Swimming Robot to be sent into Fukushima’s Flooded Reactors


The swimming robot developed by the Japan-based International Research Institute for Nuclear Decommissioning (IRID) in partnership with Toshiba.

It is ‘Little Sunfish’, or ‘mini manbo’. The robot, called an underwater ROV (Remotely Operated Vehicle), measures just 30 centimeters (11.9 inches) long and 13 centimeters (5.1 inches) wide. It consists front and rear-facing cameras and LED wires, powered by long wire. Five thrusters, four at the rear and one at the front, will help it steer through Fukushima.

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Engineers to send swimming robot into the radioactive waters of Fukushima, as they attempt to find material from the reactor. Little Sunfish to move into Unit 3 of the Fukushima Daiichi Nuclear Power Station. Three of Fukushima’s six reactors went into meltdown in March 2011, when a tsunami triggered by an earthquake struck the plant. About 160,000 people evacuated from nearby as a result of the radiation leak.

Sunfish can handle radiation levels of up to 200 Sieverts per hour

This reactor flooded with coolant up to a depth of about 6 meters (20 feet). Once operators trained, Little Sunfish sent into the flooded reactor at Unit 3 next month.

However, the clean-up process is not started until the melted fuel from all the reactors is found. Various efforts made to do this so far, with some material found earlier this year. Previous attempts to send robots into Fukushima have failed due to the high radiation levels.

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This latest robot is small enough to be able to swim into the flooded primary containment vessel (PCV) of Unit 3, where engineers have created a penetration hole 14 centimeters (5.5 inches) across. Little Sunfish can handle radiation levels of up to 200 Sieverts per hour. But some parts of the plant carry levels of up to 530 Sieverts per hour, more than enough to kill human.

As mentioned, though, this is just one small step in a very long process. Estimated it will take up until 2021 to find all of the melted fuel from the three reactors. After that, it will take another four decades to completely decommission Fukushima, at a cost of $188 billion.