BraveNewClimate’s March 15th thread has great information and I think they’ve answered (or at leasted addressed) your specific questions on the spent fuel pools.
http://bravenewclimate.com/2011/03/15/fukushima-15-march-summary/
As I read it ...they ingect Hydrogen as part of the process to control corrison ...newer designs have an automated way to handle that with noble metals....somehow.
need to read thru all of that again.