statutory Periodic Shutdown. The intervention was undertaken to confirm the adequacy of the work conducted by the Licensee to comply with the requirements of Licence Condition 28, examination, inspection, maintenance and testing. I was accompanied on my visit by an ONR (Office for Nuclear Regulation) structural integrity principal inspector.

Interventions carried out by ONR

I undertook on-site meetings and plant inspections with relevant staff from NGL and their contractors to determine the adequacy of the work being undertaken on Reactor 1 in complying with the requirements of Licence Condition 28. I concentrated on items I judged important to Nuclear Safety.

Key findings, Inspector's opinions and reasons for judgements made

The first day of my visit, was day 38 of a 60 day periodic shutdown. The steam system inspections were progressing well with 329 inspections out of 407 complete. I inspected the process for sanctioning inspection findings by sampling inspections and found it to be adequate. I sampled the inspection of components I judged to be important to safety and was satisfied with what I found. I will sample the remaining inspections and include my judgements in my return to service assessment report. The inspections had however found defects in the reheater outlet system associated with small branch welds. Two of these components are to be replaced with new pipe sections; I will monitor this work as part of my assessment of return to service.

Based on the sampled inspections I noted no issues I considered detrimental. The findings of all steam system inspections are undergoing sentencing and issues requiring advice were referred to the outage assessment panel (OAP), as per NGL process.

At the time of my visit all the reactor internal inspections had been completed with no major issues identified during the inspections. I sampled inspection footage obtained from the inspections of the boiler economiser and decay heat tail pipes and the reheater header and reheater hangers. I was content with the quality and the content of the inspections sampled, however, I noted that the link between the inspections conducted and the safety case lacked clarity; this was communicated with NGL, and will be addressed separately to the outage.

The inspections required to comply with the Pressure Systems Safety Regulations were progressing well and no significant issues had been identified to date. I noted that there was an issue with the ownership of PSSR inspections for the gas side penetrations of the reactor pressure boundary. I have raised an action for the licensee to demonstrate satisfactory completion of the inspections not covered by the APEX and PSSR competent person.

During the 2010 outage NGL had replaces a significant amount of the reactor seawater piping system with high density polyethylene (HDPE). Inspection of the HDPE pipework highlighted no significant issues. NGL will produce a report of the reactor seawater system inspection results which will be presented to the OAP. I will assess the OAP's response as part of my return to work assessment.

I reviewed the inspections and rectification work undertaken as part of the hangers survey and restraint movement programme. The pre-outage hot survey was complete and the cold survey and remedial work was progressing well. No significant issues had been highlighted to date and I will review the findings of the completed survey as part of my return to service assessment report.

Flow assisted corrosion (FAC) inspections were nearing completion with two components still to be inspected. The results highlighted two areas which required referral to the OAP. These components were accepted for return to service without any remedial work, and were judged to require re-inspection during the 2017 outage. I will review the findings of the inspections as part of my return to service assessment report.

Conclusion of intervention

I judged that Torness nuclear power station personnel were conducting their inspections in line with the pre-periodic shutdown intentions documentations and were dealing adequately with any defects or anomalies found.

From my sample inspections, I found nothing that, in my opinion, would prevent Reactor 1 returning to service on completion of the 2014 periodic shutdown.

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

Actions

Assess the steam system inspections, reactor internal inspections, hangers survey, hot reheat pipework remedial work and the Reactor Seawater Cooling system inspections as part of the structural integrity return to service report.

I will sample the minutes of the OAP meetings held prior to Reactor 1 returning to service to ensure there are no significant emergent issues.