The operator of the crippled Fukushima Daiichi nuclear plant says its latest estimation of the radiation level inside one of the reactors was extremely high and had the potential to be lethal to a human within a short period of time.
Tokyo Electric Power Company conducted an inspection inside the containment vessel of the plant's No.2 reactor last month using a remote-controlled camera, as part of a survey to scrap the reactor.
An analysis of the images found that the radiation was up to 530 sieverts per hour at a concrete cylinder supporting the reactor.
The level is enough to be lethal to a human within a short period of time, despite a possible error margin of up to 30 percent.
A survey conducted 1 year after the nuclear accident at a different part inside the same containment vessel logged 73 sieverts per hour.
In the latest estimation inside the vessel, the area near its opening logged 50 sieverts per hour at maximum.
The operator officials say that there are no leaks of gas with radioactive substances from the containment vessel.
Officials suspect that fuel debris; a mixture of nuclear fuel and melted parts of the reactor's facility, may be emitting strong radiation inside the vessel.
Some molten fuel penetrated the reactor's bottom and has reached the containment vessel as fuel debris.
The company plans conduct further inspections with a robot. There is a risk that some parts of the grating where the robot will be moving may be damaged by the high heat of the molten fuel.