Office for Nuclear Regulation

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System Based Inspection

Executive summary

Purpose of intervention

The purpose of this intervention was to undertake Licence Condition (LC) compliance inspections at EDF Energy Nuclear Generation Limited's (NGL) Hunterston B power station in line with the planned inspection programme contained in the Hunterston B Intervention Plan. The compliance inspections were carried out by the Nominated Site Inspector, specialist mechanical engineering inspector and a Project Inspector.

Interventions carried out by ONR

As part of this intervention, we carried out a safety case based system inspection of the Auxiliary Cooling Systems, focusing on the Reactor Auxiliary Cooling Water [RACW] and Diverse Cooling Systems. Through examination of these systems we performed compliance inspections against Licence Conditions LC 10: Training; LC23: Operating rules; LC24: Operating instructions; LC27: Safety mechanisms, devices and circuits; LC28: Examination, inspection, maintenance and testing. The inspections were based on sampling the implementation of the arrangements in place against each licence condition.

Explanation of judgement if safety system not judged to be adequate

The safety system was judged to be adequate following this inspection.

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

From an LC10 perspective, from the evidence sampled during this inspection, we considered that the operational and maintenance requirements for training and qualification of staff in the selected system have been adequately implemented, warranting an associated IIS rating of 3 (Adequate).

From an LC23 perspective, from the evidence sampled during this inspection we considered the safety case and operating rules for the mechanical systems selected to be both adequate, in terms of content, and adequately implemented, warranting an associated IIS rating of 3 (Adequate).

From an LC24 perspective, from the evidence sampled during this inspection we considered the operating instructions for the mechanical systems selected to be both adequate, in terms of content, and adequately implemented, warranting an associated IIS rating of 3 (Adequate).

From an LC28 perspective, from the evidence sampled during this inspection we considered that the Auxiliary Cooling systems sampled are being appropriately maintained in compliance with the licensee's arrangements. During the plant inspection, we considered that the overall condition of the plant was adequate and through sampling confirmed the maintenance regimes were being adequately implemented, warranting an associated IIS rating of 3 (Adequate Standard).

Compliance with respect to LC27 was judged largely by means of adequate arrangements being implemented through LC28 and demonstrable plant availability, warranting an associated IIS rating of 3 (Adequate).

Other information exchange interactions took place during the inspection week relating to wider interventions and statutory obligations of ONR under the Health & Safety at Work Act [section 28].

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

Conclusion of intervention

After considering all the evidence examined during each of the sample inspections undertaken against LCs 10, 23, 24, 27 and 28, we considered that the Auxiliary Cooling Systems met the requirements of the safety case.

No actions or issues were raised during the inspection.

There are no findings from this inspection that could significantly undermine nuclear safety.