Jack-

"Would any reactor anywhere in the world do much better if it was abruptly taken off the grid with fuel supplies cut off?"

The short answer is a resounding "NO!"

But the nuclear industry has always assured its critics that each nuclear plant has layers of back-up systems and such a total cut-off of external power is a highly unlikely event. Hell, our nuclear plants typically only had 4 hours of back-up battery power.

mg-

"why contaminated water cannot be used to cool rods off."

It can and eventually it will be used. I'm not sure why they aren't able to do that now. It needs to be collected in a pool or tank and then recirculated. This is only useful if the water is only contaminated with low-level radiation.

Charley Noble