Executive summary
Date(s) of inspection: March 2024
Aim of inspection
The aim of this inspection is to observe a demonstration of the Hunterston B extant emergency arrangements to confirm they remain adequate.
Subject(s) of inspection
- LC11 - Emergency arrangements - Rating: Green
Key findings, inspector's opinions and reasons for judgement made
ONR observed and assessed the level 1 emergency exercise ‘OHIO’ at the EDF Energy Nuclear Generation Ltd. (NGL) Hunterston B power station.
The emergency scenario involved a seismic event during fuel handling operations causing a dropped fuel flask and damage to the pond water pipework in the active effluent treatment plant. This resulted in a drop in the pond water level and some localised flooding of boronated water into the active effluent treatment plant basement. Additional challenge was introduced by the Emergency Control Centre being rendered untenable because of severe water ingress and ongoing roof repairs and three missing/injured persons, one of which was a fatality.
The licensee's emergency response achieved the following key outcomes:
- Established three on-site command centres (Central Control Room (CCR), Alternative Emergency Control Centre (AECC) and Access Control Point (ACP)). In addition, the corporate Central Emergency Support Centre (CESC) was set-up to support the station.
- Completed a full site muster, accounting for site personnel in a timely manner.
- Located, assessed, and recovered two of the casualties.
- Located, assessed and isolated the casualty defined as a fatality in the exercise scenario.
- Assessed the conditions in the damaged area of the AETP and terminated the pond water leak.
- Assessed the conditions of the dropped flask.
ONR was satisfied that the exercise was appropriately challenging with suitable objectives, and that it was appropriately planned and executed. ONR judged that the licensee's performance met the legal requirements and we have awarded a GREEN (no formal action) inspection rating against licence condition (LC) 11 (Emergency arrangements).
Learning opportunities were identified in two areas, associated with:
- Crime scene management, where there has been a potential fatality.
- On-site medical treatment of contaminated casualties.
Conclusion
ONR judged that exercise ' OHIO ' met the legal standard for a demonstration of the licensee’s emergency arrangements and rated the inspection as Green (no formal action) against Licence Condition 11.