AP reports, citing Chief Cabinet Secretary Yukio Edano, that the fuel rods appear to be melting in three of the most troubled reactors.
Although we cannot directly check it, it's highly likely happening.
No specifications are provided about which are these three reactors but I understand that this refers to the three reactors of Fukushima I (or Daichi), all of which were already in dire straits.
Other three nuclear plants in NE Japan have been reported as damaged, though their situation is not yet known to be so severe.
Found via Florida Oil Spill Law. Other relevant reports mentioned:
Also, air view (from FOSL):
|Fukushima I overhead view after explosions (click to expand)|
From bottom left to up-right you can see reactor 1 (top broken), reactor 2 (intact in the outside) and reactor 3 (the only one working with plutonium, highly damaged and smoking). The reactors at the top right (no. 4 is visible) were not operative when the earthquake and tsunami hit.
Update: habemus Chernobyl:
Reactor 4 (idle at the time of the tsunami) is also affected, as the spent fuel pond has caught fire. This underlines, I believe, how extremely demanding (and hence costly) is the nuclear option, where even idle stuff is extremely dangerous.
But even more severe is that the International Atomic Energy Agency (IAEA) has acknowledged that radioactivity is being directly released to the atmosphere at extremely high doses of up 400 milliSievert (mSv)per hour, equivalent to 40,000 milirems or 40 rems per hour. For comparison the usual background radiation is of 2.4 mSv per year or about a millesimal fraction of a millirem per hour. So the emissions may be of the order of a million times the normal background radiation.
This emission of radiation was acknowledged only after the remaining active reactor at Fukushima I plant exploded in what has been claimed to be another hydrogen explosion. However, I have the impression that the explosion at reactor no. 3 may have been the worst one, as it was a huge explosion that left the building utterly destroyed (see photo above).
In a related development, the Japanese Nikkei index fell down 13% yesterday in spite of all the preventive exercises of the Central Bank.
An animated image from Der Spiegel shows that the plume is mostly blowing towards the Ocean (and hence towards North America eventually, even if it should arrive in a reduced concentration) but that now and then it goes to other directions, quite worryingly to the South-SW, right over Tokyo and its metropolitan area (today), where 35 million people live and where all government and most economical institutions have their seats:
If this is accurate, today Tokyo is being radiated in full. I wonder how people will react to this information when they get it, as they will surely.