Tokyo Electric Power Co (Tepco) is to begin a demonstration project to remove a small amount of radioactive debris from unit 2 of the Fukushima Daiichi NPP which suffered a reactor meltdown after the March 2011 earthquake and tsunami. The debris is a mixture of molten nuclear fuel and parts of the reactor structure.
Removal of the debris has proved challenging, requiring the development of a special robotic arm to extract radioactive fuel, metal cladding and other structures from the reactor. Tepco originally planned to begin retrieval of the debris in 2021 but delayed the start of procedure pending development of the technology and regulatory approvals. Japan’s Nuclear Regulation Authority recently issued a certificate, certifying safety, after conducting a pre-operation inspection.
About 880 tonnes of fuel debris remain in the three reactors that suffered a meltdown, according to estimates by the International Research Institute for Nuclear Decommissioning. This initial demonstration will retrieve less than 3 grams of the material, which will be analysed for its composition and hardness, providing essential data for the full-scale removal process.
A robotic arm resembling a fishing rod will be operated remotely enabling a metal claw-like grip to be lowered down to retrieve a small amount of debris, the company said on its website. It is expected to take several days for the device to reach the bottom of the containment vessel, where the fuel debris is located. Tepco has selected unit 2 to demonstrate the method and plans to remove debris units 1&3 in the future.
It is estimated that the clean-up at Fukushima will cost around JPY23,000bnn ($157bn). The government and Tepco are aiming for the decommissioning of the plant to be completed between 2041 and 2051.
