Office for Nuclear Regulation

Reactor 3 Statutory Outage 2015 – Mechanical Inspection

Executive summary

Purpose of intervention

The purpose of this intervention was to carry out licence compliance inspections at the EDF Energy Nuclear Generation Limited’s (NGL) Hunterson B power station in line with the planned inspection programme contained in the Hunterston B Integrated Intervention Strategy (IIS) for 2015/16. 

Interventions Carried Out by ONR

I carried out inspections against the requirements of Licence Condition (LC) 28, Examination, Inspection, Maintenance and Testing to inform the ONR decision whether to issue a licence instrument granting consent for the return to service of Hunterston B Reactor 3 following its 2015 statutory outage.  The activities examined were selected due to their nuclear safety significance and agreed in advance of the visit with the Hunterston B station and site inspector.

The inspection included:

I also followed up NGL’s progress in addressing the following matters of interest to ONR mechanical engineering discipline:

Significant Adverse Condition Investigation 896866 – Gas circulator protection system trip due to an oil system shutdown

ONR Issue 1262 relating to an inconsistency in configuration of the safety relief valve filters fitted to NGL’s fuel charge machines.

The intervention was performed in line with ONR’s guidance requirements (as described in our technical inspection guides) in the areas inspected.

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

Based on my sampling, I am satisfied from a mechanical engineering perspective that during the Hunterston B Reactor 3 2015 statutory outage:

Also, suitable and sufficient records are been kept and monitored to identify problems both reactively and proactively.

I am satisfied that NGL is implementing suitable measures to prevent the gas circulator lubrication systems being inadvertently taken out of service whilst the gas circulators are running.

I am satisfied that Hunterston B power station has an appropriate strategy in place to address obsolescence of the charge (fuelling) machine pressure relief valve filters.

Conclusion of Intervention

This report presents the findings of the mechanical engineering intervention of the LC28 examination inspection maintenance and testing arrangements in place to support the 2015 Hunterston B Reactor 3 periodic shutdown.

Based on my sampling undertaken as part of this intervention, I am satisfied that the LC 28 arrangements in place are adequate and have been adequately implemented. I have therefore given this LC28 inspection an IIS rating of 3 – adequate.  This intervention will form part of the mechanical engineering assessment report for the Hunterston B Reactor 3 2015 statutory outage.