Office for Nuclear Regulation

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Hunterston B - Planned Inspection

Executive summary

Purpose of intervention

The purpose of this intervention was to undertake a system based inspection at EDF Nuclear Generation Limited’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.

The inspection was undertaken by the nominated site inspector, the nominated site inspector – designate and a specialist structural integrity inspector.

Interventions Carried Out by ONR

During this intervention, the following Licence Condition (LC) inspections were undertaken:

Also during this intervention, we met with the station’s independent nuclear assurance evaluators (INA) to review and discuss matters of safety. During this visit, the nominated site inspector and designate undertook familiarisation visits, site induction training and meetings ahead of assuming the post on 1st April 2017. Also during this visit, we attended the Hunterston site stakeholder group meeting on 2nd March 2017, held at Lauriston hotel in Ardrossan.

Explanation of Judgement if Safety System Not Judged to be Adequate

There was no system based inspection undertaken during this intervention.

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

During this intervention, a specialist structural integrity inspector undertook follow-up enquiries into a site incident which occurred in December 2016 involving a pipe hanger failure. The specialist inspector reported that a draft investigation has been completed for this event and is due for presentation to the station Corrective Action Review Board (CARB) in the near future. Root cause is identified as poor quality control during original construction. The station demonstrated there were around 160 hangers which had been subject to a visual inspection since the event. However, it was not possible to get close enough to around 108 of these in order to establish whether there were hidden joints of a similar construction. A programme of work was in place to access these for a closer inspection which is expected to be completed by June 2017. The visual inspections to date have not identified any further hangers with a similar construction.

In view of the adequate investigation undertaken by the station, it is recommended that no formal investigation is considered to be warranted. Notwithstanding this, and noting the potential for serious personal injury to have occurred as a result of this incident, it is considered appropriate to apply the ONR Enforcement Management Model, and to record this outcome via a decision record.

Also during this intervention a follow up inspection was undertaken into an incident involving a turbine hall crane collision (which occurred in February 2016). Assurance and evidence were sought that corrective actions identified during the crane incident were duly completed and to ascertain the adequacy of the investigation into the hanger failure to establish whether further formal investigation was required. The specialist inspector was satisfied that the corrective actions identified within the station’s own investigation have been completed, with the exception of one action (to undertake an effectiveness review) which has a completion date of April 2017. There is sufficient evidence that the requirements for an ONR letter previously sent to the station have now been addressed and the associated regulatory issue may now be closed.

I undertook a joint LC 32 / RSA(93) compliance inspection with the SEPA site inspector, during which we examined the following aspects of waste management on the power station:

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

From the evidence gathered during this intervention, we allocated ‘Green’ ratings for LC 7 and LC 32.

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