The Guardian’s Julian Borger has spoken to Mariana Budjeryn, an Ukrainian expert at the project on managing the atom at Harvard University’s Belfer Center.
Budjeryn said:
Saying that a reactor building is hit doesn’t tell us much, because the most vulnerable [part of] this is the electricity and water supply.
If the electricity is taken out, the back up generators kick in, but if those don’t kick in or their diesel fuel is set on fire, for example, the pumps can’t pump cold water into the reactor and into the spent fuel pools. That’s necessary to keep the nuclear reaction moderated. Otherwise the water will boil out and the core will go critical and explode.
If the core explodes, there’s hope that the confinement chamber will capture the radiation from release into the environment. Confinement chambers are designed with withstand some level of impact even bombing.
But of course we don’t know how they will stand to this intensity of shelling
BUT spent fuel pools - the fuel there is not as active, but they are usually overstuffed - so less active but more tightly packed material, also dangerous for going critical if the cooling system fails. And spent fuel pools are not covered by hardened concrete confinement chambers.
We learned about how vulnerable spent fuel pools are during Fukushima
The backup generators failed and the water pumping system failed - it was lucky that ocean water flooded those and the reactor cores to provide cooling.”
