Question...and I”m no scientist...but could they use supercooled items like Liquid Nitrogen or equvalent? Or would that not be a good combination with nuclear elements? and even if you were able to get LN02,how would you circulate it without power? I guess I just answered my own question but seawater doesn’t seem nearly cold enough all by iteslf. My prayers to the scientists and engineers obviously putting their lives on the line to control this.
A very-cold liquid like Liquid Nitrogen would flash to gaseous state immediately and cause an serious explosion. You want to use a coolant that stays in phase, a liquid that stays liquid or a gas.
Nope. It would just explode the unit and throw the fuel inside everywhere. You have to ramp things down smoothly as reactors are basically atom bombs in super slow motion so they can be kept in a feedback loop.
Normally some plants can take days or even weeks to fully shutdown and that is with full power, full staff, no earthquake/tsunami damage.
Right now they are dealing with damaged systems operating way outside any normal environment with limited resources.
The seawater and boric acid is a last ditch effort to avoid some local, albeit serious, contamination.