Tokyo – A robot that has been operating for months within the wreckage of the tsunami-affected Fukushima Daiichi nuclear plant successfully retrieved a small sample of melted nuclear fuel on Thursday. This development is viewed by plant officials as a significant step towards initiating the cleanup of the vast amounts of melted fuel debris located at the site.
The sample, approximately the size of a grain of rice, was safely secured in a container, culminating the robot’s mission, according to representatives from Tokyo Electric Power Company Holdings, which oversees plant operations. It will be taken to a specialized facility for measurement of its dimensions and weight before undergoing extensive analysis at external laboratories over the coming months.
Akira Ono, the plant’s chief, indicated that this sample would provide crucial data to inform strategies for decommissioning the plant, assist in the development of necessary technologies and robotic systems, and enhance understanding of how the incident unfolded.
Since the catastrophic events of 2011 that resulted in the plant’s devastation and the evacuation of thousands of residents, a considerable amount of the highly radioactive conditions within the facility remains enigmatic.
The recently obtained sample, the first of its kind from inside a reactor, was found to have a lower level of radioactivity than anticipated. Initially, officials had expressed concerns that the radiation levels might render the sample too hazardous for safe handling, even with extensive protective measures in place, and had established a threshold for its extraction. Fortunately, the sample’s radioactivity was well below this limit, raising some skepticism regarding whether the robot succeeded in obtaining the intended nuclear fuel from an area previously indicated to have heightened radiation levels. However, TEPCO officials maintain confidence in the belief that the sample is indeed melted fuel.
The extendable robot, known as Telesco, commenced its mission in August, originally aimed to complete a two-week round trip, although previous efforts had been postponed since 2021. The mission encountered interruptions twice, first due to an assembly error that took nearly three weeks to correct, followed by a malfunction with one of its cameras.
On October 30, the robot successfully collected a sample weighing less than 3 grams from a surface located on a mound of melted fuel debris at the base of the Unit 2 reactor’s primary containment vessel, according to TEPCO. Three days later, the robot re-entered its enclosed container as hazmat-suited workers carefully extracted it from the hazardous environment.
On Thursday, the debris, which had recorded a radioactivity level significantly lower than the stipulated safety regulations earlier in the week, was placed into a secure container for removal from the compartment. The successful retrieval of this sample marks a historic moment as it is the first instance of melted fuel being extracted from within the containment vessel.
The Fukushima Daiichi plant experienced failures in its cooling systems during the 2011 earthquake and subsequent tsunami, leading to meltdowns in three of its reactors. Currently, an estimated 880 tons of dangerously radioactive melted fuel remains within the reactors.
Both the government and TEPCO have set an ambitious target of 30 to 40 years to complete the cleanup process by 2051; however, experts have criticized this timeline as overly optimistic, suggesting that it could potentially take a century or more. No concrete plans have yet been finalized regarding the full removal and ultimate disposal of the melted fuel debris.