“What about using liquid nitrogren to cool them? Would that evaporate even quicker though?”
You would not want to do that for alot of reasons, the main one being that LN2 would instantly turn to its gas form and spread radioactivity into the air. In addition, putting something that cold onto something that hot might cause the fuel rod cases to crack.
You could have helped out “Bill Nye the Science Guy” on CNN yesterday. The commentator asked him why they couldn’t use liquid nitrogen to cool the fuel rods. Nye said that it was a problem of portability, that LN2 wasn’t very portable, and besides, when you’re talking about the extreme temperatures of fuel rods, there’s no appreciable difference in the cooling temperature of water as compared to LN2. That’s why, says he.
Of course, right after that, the commentator asked him about what caused the hydrogen explosion in plant #1. Nye said, and this is pretty close to an exact quote: “Hydrogen explosion? That doesn’t make any sense. Someone must have confused hydrogen with helium. There couldn’t be a hydrogen explosion, it must have been helium.”
Holy crap...all I know about generating nuclear power is what I’ve learned on the internet in the last couple of days and even I about choked on my beverage when I heard him say that. He’s CNN’s special, super smart, science guy who’s going to teach the audience all about nuclear power? OMG. I looked him up on wikipedia to see what his credentials were, and his highest level of education is a B.S. Degree.