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 2016/17.

Interventions Carried Out by ONR

This intervention included compliance inspections against the following Licence Conditions:

I undertook a review of the station's progress against its existing regulatory issues. I also attended a monthly update meeting with the station INA evaluators.

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

In relation to LC 26, I:

Observed the hierarchy of start-of-shift briefings from station management through to operations and conduct of control room operations. Overall I observed clear alignment of operational focus and safety critical activities.

Examined the station and company arrangements and their implementation associated with control of isolations (plant release) and return to service. I observed that the station's enhanced return to service arrangements following more complex plant modifications and maintenance are generally working well, and have matured over the past 2 years. However, based on a recent sample I observed anomalies and inconsistencies in the sign off for each of the three stages of plant maintenance and testing that indicate degraded rigour of procedural use and adherence. The station has self-identified this shortfall and committed to implement improvements.

Sampled the station arrangements for supervision and oversight of term contract partner activities undertaken on the station. The station's supervision of term contractors and oversight of role compliance appears to be mature with further integration of contract personnel into the station's fleet supervision arrangements.

In relation to LC 14, I:

Examined aspects of arrangements relating to the local production of safety case modifications and sampled their implementation through recent modifications executed under the stations' LC 22 arrangements.

Examined aspects of arrangements relating to authorisation of personnel undertaking station-based safety case management and production roles.

I observed that for a subset of category 3 safety cases, the station does not have adequate guidance to equip safety case authors with the necessary framework within which to justify that risks have been reduced to tolerable levels (Safety Assessment Principles Target 6). This appears to be particularly relevant in cases classified as category 3 but borderline with respect to category 2 where the rigour of guidance and training is much better defined centrally; in such instances there is also a step-reduction in rigour and extent of design authority verification and Independent Nuclear Assurance (INA) assessment through INSA (Independent Nuclear Safety Assessment). I have expanded an existing regulatory issue on this topic as the means by which to seek further improvement.

During this intervention I referred the station to ongoing concerns regarding need for improved proactivity from the station in managing regulatory issues. The station has committed to reinvigorate attention on issue management and resolution before the end of June 2016.

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

In relation to LC 26, I considered that an inspection rating of 'Green' is warranted on the basis that relevant good practice is generally being met, but with some minor contraventions of specific administrative requirements.

In relation to LC 14, I consider that despite the shortfalls in arrangements identified by this inspection I consider that an inspection rating of 'Green' is appropriate. This is on the basis that the arrangements for compliance with LC 14 at a local level are below standard for a small subset of instances; overall arrangements for safety case production are otherwise adequate. I discussed these shortfalls with the TSSM during the inspection debrief.

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