Third robot to probe destruction following powerful 2011 earthquake and tsunami.
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Remote controlled robots are key to the decades-long decommissioning process, but super-high radiation and structural damage hampered earlier attempts to probe damage to the reactors from meltdowns following a massive earthquake and tsunami in March 2011.
The developers said Thursday they plan to send the probe into the primary containment vessel of Unit 3 at Fukushima this summer to study the extent of damage and locate parts of melted fuel that is thought to have fallen to the bottom of the chamber and been submerged by highly radioactive water.
The robot, about the size of a loaf of bread and mounted with lights, manoeuvres with tail propellers and collects data using two cameras and a dosimeter.
Japan hopes to locate and start removing the fuel after Tokyo’s 2020 Olympics.
The biggest challenge is removing hundreds of tons of melted nuclear fuel and debris from the plant’s three wrecked reactors.
Earlier, snake and scorpion-shaped robots became stuck inside two reactors. The scorpion robot’s crawling function failed and it was left inside the plant’s Unit 2 containment vessel. The other, designed for cleaning debris for the “scorpion” probe, was called back after two hours when two of its cameras stopped working after its total radiation exposure reached 1,000 Sievert — a level that would kill a human within seconds. The plan had been to use the robot for 10 hours at an exposure level of 100 Sievert per hour.
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Japanese officials say they want to determine preliminary removal methods this summer and start work in 2021. The decommissioning technology developers IRID and its partners have also designed some basic robots, including a “muscle” arm robot made by Hitachi-GE Nuclear Energy, and a different arm robot made by Mitsubishi Heavy Industries that are designed to approach the debris from the side of the reactors.
TEPCO is struggling with the plant’s decommissioning, and the cost for decommissioning Fukushima Dai-Ichi is now estimated at 8 trillion yen ($70 billion USD), four times an earlier estimate. Part of that cost will be included in Japanese utility bills.
Read more at Swimming robot to study damage at Japan’s Fukushima nuclear plant
