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 to accurately gauge the situation 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.