Yesterday I posted my suspicion that TEPCO is encountering problems with the melted fuel based on a number of observations, including the flashing (warning?) light, police car at the Futaba intersection with lights on, and the boat in Daiichi's harbor.
Today I watched a major 30 minute steam "event" (in my opinion). I call this a steam event rather than a natural "fog" event because of the way the steam moved so quickly and the manner whereby it rose from the ground at the Daiichii site.
Here are a few screen captures. You can see more at this link: