In my view the water isn't really the thing to focus on here. Best case scenario, I guess we could assume normal atmospheric boiling point (100☌)? There were hundreds of tons of core material at temperatures near 1200☌, so worst case scenario you could assume all the steam becomes that temperature as the materials mix. I don't know what to assume the temperature of the steam is. I know a lot of it hinges on unknowns and the dynamics of the structures and materials involved, so I can simplify it to a constrained physics question:Īssuming 7,000 cubic meters of water instantly flashes to steam, how much potential energy is momentarily stored in that volume of steam occupying the same volume as the water did? Other sources vary wildly, some repeating the 'megatons' idea, and others saying it would've ' level 200 square kilometers'. I'm pretty sure this is absurd and impossible.

When the lava of the melted core hit it, it would cause an enormous steam explosion.įinally, my question: About how large would this explosion have been? The character in the show says '2-4 megatons' (of TNT equivalent, I assume). If anyone has a real figure, I'd love to hear). But at this point the decay heat and remaining fission reaction kept the core at more than 1200☌, causing it to melt through the concrete floors below the reactor.Īnd below the reactor were water tanks which contained 7,000 cubic meters of water (according to the TV show. This occurred after the initial explosion that destroyed the reactor, and after the fire in the core had been put out. So the second episode of the HBO series began to cover the risk of a steam explosion that led to them sending three divers into the water below the reactor to drain the tanks.

How big is steam