A draft investigation report into the 2011 Fukushima nuclear meltdown, adopted by Japanese nuclear regulators Wednesday, says it has detected dangerously excessive ranges of radioactive contamination at two of the three reactors, including to considerations about decommissioning challenges.
The interim report stated information collected by investigators confirmed that the sealing plugs sitting atop the No. 2 and three reactor containment vessels have been as fatally contaminated as nuclear gasoline particles that had melted and fell to the underside of the reactors following the March 2011 tsunami and earthquake.
The consultants stated the underside of the sealed plug, a triple-layered concrete disc-shaped lid 12 meters (39 ft) in diameter sitting atop the first containment vessel, is coated with excessive ranges of radioactive Cesium 137.
The No. 1 reactor lid was much less contaminated, presumably as a result of the plug was barely knocked misplaced and disfigured as a result of influence of the hydrogen explosion, the report stated.
The consultants measured radiation ranges at a number of areas contained in the three reactor buildings, and examined how radioactive supplies moved and security gear functioned throughout the accident. Additionally they stated venting try at Unit 2 to stop reactor injury by no means labored, and that security measures and gear designs nonetheless must be examined.
The lid contamination doesn’t have an effect on the setting because the containment vessels are enclosed contained in the reactor buildings. The report didn’t give additional particulars about if or how the lid contamination would have an effect on the decommissioning progress.
Nuclear Regulation Fee Chairman Toyoshi Fuketa referred to as the findings “extraordinarily severe” and stated they might make melted gasoline elimination “tougher.” He stated determining easy methods to take away the lids can be a significant problem.
Eradicating an estimated 900 tons of melted gasoline particles from three reactors is a frightening job anticipated to take many years, and officers haven’t been capable of describe precisely when or the way it might finish.
The Fukushima plant was to start out eradicating melted gasoline particles from Unit 2, the primary of three reactors, later this yr forward of the 10th anniversary of the accident. However in December, plant operator Tokyo Electrical Energy Co. and the federal government introduced a delay till 2022. They stated the event of a robotic arm for the particles elimination — a joint mission with Britain — has been delayed as a result of pandemic.
Below the present plan, a remote-controlled robotic arm will likely be inserted from the aspect of the reactor to achieve the molten gasoline blended with melted components and concrete ground of the reactor. Ultimately the lids additionally must be eliminated, however their contamination is a significant setback.
The group of consultants entered areas contained in the three reactors that have been beforehand extremely contaminated and inaccessible after radiation ranges got here down considerably. They’re looking for information and proof earlier than they get misplaced within the cleanup.
Huge radiation from the reactors has induced some 160,000 folks to evacuate from across the plant. Tens of 1000’s are nonetheless unable to return house.