Office for Nuclear Regulation

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Sizewell B - System Based Inspection - SBI 11

Executive summary

Purpose of intervention

The purpose of this intervention was to undertake a system based inspection and a site licence compliance inspection at EdF Nuclear Generation Ltd’s Sizewell B power station in line with the inspection programme contained in the Sizewell B Integrated Intervention Strategy for 2015/16.

Interventions Carried Out by ONR

The ONR Site Inspector, Mechanical Engineering Inspector and Fault Studies Inspector, referred to as “we” within this report, conducted a System Based Inspection of System 11 (Residual Heat Removal System and Reactor Building Spray System) at Sizewell B nuclear power station.  Through examination of this system, we performed compliance inspections against the following licence conditions of the Nuclear Site Licence i.e. LC 10: Training; LC23: Operating Rules; LC24: Operating Instructions; LC27: Safety Mechanisms, Devices and Circuits; LC28: Examination, Inspection, Maintenance and Testing (EIM&T) and LC34: Leakage and Escape of Radioactive Material.  The inspection was based on sampling the implementation of the arrangements in place at the station against each licence condition.

The ONR Site Inspector, Leadership and Management for Safety Inspector and Outage Project Inspector also undertook a routine LC 36: Organisational capability, inspection as part of this intervention.

Explanation of Judgement if Safety System Not Judged to be Adequate

From the inspection we judged that overall the Residual Heat Removal System (RHRS) and Reactor Building Spray System (RBSS) met the requirements of the safety case and are adequate.

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

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

After considering all the evidence examined during the sample inspections undertaken against LCs 10, 23, 24, 27, 28 and 34 we considered that the Residual Heat Removal System and Reactor Building Spray System both met the requirements of the safety case.

From the information gathered and evidence obtained during this intervention there are no matters that could significantly undermine nuclear safety and no change is necessary to the planned interventions and inspections at Sizewell B.  An ONR issue has been raised to monitor and track resolution of the PSR2 observation relating to organisational capability.