Office for Nuclear Regulation

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Hinkley Point B planned interventions - System Based Inspection SBI-026 - Reactor Shutdown Sequence Equipment

Executive summary

Purpose of Intervention

The purpose of this intervention was to undertake a system based inspection (SBI) of the reactor shutdown sequence equipment at EDF Energy Nuclear Generation Limited's (NGL's) Hinkley B power station in line with the planned inspection programme contained in the Hinkley B integrated intervention strategy (IIS) for 2017/2018.

Interventions Carried Out by ONR

The nominated ONR site inspector for Hinkley Point B and three ONR control and instrumentation (C&I) specialist inspectors undertook a system-based inspection of the reactor shutdown sequence equipment to judge the system performance against its safety function. Through sampling of documentation, plant walk down and discussions with staff, we examined NGL's compliance with the following nuclear site licence conditions (LCs), which are applicable provisions of the Energy Act 2013:

We judged that LC34 (Leakage and escape of radioactive materials) was not applicable to the system under consideration for the purpose of this inspection.

During the intervention week, the Site Inspector also undertook a number of additional engagements with the station staff on the following topics;

Hinkley Point B Alcohol & Drugs Policy following a complaint from a member of the public.

The nominated site inspector also attended the Hinkley Site Stakeholder Group (SSG) meeting.

The intervention was performed in line with ONR’s guidance requirements (as described in our technical inspection guides) in the areas inspected.

Explanation of Judgement if Safety System Not Judged to be Adequate

From the system-based inspection, we judge that the implementation of the arrangements for the reactor shutdown sequence equipment meet the requirements of the safety case.

Key findings, inspectors' opinions and reasons for judgements made

Based on the areas sampled during this system-based inspection, we judged that the licensee has implemented adequate arrangements to ensure that the reactor shutdown sequence equipment is maintained and operated in accordance with the safety case. This was supported by observations made by ONR inspectors during the plant walk down and discussions with the licensee's staff.

The inspection identified a number of areas of good practice which had resulted in an improved performance of the system in the period between 2011 and 2017, which provides a positive indication of the effectiveness of maintenance activities and training related to the reactor shutdown sequence equipment. The discussions with operators and the training department also provided confidence that the operating instructions associated with the plant after shutdown (both with and without RSSE available) are adequate and effective.

We noted areas for improvement with respect to minor inconsistencies in the maintenance records (e.g. signoff process, approval of minor out-of-tolerance results and coverage of tests for alarms). Moreover, the licensee should consider revising their strategy for monitoring equipment degradation trends to identify ageing mechanisms that are taking place that could lead to failure of components and equipment. In addition, clarify the rationale supporting the selective protection of reactor shutdown sequence equipment cabinets from water ingress. A regulatory issue has been raised to track progress against the actions raised with the licensee.

Overall we judged that the arrangements in respect of the reactor shutdown sequence equipment generally met relevant good practice and therefore we have given an intervention rating of green in relation to compliance with LCs 10, 23, 24, 27 and 28.

Conclusion of Intervention

From the targeted sampling of documentation, discussions with the licensee staff and the plant walk down during this SBI; we consider that the reactor shutdown sequence equipment met the requirements of the safety case.

There are no findings from this inspection that could significantly undermine nuclear safety. At present, no additional regulatory action is needed over and above the planned interventions at the Hinkley Point B Power Station