After losing its connection on August 20 to the only remaining 330 kV Ferosplavna-1 external power line, the Zaporizhzhia Nuclear Power Plant has maintained safety functions with emergency diesel generators for more than a week. The IAEA said that as of August 29, approximately 10 days of fuel remained for operating the emergency diesel generators.
Why is power still needed even though the reactors have stopped?
The Zaporizhzhia Nuclear Power Plant has not produced electricity since September 2022. However, the electricity needed to cool the reactors and spent nuclear fuel has not become unnecessary.
Emergency diesel generators supply power to essential safety functions, including:
- Pumps needed to cool the six reactors
- Pumps needed to cool the spent-fuel storage pools
- The plant’s essential safety functions
A plant that has stopped generating electricity is not the same as a plant that no longer needs cooling.
What exactly does ‘blackout within 10 days’ mean?
The IAEA said that the plant could face a complete site-wide blackout in approximately 10 days if external power is not restored or additional diesel fuel is not delivered in the near term.
Therefore, ‘blackout within 10 days’ is an outlook based on all of the following conditions continuing:
- External power is not restored
- Additional diesel fuel is not delivered
- Reliance on emergency diesel generators continues
This is not a confirmed announcement that emergency-generator fuel will be exhausted exactly 10 days later. Nor does it mean that a radiation release will occur within 10 days.
What has been confirmed at the site so far
The IAEA said it observed tens of tonnes of diesel fuel being transferred from two external locations to the Zaporizhzhia Nuclear Power Plant on August 28 and 29. It also said that radiation levels at the site were normal on August 29.
Meanwhile, the IAEA said that two plant workers were injured in a drone incident near the cooling pond on August 25. It reported additional drone incidents on August 26 at the dry spent-fuel storage facility and the spray systems for power equipment.
Key points to check now
Three aspects of the situation should be distinguished:
- External power: The loss, since August 20, of the connection to the only remaining external power line
- Emergency power: Diesel generators operating to cool the six reactors and the spent-fuel storage pools
- Risk outlook: The possibility of a complete blackout in approximately 10 days if additional fuel is not supplied and external power is not restored
The radiation levels reported by the IAEA are currently normal. However, whether external power is restored and additional fuel is delivered is a breaking-news situation, so these points should be checked again at the time of publication.