By YUSUKE OGAWA/ Staff Writer
October 2, 2025 at 18:55 JST
A micro-drone developed to survey the interior of the crippled Fukushima No. 1 nuclear power plant takes flight during a demonstration in Kashiwa, Chiba Prefecture, on Oct. 1. (Yusuke Ogawa)
Tokyo Electric Power Co. demonstrated micro-drones that will survey a destroyed reactor at the Fukushima No. 1 nuclear power plant and help determine an extraction method for tons of melted fuel there.
TEPCO showed a drone-training exercise to the media on Oct. 1 at a mock reactor facility in Kashiwa, Chiba Prefecture.
The drones, measuring 12 centimeters long, 13 cm wide and 4 cm high, weigh 95 grams. They are designed to operate in environments where radiation levels are too high for human activity.
They are expected to fly for 10 minutes and capture video footage inside the plant’s No. 3 reactor in November.
The No. 3 reactor is one of three that melted down after the nuclear plant was struck by the Great East Japan Earthquake and tsunami on March 11, 2011.
The footage collected will be used to create 3-D models of the reactor’s interior, helping engineers identify obstructions and assess structural damage before launching full-scale debris removal operations.
During the demonstration, two drones mounted on a platform were inserted into the reactor through a narrow 14-cm penetration hole. One of them lifted off, navigating around pipes and obstacles to showcase its maneuverability.
An estimated 880 tons of melted nuclear fuel and structural materials remain in the three damaged reactors at the Fukushima plant.
Removing this massive volume of highly radioactive debris is considered the most difficult phase of the plant’s decommissioning.
To study the composition of the melted fuel, TEPCO extracted 0.9 gram of corium from the No. 2 reactor over two attempts.
In July, TEPCO proposed a method for large-scale debris removal from the No. 3 reactor. The plan involves inserting a rod-like device from above to break up the debris inside the pressure vessel, then vacuuming it out from the side.
Preparations for the operation are expected to take 12 to 15 years, with full-scale work beginning no earlier than fiscal 2037.
TEPCO officials say the drone footage will be critical in determining whether the planned extraction method is feasible.
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