Fukushima: causes of largest radioactive leaks may be found
"Among the 4 reactors at the Fukushima plant, the No. 2 reactor leaked the largest amount of radioactivity according to nuclear disaster monitoring.
Researchers from the University of Tokyo, the Japan Atomic Energy Agency and other experts have examined the crisis response log at the reactor facility. They also checked radiation levels in surrounding areas.
They found radiation levels rose sharply 3 times at monitoring posts 10 kilometers south of the plant over a period of 5 hours during the night of March 14th.
These rises came 1 hour after each time workers at the No. 2 reactor released steam from the core to lower its pressure. The plant employees did so to protect the reactor.
But it is believed that by that time the nuclear fuel in the core had already melted down and its containment vessel was also full of radioactive substances.
The experts assume that the radioactive plume escaped from cracks in the containment vessel after steam was released from the core. It was carried south by the wind.
They say the amount of the radioactivity leaked from the No. 2 reactor was 10 to 20 times higher than other reactors, following their hydrogen explosions."
http://www3.nhk.or.jp/daily/english/20120724_26.html
Researchers from the University of Tokyo, the Japan Atomic Energy Agency and other experts have examined the crisis response log at the reactor facility. They also checked radiation levels in surrounding areas.
They found radiation levels rose sharply 3 times at monitoring posts 10 kilometers south of the plant over a period of 5 hours during the night of March 14th.
These rises came 1 hour after each time workers at the No. 2 reactor released steam from the core to lower its pressure. The plant employees did so to protect the reactor.
But it is believed that by that time the nuclear fuel in the core had already melted down and its containment vessel was also full of radioactive substances.
The experts assume that the radioactive plume escaped from cracks in the containment vessel after steam was released from the core. It was carried south by the wind.
They say the amount of the radioactivity leaked from the No. 2 reactor was 10 to 20 times higher than other reactors, following their hydrogen explosions."
http://www3.nhk.or.jp/daily/english/20120724_26.html