On Dec 9 I posted concerns about what looked like smoke visible on the Fukushima webcam http://majiasblog.blogspot.com/2012/12/fire-at-fukushima.html
Fukushima Diary reported that Ambassador Murata expressed concern recently about the cooling system at unit 4 being broken
Murata ex JP ambassador, “Coolant system of reactor4 was broken 12/8~12/11, concrete base is terribly deteriorating.”Posted by Mochizuki on December 11th, 2012
[Excerpted] According to Mr. Murata, former Japanese ambassador in Switzerland, the coolant system of SFP of reactor4 was stopped from 12/8 to 12/11, and the concrete base is terribly damaged already.
Majia here: A couple of days ago I noted that the fuel rods need not burn with fire to release radiation. The also release radiation through steam
April 1, 2011 in Science: "Pool at Stricken Reactor #4 Holds Answers to Key Safety Questions" by Eli Kintisch
[Excerpted] Lab experiments have shown that zirconium can burn either with steam or with oxygen. both reactions progress rapidly at roughly 800C; the former, crucially, releases hydrogen. The hydrogen explosion at reactor #4 points to the steam reaction, which releases less energy and therefore melts the fuel more slowly.... [end excerpt]
Majia here: I conclude that Tepco is having a difficult time keeping the fuel in unit 4 from burning with steam produced by the damaged rods (for info on damaged rods see here).
Fukushima Diary reports that Tepco is going to stop the cooling system at unit 4, which means we will probably see more off-gassing of radiation
Tepco to stop coolant system of SFP in reactor3 from 12/12 to 12/18 in the risk of aftershock after M7.4
Posted by Mochizuki on December 13th, 2012