Fukushima warning: danger level at nuclear plant jumps to 'serious'
Source: Guardian
The new warning, expected on Wednesday, comes only a day after the nuclear watchdog assigned a much lower ranking when the plant's operator, Tepco, admitted about 300 tonnes of highly toxic water had leaked from a storage tank at the site.
The Nuclear Regulation Authority has now said it will dramatically raise the incident's severity level from one to three on the eight-point scale used by the International Atomic Energy Agency (IAEA) for radiation releases. Each single-digit increase in the scale actually represents a tenfold increase in the severity of a radiological release, according to the IAEA.
...The leak is the single most dangerous failure at the plant since the 2011 meltdown, which warranted the maximum level of seven on the severity scale, putting it on a par with the Chernobyl disaster 25 years earlier.
"Judging from the amount and the density of the radiation in the contaminated water that leaked ... a level three assessment is appropriate", the NRA said in a document posted on its website on Wednesday.
Read more: http://www.theguardian.com/environment/2013/aug/21/leap-fukushima-danger-ranking
The article states that (contrary to some claims on DU) they still do not know the cause of this leak.
= new reply since forum marked as read
Well, that's just adorable. 
because it was a prediction that the Japanese government would revise the threat level. FWIW, my prediction was correct and the threat level became more severe.
Whether anyone else approved of the comment isn't within my control. One of the approving remarks occurred before this OP thread started while the other approving remark appeared as a response afterwards. Unless you think that an "I told you so" comment is meant to be "adorable", there wasn't any intention on my part to be "adorable".
However, I'll take the high road and apologize if I offended your sensibilities. However, I'll make another prediction to state that if you are so easily offended and call out DUers that have been here for years, then you probably aren't going to last long at DU.
BTW, welcome to DU. 
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That's the way we roll ...
Essentially Radioactive self-heating Lava
From Chernobyl:
Here is one of many many papers on Fukishima...
There was an estimated 50 tons of reactor fuel and 800 tons of graphite left in the reactor at Chernobyl after the explosion there.
Fukushima has an estimated 70 tons of fuel in unit 1 and 90 tons of fuel in units 2 and 3. It is not known how much was ejected in the explosions at Fukushima.
For a grand total of 250 tons of fuel at Fukushima, dwarfing Chernobyl.
http://www.houseoffoust.com/fukushima/corium/corium.html
Corium Lava can melt a foot of concrete per hour — Cooling with water may not stop ...
Researchers at the Argonne National Lab created corium in the laboratory
They found that corium lava can melt upwards of 30 cm (12″
of concrete in 1 hour
This is why it is so important to know if a nuclear reactor accident has gone into true “meltdown” as the corium lava will rapidly melt its way through the inner containment vessels (or more) in a matter of hours unless it can be cooled again. However, results from these CCI (core-concrete interaction) experiments, suggest that cooling with water may not be sufficient to stop corium from melting the concrete.
One thing to remember — much of the melting of concrete during a meltdown occurs within minutes to hours, so keeping the core cool is vital for stopping the corium for breaching that containment vessel.
Now, this lava is, of course, very different than the lava that erupts from a volcano, compositionally.
The fuel pellets inside the fuel rods are almost entirely UO2 while the fuel rods in which the pellets are placed is made of zirconium alloys. As the fuel rods heat in an accident, they can get hot enough to start bending (close to 700°C) and if the pellets inside the casing touch, they can begin to melt if the temperature reaches ~1200ºC*. The heat can continue building as the fuel rods melt, eventually forming an entirely molten body that is a mix of the UO2 from the fuel pellets and the zirconium alloy of the casing.
probably stored right next to the beach front reactor 
