Office for Nuclear Regulation

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Planned Inspection of Hunterston B

Executive summary

Purpose of intervention

The purpose of this intervention was to undertake Licence Condition (LC) compliance inspections at Hunterston B (HNB) power station in line with the planned inspection programme contained in the HNB Integrated Intervention Strategy (IIS). This intervention was carried out by the nominated site inspector and, in part, by a specialist Fault Studies inspector.

Interventions carried out by ONR

As part of this intervention, we carried out compliance inspections against Licence Conditions 23 - Operating Rules and Licence Condition 36 - Organisational Capability. I conducted a routine monthly meeting with HNB's Nuclear Inspection and Oversight team. We based the inspection on a sample of the arrangements in place and their implementation, assessed against published ONR Technical Inspection Guides.

Explanation of Judgement if Safety System Not Judged to be Adequate

Not Applicable - no system inspection was undertaken during this intervention.

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

We inspected NGL's corporate and HNB specific arrangements for LC23, with emphasis on the audit trail from company arrangements to Technical Specification use, surveillance and application. We also examined the NGL's arrangements for managing breaches and temporary suspensions to Technical Specifications. We judged NGL's arrangements under Licence Condition 23 to be adequate.

We sampled aspects of LC23 compliance for one system that supports the Pre-Stressed Concrete Pressure Vessel pressure relief valves (PRV), verifying concurrence between Nuclear Safety Requirements for PRV availability and associated Technical Specification requirements. We sampled maintenance instructions relating to isolation valve functional tests and for PRV return to service and judged the associated return to service arrangements to be effective. We further sampled surveillance sheets from which we were confident of compliance with associated Limits and Conditions of Operation (LCO). The specialist inspector examined the underpinning visible safety case and historical Station Safety Report to verify selected LCOs had a clearly auditable basis. We judged, based on the samples undertaken, adequate compliance with Licence Condition 23.

I undertook a compliance inspection against LC36, focussing on the nuclear site baseline. Station has demonstrably aligned its nuclear baseline to the Nuclear Industry Code of Practice published last year. Notably, baseline posts are evaluated and presented according to a consistent fleet-wide template. I examined and considered adequate Station's employee attrition rate and arrangements for managing its aging demographic - this presents continuing challenges to HNB's nuclear baseline but I secured confidence there exists is a healthy plan for recruitment at graduate and apprentice grades.

I reviewed Station's major projects and associated internal and external regulatory hold-points. This was helpful in providing familiarisation of near-term specialist resource demands. I also engaged with Station's Statutory Outage Manager to review the forthcoming Statutory Outage and key regulatory inputs.

The licence conditions were inspected against ONR's published guidance requirements (as described in our technical inspection guides).

Conclusion of intervention

We judged, based on the samples undertaken, the licensee to have adequately implemented its arrangements under Licence Condition 23. An IIS Rating of 3-'Adequate' was awarded

I judged the HNB nuclear site baseline, under Licence Condition 36,to adequately represent posts and roles essential to nuclear safety and has been produced in accordance with the recognised code of practice. An IIS Rating of 3-'Adequate' was awarded.