Spent fuel that’s been in a pool for 30 plus years will have minimal decay heat. It’s not zero. Buts it’s not the end of the world either.
Yah, that fuel is cold as a rock left out inna sun.
Did a study for the NSA back when the USSR fell apart and there was serious concern that nuke plant operators could get some money (since they weren’t being paid anymore) by selling old spent fuel to terrorists.
We looked at data from our own spent fuel, that had been in wet storage for years. Found that it was so cool (warm to touch, no burns) that a couple of guys could boost a few fuel elements in the back of a panel truck. Not much radiation, either.
As to Chernoble (sp?) there is back up diesel (oh, golly, global warming via fossil fuel!!!) for a day or two. Even Russians aren’t stupid enough to have missed that detail. This could go on indefinitely so long as diesel can be trucked in to refuel — just don’t tell Kerry. As to being off the grid, unless one of the three units is allowed to start up and push power out (they can’t generally operate at low enough power to just provide cooling) to the grid then they need to pull power in to continue cooling past the point when they run out of diesel.