A robot that spent months exploring the devastated ruins of the Fukushima Daiichi nuclear power plant, which was impacted by a tsunami in Japan, successfully retrieved a small sample of melted nuclear fuel on Thursday. This marks a significant step forward in the process of removing the estimated hundreds of tons of melted nuclear material, according to officials at the plant.
Managed by Tokyo Electric Power Company Holdings, the retrieved sample, about the size of a grain of rice, was placed into a secure container as the robot’s mission concluded. The sample will now be moved to a glove box for size and weight measurements before being sent to an external laboratory for comprehensive analysis over the coming months.
Director Akira Ono emphasized that this undertaking will yield vital information for planning decommissioning efforts, advancing technology and robotics, and gaining insights into the accident’s aftermath.
Despite numerous investigations following the catastrophic 2011 disaster that led to the plant’s destruction and the evacuation of thousands, much about the highly radioactive site remains unknown.
The initial samples retrieved from the reactor were found to be notably less radioactive than anticipated. Officials had imposed strict limits on the amount of radioactivity that could be extracted, out of concern that it might be too hazardous for testing even with extensive protective measures. Fortunately, the sample was significantly below those limits.
This outcome has sparked questions regarding whether the robots successfully extracted the nuclear fuel from areas where previous analysis indicated much higher levels of radioactive contamination. Nevertheless, TEPCO officials remain optimistic, asserting that the samples obtained are indeed from the molten fuel.
The telescoping robot, named Telesco, embarked on its inaugural mission in August, which was initially scheduled to take two weeks before being postponed from 2021. However, progress was hindered twice: first by an assembly error that delayed operations for almost three weeks, and secondly by a camera malfunction.
TEPCO reported on October 30 that they obtained a sample weighing less than 0.01 ounces from the surface of a mass of melted fuel debris located within the primary containment vessel of Unit 2.
Shortly afterward, a protective-clad worker carefully retrieved the robot and returned it to its sealed container.
On Thursday, the gravel, which had previously been assessed for radioactivity and found to be well within environmental and health safety limits, was safely stored for transportation outside the site.
The retrieval of this sample signifies the first successful recovery of melted fuel from within the containment structure.
In 2011, the Fukushima Daiichi suffered a loss of critical cooling systems due to an earthquake and tsunami, leading to meltdowns in three reactors. It is estimated that around 880 tons of dangerously radioactive fuel are still contained within the plant.
The Japanese government and TEPCO have set a timeline of 30-40 years to achieve full cleanup by 2051; however, experts suggest that this timeframe may be overly ambitious and needs to be reevaluated. Some believe that the entire process may extend beyond a century.
Currently, no definite plans have been established for the complete removal of the fuel debris or its ultimate disposal.
