This video from Japan says about itself:
Radioactive Water: Fukushima Daiichi’s Hidden Crises
As one of the engineers says we don’t know how we can stop the flow of contaminated water.
This documentary explores the men working in unit-1 reactor, exposing themselves to high doses of deadly radiation. When ask about units 2 & 3 they say we have no idea what’s going on in them because the radiation levels our so high they can’t go in them.
Speculation is the cores in units-2 & 3 have burned through the containment vessels and burned its way deep into the earth. If this theory is right there’s no chance to recover the molten corium.