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According to Keiji Miyazaki, professor emeritus of nuclear reactor engineering at Osaka University, the earthquake likely damaged the high pressure coolant injection system, part of the emergency core cooling system at Unit 3 (as we reported below, it already has been believed that Unit 1 suffered severe damage from the earthquake). This system is supposed to work to cool the reactor even if power is lost, but at Unit 3, it didn't. A review of pressure readings at Unit 3 indicate that there likely was a major steam leak that ultimately led to the speedy meltdown there. Article from Asahi.com here.
A rough translation of remarks by seismologist Katsuhiko Ishibashi (Emeritus Professor, Kobe University, which also suggest the earthquake itself heavily damaged the reactors, is available here.
Tomio Kawata, a research fellow of the Nuclear Waste Management Organization of Japan, said this week that the soil of a large area of northwest Japan - about 600 square kilometers - is contaminated with Cesium-137 at levels higher than prompted compulsory evacuation orders in the Soviet Union after Chernobyl (1.48 million becquerels per square meter). 700 square kilometers is contaminated with levels from 555,000-1.48 million becquerels per square meter.
Today, Tepco said that some 60 tons of radioactive water in one of its makeshift storage tanks - where it has been putting radioactive water gathered from the reactors and turbine buildings - has leaked out. The leak is apparently continuing.
Greenpeace is continuing its testing of marine life 12 miles and more from the Daiichi site, this week finding seaweed with contamination levels as high as 60 times legal limits.
UPDATE, 2:30 pm, Friday, May 20, 2011. The world's media are shocked (shocked, we tell you...) that three Fukushima reactors melted down. Where have they been the past 10 weeks? Where did they think all that radiation was coming from? You know, that radiation that has caused the evacuation/relocation of people as far as 25 miles from the reactor site? Not to mention contamination of food, seawater, etc.....
Even Tepco admitted weeks ago that 35-50% of the fuel had melted at the three reactors (U.S. Energy Secretary Steven Chu had estimated 70% melt at Unit 1); the big difference now is that it seems as if all the fuel has melted and is now a large glop at the bottom of each reactor building.
We expect the media to be equally shocked when they finally realize that the evacuees will never be returning home and that the world now has another piece of itself rendered uninhabitable by nuclear power.
In actual news, evidence is growing that Unit 1's meltdown was initiated by the earthquake and only exacerbated by the ensuing tsunami. Bloomberg reports that a radiation alarm inside Unit 1 went off before the tsunami even arrived, indicating coolant already had been lost and fuel melting had begun. If true, this could also require a re-assessment of how quickly reactors can melt down - that would mean meltdown had begun less than an hour after loss-of-coolant.
Masataka Shimizu, President of Tepco, resigned today after leading the company into the largest financial loss in Japanese history - about $15 Billion, and that's before any compensation has been paid to the tens of thousands of people who have lost their homes and livelihoods.
Woods Hole Oceanographic Institution says that the impact on the world's oceans by Fukushima exceeds the impact of Chernobyl - in fact, the impact is 10 times higher. Woods Hole has received an emergency grant from the National Science Foundation to set baseline radionuclide levels in both the Atlantic and Pacific Oceans and to monitor the impact of Fukushima fallout.
Recently released photos of the tsunami hitting Fukushima Daiichi are here.
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