The world looked on in shock as Russian troops rained bombs down on the Zaporizhzhia nuclear plant in Ukraine, Europe’s largest nuclear reactor.
But what could have happened, and is there a danger of a nuclear disaster?
Here, atomic energy specialist Professor Robin Grimes, who previously advised the UK’s Ministry of Defence, and former nuclear scientist Cheryl Rofer, who worked for the US government’s Los Alamos National Laboratory, and spent 35 years clearing up nuclear sites in the former Soviet Union, answer your questions.
How many nuclear power stations are there in Ukraine?
Four, as well as the now-retired Chernobyl : Zaporizhzhia; Khmelnytskyi Nuclear Power Plant in Netishyn and Rivne Nuclear Power Plant in Varash, both west Ukraine; and the South Ukraine Nuclear Power Plant in Yuzhnoukrainsk, south Ukraine.
They need that many because that’s how 51% of its power is generated. They are third most nuclear dependent nation, after France (70%) and Slovakia (53%).
How big are they?
Zaporizhzhia has six light water reactors. The other three have nine between them. Chernobyl had four.
If any of the reactors in the plants are hit by a rocket, could it cause a nuclear explosion?
Ms Rofer says: “The reactors all have outer concrete containment structures that can sustain a hit from a 20-tonne airplane.
There is no way to cause a nuclear explosion - like a nuclear bomb - with reactors.”
What could happen?
Ms Rofer says: “The worst would be a fire in the spent fuel storage pools. This would release radioactive material into the atmosphere. The effects would be mostly local, within tens of miles. Some material might be carried on the winds, which, in that part of the world, are usually toward Russia.”
How would an explosion at Zaporizhzhia compare with Chernobyl?
Prof Grimes says: “Claims it would be many times greater than Chernobyl are ridiculous. Zaporizhzhia has about the same amount of nuclear material as Chernobyl did.”
What’s the process of turning off the plants?
Ms Rofer says: “I think all the reactors but one at Zaporizhzhia have been shut down but they still require cooling water. Shut down reactors are slightly less dangerous, but leaks and fires are still possible.”
Prof Grimes adds: “The way to be safe is to put all reactors into ‘cold shutdown’ [when a coolant is added to keep it below 93C]. Then you can walk away for months.”
