The removal of melted fuel rods from the Fukushima Daiichi NPP destroyed by the 2011 earthquake and tsunami will be deferred until around October, Tokyo Electric Power Co. Holdings (Tepco) said, citing delays in completing a robot arm for the task.

Fuel debris removal was originally scheduled to start within a decade of the 2011 reactor meltdowns, but development and testing of a robot arm in the UK was delayed by COVID-19, initially postponing the work until 2022 and then to the latter half of fiscal 2023. Akira Ono, Tepco official in charge of decommissioning efforts, told a news conference that the delays were due to problems with deposits near the reactor entrance, as well as "the need to improve the safety and operability of the robot arm”.

The huge robotic arm, 18 metres long and weighing 4.6 tonnes, was developed by Japan’s International Research Institute for Nuclear Decommissioning (IRID), Mitsubishi Heavy Industries (MHI) UK’s Veolia Nuclear Solutions (VNS). It was delivered to MHI’s Kobe facility for testing in July 2023.

An estimated 880 tonnes of radioactive debris is in reactor units 1-3 comprising fuel and other materials that melted, cooled and solidified after the plant lost power following the tsunami. Debris removal is viewed as the main challenge in decommissioning. Tepco plans to start with unit 2. However, before the melted fuel can be tackled, melted equipment and other detritus must be removed. Tepco began this work in January using low-pressure water and other tools but is unclear how long it will take.

A revised approach will use a new method of retrieval using a telescopic tube first instead of a robotic arm, but this still requires approval from the Nuclear Regulation Authority. Tepco will attempt to use this device to take out the melted fuel around October. The robot arm is expected to take about 90 days to clear a path to the debris.

The government has spent JPY7.8bn ($52.8m) to develop the robot arm and the delays put at risk the decommissioning target year of 2041 to 2051. Decommissioning and compensation costs are expected to increase beyond the current estimate of JPY23,400bn.

Image (top): The robotic arm designed to remove fuel debris from the Fukushima Daiichi nuclear plant

Image (right): The melted fuel debris