A rock is shown inside the primary containment vessel of the No. 1 reactor at the Fukushima No. 1 nuclear plant in this image taken by a robot on 10 April 2015. How the rock got there is not yet known, but the robot lasted less than three hours in the deadly radioactive chamber. Photo: TOKYO ELECTRIC POWER CO. / KYODO

13 April 2015 (Japan Times) – 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. [more]

Radiation measured at deadly 9.7 sieverts in Fukushima reactor