The operator of the Fukushima nuclear power plant, Tokyo Electric Power Company Holdings Inc, has announced its plans to begin a trial retrieval of debris containing melted nuclear fuel from one of the three reactors that were severely damaged in the 2011 earthquake and tsunami. The company aims to retrieve a few grams of debris from the No. 2 unit in its first attempt, with plans to gradually expand the process to the No. 3 unit in the early 2030s.
Removing radioactive debris is considered one of the most challenging tasks in decommissioning the Fukushima Daiichi plant. The loss of cooling functions during the disaster led to severe damage in all three reactors. However, there are still uncertainties regarding how to remove an estimated 880 tons of debris from these reactors and where to store it until disposal.
To retrieve the debris, TEPCO plans to use a telescopic device equipped with a gripper tool that can extend up to 22 meters and access the debris through a penetration point into the primary containment vessel. Due to high radiation levels emitted by the debris, strong shielding measures will be implemented using connection structures and an isolation valve.
The retrieval operation is expected to take approximately two weeks once it begins after about a week for device setup. However, if radiation levels exceed 24 millisieverts per hour during retrieval, TEPCO will return the debris back into containment for worker safety.
The Nuclear Regulation Authority has approved this retrieval device on Friday, marking its readiness for trial retrieval operations. Originally planned for 2021, TEPCO had postponed this operation three times due to technical difficulties and challenges posed by COVID-19 pandemic restrictions.