Office for Nuclear Regulation

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Sizewell B - SBI 04 Chemical and Volume Control System

Executive summary

Purpose of intervention

The main purpose of this intervention was to undertake a system based inspection (SBI) at EdF Energy Nuclear Generation Ltd’s (EdF NGL) Sizewell B (SZB) power station.  The system inspected was system 04 – Chemical and Volume Control System - CVCS (System BP) and Emergency Charging System – ECS (System BG). The inspection was conducted in line with the inspection programme contained in the SZB integrated intervention strategy (IIS) for 2015/16. 

Interventions Carried Out by ONR

The ONR Site Inspector and two specialist inspectors, referred to as “we” within this report, conducted a SBI of System 04 (CVCS and ECS) at SZB 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 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.

During this intervention the Site Inspector also undertook a number of other meetings with the Licensee to review regulatory issues and reported events.   The Site Inspector also attended the Sizewell Stakeholders Group meeting during this visit.

Explanation of Judgement if Safety System Not Judged to be Adequate

From the inspection we judged that overall the CVCS and ECS system 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 inspection, we considered that the Chemical and Volume Control System and Emergency Charging System met the requirements of the safety case.

From the information gathered and evidence obtained during this intervention a minor area for improvement was raised with the licensee, which the licensee accepted and will be tracked and closed as a part of the ONR issue management.  However, no matters were been identified that are likely to have significant impact on nuclear safety on the station at this time. Therefore we consider that no additional regulatory action arising from this visit is necessary currently, and the interventions for SZB power station, set out in the integrated intervention strategy, should continue to be implemented as planned.