Office for Nuclear Regulation

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2015 Reactor Periodic Shutdown – Inspection of examination, maintenance and testing in support of steel structural integrity

Executive summary

Purpose of intervention

This report records the findings of our intervention visit to Hinkley B Nuclear Power Station during the 2015 reactor 4 Statutory 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 and their contractors to determine the adequacy of the work being undertaken on Reactor 4 in complying with the requirements of Licence Condition 28.  We concentrated on items judged important to nuclear safety.

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

The first day of our visit, was day 46 of a 74 day periodic shutdown.  The steam system inspections were progressing well with 535 inspections.  We examined the process for sanctioning inspection findings by sampling and found it to be adequate.   We sampled the inspection of components judged to be important to safety and were satisfied with what we found.  The remaining inspections will be sampled and dealt with in the return to service assessment report.  The inspections had found defects in the de-aerator; at the time of our inspection the repairs were complete.  The repair documentation will be sampled as part of the return to service assessment report.

Based on the sampled inspections, I noted no matters that I considered inadequate.  The findings of all steam system inspections are undergoing sentencing by the licensee and issues requiring advice were being referred to their outage assessment panel, according to the relevant NGL process.

At the time of our visit, the reactor internal inspections were almost complete with no major issues identified.  I sampled inspection footage obtained from the inspections of the boiler re-heater components.  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 to NGL.

The inspections required to comply with the Pressure Systems Safety Regulations were progressing and no significant issues had been identified to date. 

During the 2011 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 outage assessment panel.  I will assess the panel’s response as part of my return to work assessment.

I reviewed the inspections and rectification work undertaken as part of the hanger survey and restraint movement programme.  The pre-outage hot survey was complete and the cold survey and remedial work was progressing.  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 inspections were nearly complete with two components still to be inspected.  I will review the findings of the inspections as part of my return to service assessment report.

Conclusion of intervention

I judge that Hinkley Point B nuclear power station personnel were conducting their inspections in line with the pre-periodic shutdown intentions documentation and were dealing adequately with any defects or anomalies found.

From my sample inspections, I found nothing that, in my opinion, would prevent Reactor 4 returning to service on completion of the 2015 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.