From the NEI link above to their blog to this link on the right sidebar:
http://depletedcranium.com/best-sources-for-information-on-the-fukushima-nuclear-reactors/
per the LA times article the US believes that there are holes/cracks in the spent fuel pools caused by the explosions becuase in only a few days pure evoparation wouldn’t lower the pool to levels that they are now.
my thoughts:
perhaps more evidence of this is that the fuel pools in 5 and 6 aren’t having that many problems(only a slight rise in temps) despite also no have cooling pumps working