Office for Nuclear Regulation

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Hunterston B – System Based Inspection – SBI 03 (Boiler Feed Systems)

Executive summary

Purpose of intervention

The purpose of this intervention was to conduct a system based inspection of EDF Energy Nuclear Generation Ltd’s Hunterston B Power Station in relation to the Main Boiler Feed and Emergency Boiler Feed Systems. This was undertaken as part of a series of planned interventions that are listed in the Hunterston B Integrated Intervention Strategy (IIS) 2015/2016. The inspection was undertaken by the ONR Nominated Site Inspector, two Specialist Inspectors (Structural Integrity) and a Project Inspector.

Interventions Carried Out by ONR

We performed a safety case informed system based inspection of the Main Boiler Feed and Emergency Boiler Feed Systems. Through examination of these systems compliance inspections were performed against Licence Conditions (LC): 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 and radioactive waste). The inspections were based on sampling the implementation of the arrangements in place at the station against each licence condition.  The objective of the inspection was to determine whether the Licensee’s arrangements for plant operational limits, plant maintenance schedules, staff training requirements and third party inspection plans were in accordance with the system’s safety case requirements.

Explanation of Judgement if Safety System Not Judged to be Adequate

From this inspection, we judge that overall the safety provisions applicable to the Emergency Boiler Feed and Main Boiler Feed Systems inspected meet the requirements of the safety case and are adequate.

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

A system based inspection of the Main Boiler Feed and Emergency Boiler Feed Systems was carried out to judge the adequacy of the implementation of the station arrangements in place to ensure that relevant equipment can perform its’ requisite safety function. In deciding whether this safety system has been adequately implemented, I inspected compliance with the licence conditions detailed above. LC34 relating to leakage/escape of radioactive material and waste was deemed to be not applicable to the systems inspected and hence excluded from the scope of the inspection.

During the course of this system based inspection it was found that Hunterston B Power Station has arrangements to ensure that the Main Boiler Feed and Emergency Boiler Feed Systems are maintained and, as necessary, operated in accordance with its safety case. The arrangements were deemed to be implemented in an adequate manner, on the basis of those areas sampled during the inspection. The inspection identified potential areas for improvement however none gave rise to significant concern. Due to the limited significance of the observations I am content that NGL address these through their own arrangements.

In summary, the outcome from the system based inspection of the Main Boiler Feed and Emergency Boiler Feed Systems are that the arrangements and their implementation are deemed to be adequate, and therefore we have given an IIS rating of 3 (adequate) for LC28 and 3 (adequate) in respect of LCs 10, 23, 24 and 27.

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 undertaken against LCs 10, 23, 24, 27 and 28, it was considered that the Main Boiler Feed and Emergency Boiler Feed Systems met the requirements of the safety case.

There are no findings from this intervention that could significantly undermine nuclear safety.