Office for Nuclear Regulation

System Based Inspection – SBI 26 – Auxiliary Shutdown  Room, Main Control Room and Alarm Display System

Executive summary

Purpose of intervention

The purpose of this intervention was to undertake licence condition (LC) compliance inspections at EDF Nuclear Generation Limited (NGL) Sizewell B power station in line with the inspection programme contained in the Sizewell B integrated intervention strategy (IIS) for 2015/16.

Interventions Carried Out by ONR

As part of this intervention, I carried out a system based inspection (SBI) of the auxiliary shutdown room (ASR), main control room (MCR) and alarm display system (ADS).  Through examination of this system I 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; 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.

This intervention also included a number of information gathering meetings with station personnel.  Other matters of a routine nature that are deemed unlikely to have a significant effect on nuclear safety, and which are being addressed routinely under the licensee’s arrangements, were also covered during the inspections.

Explanation of Judgement if Safety System Not Judged to be Adequate

From this inspection, I judge that overall the safety provisions applicable to the ASR, MCR and ADS meet the requirements of the safety case and are adequate. Further details are provided below.

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

A SBI of the auxiliary shutdown room (system RE), main control room (system RL) and alarm display system (system RK) was carried out to judge the adequacy of the implementation of station arrangements to ensure that the systems can perform their requisite safety function. In deciding if suitable and sufficient measures have been put in place for these systems, the inspection considers compliance with a number of licence conditions to test the adequacy of the arrangements implemented. The standard consideration of LCs during SBIs include LCs 10, 23, 24, 27, 28 & 34, with some added or excluded depending on their applicability. In this case, LC34 that relates to leakage and escape of radioactive material and waste is not applicable to this SBI and therefore has been deemed not applicable to the inspection.

During the course of this SBI it was found that NGL Sizewell B Power Station has adequately implemented their arrangements to ensure that the systems are maintained and operated in accordance with the safety case in the areas sampled during the inspection. The inspection identified a number of areas for potential improvement, and although none gave rise to significant concern, the station has agreed to take action to address them.

In summary, the outcome from the safety inspection of the ASR, MCR and ADS systems is that the arrangements and their implementation are deemed to be adequate, and therefore we have given IIS ratings of 3 (adequate) in respect of LCs 10, 23, 24, 27 and 28.

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 and 28, we considered that the ASR, MCR and ADS systems met the requirements of the safety case.

From the information gathered and evidence obtained during this intervention, no matters have 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 Sizewell B power station, set out in the integrated intervention strategy, should continue to be implemented as planned.