Bloomberg has an update on the Fukushima nuclear disaster - Radiation Readings in Fukushima Reactor Rise to Highest Since Crisis Began. Weirdly this story has changed since it was first published, which initially claimed radiation readings had fallen to zero - http://www.bloomberg.com/news/2011-04-27/tokyo-water-radiation-falls-to-zero-for-first-time-since-crisis.html.
Radiation readings at Japan’s Fukushima Dai-Ichi station rose to the highest since an earthquake and tsunami knocked out cooling systems, impeding efforts to contain the worst nuclear crisis since Chernobyl.
Two robots sent into the reactor No. 1 building at the plant yesterday took readings as high as 1,120 millisierverts of radiation per hour, Junichi Matsumoto, a general manager at Tokyo Electric Power Co., said today. That’s more than four times the annual dose permitted to nuclear workers at the stricken plant.
Radiation from the station, where four of six reactors have been damaged by explosions, has forced the evacuation of tens of thousands of people and contaminated farmland and drinking water. A plan to flood the containment vessel of reactor No. 1 with more water to speed up emergency cooling efforts announced yesterday by the utility known as Tepco may not be possible now.
“Tepco must figure out the source of high radiation,” said Hironobu Unesaki, a nuclear engineering professor at Kyoto University. “If it’s from contaminated water leaking from inside the reactor, Tepco’s so-called water tomb may be jeopardized because flooding the containment vessel will result in more radiation in the building.”