> Perhaps read the source I linked you? The redacted Japanese one, or the Wikipedia article? The Wikipedia article doesn't contradict me. It says "serious exp

> Perhaps read the source I linked you? The redacted Japanese one, or the Wikipedia article? The Wikipedia article doesn't contradict me. It says "serious explosion", but nothing about kilotons, and says "would eject more material" but nothing about a large area. That's a reasonable estimate. > you don't need a containment vessel to create a large steam explosion. You said a "kiloton level" explosion. That does require containment. > If you drop gigawatts of thermal energy into a body of water Before it melted entirely through, the concrete it was melting would be hot enough to boil the water on the other side. That steam would have been uncontained and would have vented out of the entrances to the basement, blowing doors open if needed. Based on how slowly the molten core was progressing downward this likely would have removed a fair bit of water before it actually melted through and began boiling the water rapidly. And then, have you ever seen someone stick their hand (quickly) in liquid nitrogen or molten lead (done with a wet hand)? The Leidenfrost effect limits the contact with a layer of steam. You can't transfer those gigawatts straight into the water all at once. And while you're waiting, the steam is venting up through the new hole in the ceiling. Without a sudden, contained, steam generation event the further core ejection would be limited if it happened at all.