An attempt to use an extendable robot to remove a fragment of melted fuel from a wrecked reactor at Japan’s tsunami-hit Fukushima Daiichi nuclear power plant was suspended on Thursday due to a technical issue.
The collection of a tiny sample of the debris inside the Unit 2 reactor’s primary containment vessel would start the fuel debris removal phase, which is considered the most challenging part of the decades-long decommissioning process. The Fukushima Daiichi plant suffered severe damage when three reactors were destroyed in the magnitude 9.0 earthquake and tsunami disaster on March 11, 2011.
The work was halted when workers noticed that five 1.5-meter pipes used to maneuver the robot were placed in the wrong order and could not be corrected within their radiation exposure time limit, according to Tokyo Electric Power Company Holdings (TEPCO), which operates the plant.
These pipes were intended for pushing and pulling back out the robot once it entered the vessel. The robot is operated remotely from a safer location once inside.
Equipped with tongs hanging from its tip, this extendable robot can reach up to about 22 meters in order to collect a fragment from the surface of the melted fuel mound. The mission was expected to last two weeks, but TEPCO has not yet announced a new start date.
TEPCO President Tomoaki Kobayakawa emphasized that safety takes precedence over rushing through this process and stated his intention to investigate what caused this pipe setup problem during his visit with reporters in Niigata prefecture.
This sample-return mission marks an important initial step towards decommissioning Fukushima Daiichi over several decades. However, it highlights just how daunting these challenges are as they aim to retrieve less than 3 grams out of an estimated total of 880 tons of fatally radioactive molten fuel.
Experts argue that even though it may seem like a small amount, analyzing this debris sample will provide crucial data for developing future decommissioning methods and necessary technology involving robots.
A better understanding of melted fuel debris is essential for successfully decommissioning all three damaged reactors at Fukushima Daiichi as well as addressing concerns regarding storage plans for this highly radioactive material. Despite criticism claiming that their cleanup target timeframe is unrealistic, both TEPCO and government officials remain committed to completing it within 30-40 years after meltdown occurred.