Office for Nuclear Regulation

Hunterston B - Outage inspection

Executive summary

Purpose of Intervention

Site licence condition 30 requires EDF Energy Nuclear Generation Ltd to periodically shutdown each reactor at its nuclear power stations.  This is to undertake the examination, inspection, maintenance and testing of systems, structures and components important to safety in accordance with the requirements of Site License Condition 28 (LC28).

This inspection is undertaken to provide regulatory confidence in the mechanical engineering aspects of the licensee’s arrangements during the planned safety related activities through this shutdown.  The activities being undertaken are in accordance with the requirements of the maintenance schedule, statutory inspections, modifications and other important work.  The purpose was also to inform the ONR decision relating to the issuing of a Licence Instrument for Consent for return to service, under LC30, following the 2019 periodic outage of Hunterston B.

Interventions Carried Out by ONR

The inspection covered by this intervention record was undertaken in support of ONR’s 2018/19 statutory shutdown inspection programme.  My inspection sampled and examined three planned shutdown activities:

The inspection covered EDF Energy Nuclear Generation Ltd’s arrangements for compliance with LC28, examination, inspection, maintenance and testing.  The findings of this inspection will contribute to ONR’s regulatory decision to grant consent to the return of Hunterston reactor 3 to normal operating service in accordance with Licence Condition 30 (LC30) (Periodic shutdown).

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

We examined written instructions used by operators to undertake examination, inspection, maintenance and testing.  The sample taken confirmed that activities are carried out in accordance with written instructions, with a specified periodicity.

Conclusion of Intervention

From the sample inspected, I judged that, for mechanical engineering activities undertaken at Hunterston B Reactor 3, 2019 periodic outage, compliance against LC28 met the required standard.  I have therefore given this inspection an Integrated Intervention Strategy rating of Green.

From a mechanical engineering standpoint, I was content with the way in which the licensee was conducting its statutory shutdown work programme.  Accordingly, I am of the opinion there is no observed or emerging evidence that should prevent the licensee bringing the Hunterston B Reactor 3 back to power in due course.

At the time of writing this record, from a Mechanical Engineering perspective, I recommend that ONR grants Consent to the restart of Hunterston B Reactor 3 under LC30, following the 2019 Statutory Outage.