Office for Nuclear Regulation

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System based Inspection SBI-12, Emergency Core Cooling Systems (ECCS) EM & BN

Executive summary

Purpose of intervention

The purpose of this intervention was to undertake Licence Condition (LC) compliance inspections at EDF Nuclear Generation Limited's (NGL's) Sizewell B Nuclear Power Station in line with the planned inspection programme contained in the Sizewell B Integrated Intervention Strategy (IIS) for 2014/15.

Interventions Carried Out by ONR

The primary intervention recorded in this report is a system based inspection of the Borated Refuelling Water Storage System (BRWSS) and High Head Safety Injection System (HHSIS). Interventions were also undertaken to consider the circumstances of the Emergency Charging (EC) pump A operability incident, to discuss the forthcoming reactor outage and matters of health and safety with the site trade union safety representatives.

Explanation of Judgement if Safety System Not Judged to be Adequate

The overall judgement is that the inspection found the BRWSS and HHSIS safety systems to be adequate.

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

I consider that the Licensee has adequately identified the root and contributing causes of the Emergency Charging (EC) pump A incident and has taken appropriate action to secure safety. I am also satisfied that the Licensee's proposed corrective action plan (and due dates), are appropriate to secure compliance and prevent recurrence of circumstances which may give rise to non-compliance. In line with ONR operational procedures and enforcement guidance I judge that formal investigation by ONR is not warranted nor is further enforcement action justified in relation to this incident.

An inspection of the BRWSS and HHSIS systems has raised a number of inspection observations of minor safety significance. These findings have been captured by the Licensee through condition reports and action requests for corrective action. However from the evidence sampled during the inspection my overall judgement is that the Systems, Structures and Components (SSCs) adequately fulfil the requirements of the safety cases and the Licensee is in compliance with the associated nuclear site licence conditions.

A meeting to discuss the forthcoming refuelling outage was constructive and provided a level of confidence in the Licensee's Internal Nuclear Assurance planned concurrence activities.

A discussion with the site trade union safety representative was useful and a number of matters were noted for further consideration at the next meeting.

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


From the evidence gathered during this intervention I conclude that no matters required immediate enforcement action or further enforcement decisions to be made. Corrective actions recorded under the Licensee's arrangements will be monitored by ONR on a routine basis.