Office for Nuclear Regulation

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EDF Energy – Nuclear Generation Ltd – Hunterston B Planned Intervention

Executive summary

Purpose of intervention

The purpose of this intervention was to undertake inspections and information exchange meetings at Hunterston B [HNB] power station in line with the planned inspection programme contained in the HNB Integrated Intervention Strategy [IIS]. 

Interventions Carried Out by ONR

As part of this intervention, I undertook a Licence Condition 4 compliance inspection relating to restrictions on nuclear matter on site. I sampled the station licence compliance arrangements and their implementation relating to the receipt of nuclear fuel onto Hunterston B and the storage of new and irradiated fuel on the licensed site. During the intervention I sampled the Station’s compliance against Technical Specification limits and conditions derived from the Hunterston B safety case for storage of irradiated fuel in the buffer store. I examined records relating to the receipt, processing and storage of fuel on Hunterston B via the Station’s proprietary material accountancy system.

I examined the station’s arrangements for compliance with Licence Condition 27 associated with safety mechanisms, devices and circuits.

I undertook information exchange meetings with the Station Director; Independent Nuclear Assurance and the station’s Western Link project manager. 

Explanation of Judgement if Safety System Not Judged to be Adequate

No safety case informed system based inspection was undertaken during this intervention.

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

I examined the station’s high-level arrangements for compliance against Licence Condition 4 and confirmed clear alignment to the company arrangements. The arrangements for management of nuclear fuel and organisational responsibilities are auditable and cascade clearly from the company arrangements. I verified that these documents adequately cross-reference against other licence condition compliance arrangements that underpin Fuel Route activities including LC17 (Management Systems), LC25 (Operational Records), LC12 (Duly authorised and other suitably qualified and experienced persons), and LC23 (Operating Rules).

The station Fuel Route Group Head presented a cogent description of the Fuel Route process and the safety envelope for ensuring continued adequate cooling of decay tubes. I sampled the station’s visible safety case for storage of irradiated fuel elements in the Supplementary Buffer Store [SBS].  I examined limits and conditions of operation relating to CO2 pressure and verified alignment between the underlying dropped fuel safety case; visible safety case and the associated operating rules.  I undertook a plant inspection of the SBS valve box through which decay tube pressures are managed.  Overall based upon my sample the standards of configuration control were judged to be adequate; however I advised the station to consider a more judicious use of padlocking arrangements on key system valves to differentiate normal plant from safety significant components. I sampled plant maintenance schedule records and confirmed that the examination, inspection, maintenance and testing requirements had been met for the plant items sampled.

I judge that the LC4 element of this inspection is adequate and as a result I have scored it as 3 (adequate) through the IIS.

I undertook a high-level inspection of the station’s arrangements for compliance with Licence Condition 27. A detailed inspection was not possible at this stage in light of ongoing dialogue between ONR and EDF NGL at a corporate level on increasing the transparency with which NGL is compliant with LC27. I sought and received sufficient assurance from the Nuclear Safety Group Head that the station is demonstrably compliant with LC27 in an implicit manner, by virtue of safety mechanism ‘availability’ requirements enshrined within Technical Specifications and the ‘good working order’ requirement embodied within the plant maintenance schedule [MITS]. I was assured that the station has an adequate understanding of Licence Condition 27 and how the station ensures its compliance.

I judge that the LC27 element of this inspection is adequate and as a result I have scored it as 3 (adequate) through the IIS.

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

Conclusion of Intervention

I judged that Hunterston B to be demonstrably compliant with its arrangements under Licence Condition 4 and Licence Condition 27, justifying IIS Ratings of 3 – Adequate for both.

There are no findings from this inspection that could significantly undermine nuclear safety and no change to the planned interventions and inspections of Hunterston B.