Office for Nuclear Regulation

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Sizewell B - External Hazards Safety Case

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) Sizewell B Power Station, in line with the ONR’s Operational Facilities Division intervention strategy. The intervention was carried out by the ONR site inspector, supported by a number of specialist inspectors.  

Interventions Carried Out by ONR

We performed an intervention to evaluate implementation of the station’s external hazards safety case focusing of claims made in the event of extreme weather. The ONR site inspector also conducted an intervention to examine standards of control and supervision with maintenance and operations teams at Sizewell B. During these interventions, inspections were performed against the following Licence Conditions (LC) which are applicable provisions of the Energy Act 2013:

The ONR site inspector also carried out follow-up enquires into an incident reported by NGL via ONR’s INF1 notification system. This incident involved the discovery that some level instrumentation on the station’s refuelling water storage tank had been adversely affected during recent cold weather.

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

Explanation of Judgement if Safety System Not Judged to be Adequate

Not applicable - no system based inspections were completed during this intervention.

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

A minor compliance shortfall was noted in relation to provision of written instructions setting out the expected response to forecast low temperatures. NGL have accepted an action to resolve this finding which will be tracked to resolution via an entry on the ONR issues database.

Conclusion of Intervention

There are no findings from this inspection that could significantly undermine nuclear safety.  At present, no additional regulatory action is needed over and above the planned interventions at Sizewell B Power Station.