Tokyo Electric Power Co. said Monday that radiation in the primary containment vessel of the No. 1 reactor of the Fukushima No. 1 power station gets as high as 9.7 sieverts per hour — enough to kill a human within an hour.
The radiation levels at six locations in the western section of the first floor of the PCV ranged from 7.0 to 9.7 sieverts per hour, the beleaguered utility said in disclosing data collected by a remote-controlled robot on Friday.
By contrast, the temperatures at the six locations monitored were cool, ranging from 17.8 to 20.2 degrees.
Tepco sent the robot into the primary containment vessel on Friday, expecting it to stay alive for 10 hours. But the robot failed within three hours after completing about two-thirds of its planned route. Tepco has given up on recovering the robot.
The survey involved eight Tepco employees and 36 other workers who were hired by contractors. The maximum radiation dose logged was 1.73 millisieverts.
Tepco official Teruaki Kobayashi said the survey found no major obstacles around an opening leading to the underground part of the vessel, which is good news for future surveys needed to extricate the molten nuclear fuel.
The No. 1 reactor is one of the three damaged by core meltdowns during the Fukushima nuclear crisis in March 2011.