In the accident at TEPCO's Fukushima Daiichi Nuclear Power Station, the Nuclear Regulatory Commission conducted a robot-based investigation at the Unit 2 facility, which appears to have a large amount of radioactive material attached, and measured high levels of radiation. ..

The Regulatory Commission is planning to investigate in detail in order to understand the impact on decommissioning work, considering that there is a source of strong radiation.

The Nuclear Regulatory Commission is the second of the three reactors that had a "meltdown" in which nuclear fuel melted down in the accident at the Fukushima Daiichi nuclear power plant. It was estimated that it was attached, and it was investigated using a robot from last month to this month.



What we investigated was a three-layer structure of a concrete "lid" with a thickness of about 60 cm called a "shield plug" above the reactor containment vessel, which was met on the 14th of the Regulatory Commission. The video of the survey was released at.



In the survey, when a radiation measuring instrument was placed in a 7 cm deep depression in the center of the lid, the value increased as it approached the bottom, and a high value of about 1.2 Sv per hour was measured.



The Regulatory Commission considers that there is a strong radiation source in the gap of the "shield plug", and that it may affect the work toward decommissioning, such as when removing "fuel debris" in which melted nuclear fuel is mixed with metal. We plan to investigate in detail in the future.