Executive summary
Date(s) of inspection: February 2024
Aim of inspection
Observation of the annual level 1 demonstration exercise to confirm that Heysham 1's emergency arrangements remain effective.
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 demonstration exercise HARRIER at the EDF Energy Nuclear Generation Ltd (NGL) Heysham 1 Power Station.
The emergency scenario involved damage to the reactor pressure boundary resulting in its depressurisation. The reactor contained some failed fuel and so the resulting leaking carbon dioxide led to an off-site release of radioactivity. The Heysham 1 Emergency Control Centre (ECC) was rendered untenable by an unrelated electrical fire, requiring the use of the alternative ECC (AECC) which is located on the adjacent Heysham 2 Power Station site.
The licensee's emergency response achieved the following key outcomes:
- Established three on-site command centres (Central Control Room (CCR), ECC and Access Control Point (ACP)) together with support from the corporate Central Emergency Support Centre (CESC) located off-site near Gloucester.
- Completed a full site muster, accounting for all persons within an acceptable time-frame.
- Located, assessed, rescued and treated a casualty and handed-over this person over to ambulance personnel.
- Identified the presence of a potentially fatally-injured casualty and made an appropriate decision that this person could not be safely rescued (note areas for improvement below).
- Made timely and appropriate declarations of a Site Incident and Off-Site Nuclear Emergency (OSNE).
- Commenced the blow-down of the affected reactor through a filtered discharge route to reduce the ongoing radioactive release (note see areas for improvement below).
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 was adequate and we have awarded a green (no formal action) inspection rating against licence condition (LC) 11 (Emergency preparedness).
We agree with the two key areas for improvement as identified by the Emergency Arrangements Review Team (EART). These were associated with:
- Managing the situation in which there has been a potential fatality.
- Initiating the timely blowdown of a depressurising reactor with failed fuel to minimise the scale of an off-site radioactive release.
A number of minor areas for future enhancement were also identified.
Conclusion
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 was adequate and we have awarded a green (no formal action) inspection rating against licence condition (LC) 11 (Emergency preparedness).
We acknowledge the two key areas for improvement identified by the EART (see Observations/Advice) and have raised a level 4 regulatory issue (RI-11927) to track the licensee's actions to learn from and improve in these areas which we will follow-up on through normal regulatory business and future inspection activity.