Reactor Core Melted Fully, Japan Says

TOKYO—Japan's tsunami-stricken nuclear-power complex came closer to a catastrophic meltdown than previously indicated by its operator—who on Wednesday described how one reactor's molten nuclear core likely burned through its primary containment chamber and then ate as far as three-quarters of the way through the concrete in a secondary vessel. Wall Street Journal (subscription required)

Update on December 1, 2011 by admin

Also see Yahoo News.

Update on December 1, 2011 by admin

The New York Times reports that Tokyo Electric Power Company (Tepco) has admitted for the first time that the melted core at its Unit 1 reactor at the devastated Fukushima Daiichi nuclear power plant has likely "bored" into the concrete floor of the primary containment, coming precariously close to an outer steel barrier, the final line of defense against even more catasatrophic radioactivity releases into the external environment. A critic describes Tepco's latest admission as "still an overly optimistic simulation." Hiroaki Koide, of the Kyoto University Research Reactor Institute, warns "I have always argued that the containment is broken, and that there is the danger of a wider radiation leak."

Speaking of overly optimistic nuclear disaster simulations, Greenpeace has strongly condemned Japanese government nuclear emergency preparedness for its inadequate "Speedi" radioactive plume computer code. The code only covers a 10 km area, whereas Greenpeace has documented Fukushima fallout 60 km downwind that should -- under international standards -- require evacuation of the population. Greenpeace also documents that actual nuclear catastrophes could be 10,000 times worse than those assumed by Speedi.

Update on December 1, 2011 by admin

The Asahi Shimbun also reported on this story. It reported that the Fukushima Daiichi Unit 1 reactor core had burned through 65 centimeters (25.6 inches) of primary containment structure concrete, leaving only 37 cm (14.6 inches) of concrete before a thin steel shell. Beneath that steel liner, a mere 7.6 meters (less than 25 feet) of concrete would remain before the molten core would reach earth below -- the very definition of "China Syndrome." Tepco assures that the 30 cm (11.8 inches) of cooling water at the bottom of the damaged primary containment structure will be enough to prevent further erosion, although it also admits many questions remain unanswered about where -- and how hot -- the molten fuel is.