Office for Nuclear Regulation

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Hunterston B - Reactor Unit 4 Statutory Outage

Executive summary

Purpose of Intervention

This intervention report relates to an inspection I undertook at Hunterston B (HNB) power station during the 2017 statutory outage of reactor Unit 4. It was conducted as part of a series of planned ONR interventions related to the outage.

The aim of this intervention was to establish whether EDF Energy, Nuclear Generation Ltd's (the Licensee) statutory outage work programme for HNB, was being conducted in compliance with the Ionising Radiations Regulations 1999. Relevant ONR guidance was used during the inspection, in particular, Nuclear Safety Technical Inspection Guide, NS-INSP-GD-054 Revision 4, The Ionising Radiations Regulations 1999.

My conclusions on these matters informed the development of my overall opinion of the Licensee's readiness to bring reactor Unit 4 back to power in due course.

Interventions Carried Out by ONR

The following matters were addressed during the intervention:

Explanation of Judgement if Safety System Not Judged to be Adequate

No safety system inspection was undertaken, hence this is not applicable.

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

My inspection did not reveal any significant nuclear safety issues that required action by the Licensee or follow-up by ONR. My discussions with the Head of Radiological Protection at the Station and his team indicated their strong commitment to effective radiological protection practice and a good level of compliance with the IRR99 was evident during plant inspections; Accordingly, I have assigned an IIS rating of Green.

The Station and the Radiological Protection Fleet Manager agreed that NGL's process for undertaking and pre-outage planning ALARP reviews and reports could be significantly improved. The RP Fleet Manager undertook to commence revision of the company process in order to ensure meaningful, effective, and consistent outage ALARP reviews and reports take place at all stations.

The Station has for some time recognised that:-

An ALARP Committee Working Group has been assigned the task of reducing the number of PCEs.

Conclusion of Intervention

From a radiological protection standpoint, I was content with the Licensee's conduct of its statutory outage work programme and with its level of compliance with the IRR99.

On the basis of my inspection of the IRR99 aspects of the Unit 4 outage, I would support a Consent under licence condition 30 to allow Unit 4 at the Station to return to normal operating service.