The operator of the crippled Fukushima Daiichi nuclear power plant says a robotic survey of fuel debris at the No. 1 reactor is being hampered by plumbing and other structures. The utility says it will extend the probe by one day, until Wednesday.
So far engineers have detected strong radiation of about 11 sieverts per hour in the water inside the containment vessel.
Tokyo Electric Power Company on Saturday started sending a remote-controlled robot into the reactor’s containment vessel to look at the state of debris — a mixture of melted fuel and reactor parts. The robot is equipped with a camera and a dosimeter.
The melted fuel is believed to still be at the bottom of the vessel, where about 2 meters of contaminated water accumulates.
TEPCO released the results of the ongoing survey on Tuesday. It said the robot moved to a location believed to be just above the debris and lowered the camera and dosimeter into the accumulated water.
The dosimeter detected radiation of 6 sieverts per hour one meter from the bottom. But piping prevented the device from reaching deeper, and it has yet to confirm the debris.
TEPCO also said the robot recorded about 11 sieverts of radiation per hour about 30 centimeters from the vessel’s bottom at another location. Officials believe the radiation may be coming from contaminated fragments that fell to the bottom, as they expected no debris there.
Through the extended probe, TEPCO hopes to collect more data on conditions inside the vessel.