'Melt-through' at Fukushima? / Govt report to IAEA suggests situation worse than meltdown

The Yomiuri Shimbun

Nuclear fuel in three reactors at the Fukushima No. 1 nuclear plant has possibly melted through pressure vessels and accumulated at the bottom of outer containment vessels, according to a government report obtained Tuesday by The Yomiuri Shimbun.
A "melt-through"--when melted nuclear fuel leaks from the bottom of damaged reactor pressure vessels into containment vessels--is far worse than a core meltdown and is the worst possibility in a nuclear accident.
The possibility of the situation at the plant's Nos. 1 to 3 reactors was raised in a report that is to be submitted to the International Atomic Energy Agency.
If the report is released as is, it would be the first official recognition that a melt-through has occurred.