Removal of Melted Nuclear Fuel at Fukushima Daiichi
The decommissioning of the Fukushima Daiichi nuclear power plant continues with the development of a specialized device to remove melted nuclear fuel debris. This device, resembling a fishing rod, will be used to "hook" tiny bits of fuel from the damaged reactors.
Plant operator Tokyo Electric Power Co. (TEPCO) plans to begin trial operations with the device in October 2023. The equipment was demonstrated to reporters in May, showcasing its capabilities for this delicate task.
Removing the melted fuel is considered the most challenging phase of decommissioning due to the extremely high radiation levels within the wrecked facility. TEPCO will initially focus on the No. 2 reactor, where radiation levels are relatively lower, aiming to remove a few grams of fuel debris.
The device, designed and built by Mitsubishi Heavy Industries Ltd., operates like a fishing pole. A 22-meter-long extendable pipe is inserted into a model of the reactor's pressure vessel pedestal. A claw-like arm at the end of the pipe is used to grasp the fuel debris, represented by pebbles in the demonstration.
An estimated 880 tons of fuel debris remain in the plant's reactors. The removal process was initially planned to begin in 2021 but was postponed due to the COVID-19 pandemic and mechanical issues. Additionally, the originally planned robotic arm lacked sufficient precision, leading to a change in the recovery method.
TEPCO will now begin with a simpler rod-style system before deploying the robotic arm at a later stage. This phased approach aims to ensure a safe and efficient removal of the melted nuclear fuel.