Office for Nuclear Regulation

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Hunterston B - Planned Intervention

Executive summary

Purpose of intervention

The purpose of this intervention was to undertake Licence Condition (LC) compliance inspections at EDF Energy Nuclear Generation Ltd’s (NGL’s) Hunterston B power station, in line with the planned inspection programme contained in the Hunterston B Integrated Intervention Strategy (IIS) for 2015/16.

Interventions Carried Out by ONR

This intervention included compliance inspections against the following Licence Conditions:

The intervention was undertaken by four ONR inspectors and involved the annual Level 1 demonstration (Exercise ‘Dunlop’) of the on-site emergency response arrangements at the Hunterston B nuclear licensed site, in compliance with the requirements of LC 11(5). The purpose was to seek assurance that the licensee’s emergency arrangements and its emergency response personnel have the capability to deal effectively with any accident or emergency arising on the site and their effects.

During this visit, I undertook an unannounced, out-of-hours inspection of the Reactor 3 and Reactor 4 gas circulator halls. I also met with the portfolio projects manager to examine progress in the refurbishment and commissioning of the station CO2 system.

I also attended a monthly update meeting with the station Independent Nuclear Assurance evaluators and discussed ONR’s inspection plans for the 2016/17 year.

Explanation of Judgement if Safety System Not Judged to be Adequate

Not applicable as no system inspection was undertaken during this intervention.

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

Prior to the intervention, NGL provided details of the exercise scenario and provided a pre-brief that captured the work undertaken over the previous year as well as an overview of the exercise objectives.

During the course of the exercise a number of opportunities for improvement were identified. ONR will write to the station within 28 days of the demonstration detailing its observations in full. ONR considered that the joint debrief meeting, attended by station, Independent Nuclear Assurance and ONR, provided a comprehensive exchange of information on the outcome from the exercise.

During the out-of-hours inspection I examined completed work order cards for routines scheduled for that shift; all were completed to the correct standard. I observed configuration control shortfalls in the Reactor 3 gas circulator hall, details of which have been reported to the station. During my visit to the central control room I observed that the shift logs were appropriately informative on plant status and had appropriately conservative decision making during load raising operations.

We observed that satisfactory progress is being made in the refurbishment of the station CO2 system since the previous inspection undertaken in December 2015. The station is close to determining the final design and, despite some minor slippage in the construction schedule, has implemented recovery initiatives to ensure handover to operations by June 2017.

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

The ONR team considered that Exercise ‘Dunlop’ provided an adequate demonstration of the station emergency arrangements for the current year and that the station responded well to the scenario. This inspection has been allocated an IIS rating as ‘3 – Adequate’.

There are no findings from this inspection that could significantly undermine nuclear safety.  Therefore we consider that no additional regulatory action arising from this visit is necessary currently, and the interventions for Hunterston B power station, set out in the integrated intervention strategy, should continue to be implemented as planned.