KYOTO--Researchers say they have developed a new technology for efficiently isolating and removing fine particles that contain radioactive cesium from farm soil.
KYOTO--Researchers say they have developed a new technology for efficiently isolating and removing fine particles that contain radioactive cesium from farm soil.
The team of scientists from Kyoto University and other institutions said Dec. 13 that during a demonstration in Fukushima Prefecture their method cut the levels of radioactive substances by 90 percent in farm soil.
Until now, that had been considered a daunting challenge.
Most radioactive cesium that exists in soil is strongly bonded with fine clay particles with diameters of 0.005 millimeter or less. Technology to efficiently separate radioactive cesium from clayey farmland soil and fine-particle incinerator ash has yet to be developed.
Haruhiko Toyohara, a Kyoto University associate professor of marine biological function, and co-workers developed equipment that washes soil with "nano-bubble water," which contains extremely small bubbles, and uses a vortex to separate the particles that stir up in the water. They successfully separated soil components with diameters of up to 0.075 mm into fine clay particles and larger particles.
The fine clay particles can be solidified with an agent to be disposed of as radioactive waste, whereas the other soil components can be reused in coastal levees and other objects, the researchers said.
The team said its equipment, worth between 350 million yen ($3.38 million) and 400 million yen, can treat 10 tons of contaminated soil per hour.
The researchers said they removed 92 percent of the initial radioactive cesium content of 13,800 becquerels per kilogram of farmland surface soil during the demonstration test in Fukushima Prefecture, with the solid radioactive waste having only 15 percent of the initial bulk.