As disaster movies go, this is getting better and better.

There could be a very big and very real explosion of the tons of fuel melted together.

ITs called an excurison.   Isn't that sweet.

Its a brief runaway fission event

boom not BOOM RRRR like an A bomb but deadly in its own iminical way.
Take the 2000 tons of uranium ,
spread it big and quick or let it leak forever
no matter what all the kings horsemen and all the kings men try to do for the next 100 years...
those the sad and true realities.

Even the best possible outcome at this point is just awful.