[NRG1973]

That one is easy. Concrete holds in heat, and right now the problem is getting heat out. Right now they need to keep as much of that material where it is as they can, and that means keeping those containment vessels and fuel pools intact.

If its such a bad strategy to entomb the reactors then why did they dod it so quickly in Chernobyl?

The truth of the matter is that the longer they take entombing the site, the more radioactivity will be emitted. Japan isn't as big a Russia and doesn't have as much space to relocate people to. They need to get this situation under control.

[GonzoGOP]

If its such a bad strategy to entomb the reactors then why did they dod it so quickly in Chernobyl?

Because Chernobyl had no containment vessel to begin with. The reactor core, not just some sheet metal like in Japan, had actually blown up and was spread out over the entire area. It was a desperation move because it was all they had left.

Think of it this way. First you try to save the ship, only then do you take to the lifeboats.