Mar 28, 2012
Radiation levels inside Fukushima's reactor 2 have reached fatally high levels, and levels of water are far lower than previously thought, experts say today.
The current radiation levels are so high that even robots cannot enter. Tokyo Electric Power Co. (TEPCO) says that new robots and equipment will need to be developed to deal with the lethal levels of radiation.
TEPCO spokesperson Junichi Matsumoto told the Associated Press, "We have to develop equipment that can tolerate high radiation" when locating and removing melted fuel during the decommissioning.
At ten times the lethal dose, the radiation levels are at their highest point yet.
At the current level of 73 sieverts, the data gathering robots can only stand two to three hours of exposure. But, Tsuyoshi Misawa, a reactor physics and engineering professor at Kyoto University's Research Reactor Institute, told The Japan Times, "Two or three hours would be too short. At least five or six hours would be necessary." He added that "the shallowness of the water level is a surprise, and the radiation level is awfully high."
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The Japan Times: Reactor 2 radiation too high for access
73 sieverts laid to low water; dose too high even for robots
Radiation inside the reactor 2 containment vessel at the Fukushima No. 1 nuclear plant has reached a lethal 73 sieverts per hour and any attempt to send robots in will require them to have greater resistance than currently available, experts said Wednesday.
Exposure to 73 sieverts for a minute would cause nausea and seven minutes would cause death within a month , Tokyo Electric Power Co. said.
The experts said the high radiation level is due to the shallow level of coolant water -- 60 cm -- in the containment vessel, which Tepco said in January was believed to be 4 meters deep. Tepco has only peeked inside the reactor 2 containment vessel. It has few clues as to the status of reactors 1 and 3, which also suffered meltdowns, because there is no access to their insides.
The utility said the radiation level in the reactor 2 containment vessel is too high for robots, endoscopes and other devices to function properly.
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The operator of Japan's crippled Fukushima nuclear plant has said damage to one of the reactors is much worse than previously thought. [...]
On Tuesday workers managed to insert a probe into reactor number two for only the second time and found damage worse than expected.
Radiation was up to 10 times the fatal dose, the highest yet recorded at the plant. The level of water cooling the melted-down nuclear fuel was also far lower than expected.
The other two melted-down reactors, which are yet to be examined closely, could be in an even worse state, our correspondent adds.
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