Environmental Radionuclide Science & Engineering

Associate Professor

  • FUJIKAWA, Yoko e-mail: fujikawa<atmark>

Assistant Professors

  • KUBOTA, Takumi e-mail: t-kubota<atmark>

* replace <atmark> with @rri.kyoto-u.ac.jp
Investigation of the behavior and remediation technology of radioactive and non-radioactive pollutants in the environment

We have investigated the behavior of radioactive and non-radioactive pollutants, as well as environmental remediation technologies, with special focus on the geo-hydrological environment. Our research activities encompass the laboratory test to clarify the distribution of pollutants among geological media, water, and living plants etc., development of analytical methods to determine the concentration and chemical speciation of pollutants as well as the application of the developed method, field research of distribution radioactive Cs, U and Pu isotopes, development of decontamination technologies for soil and water, contaminant transport modeling, and safety assessment of radioactive waste disposal.

Toward the safe disposal of nuclear wastes and municipal solid wastes contaminated with radioactive cesium from the Fukushima accident

Wastes are inevitable products of anthropogenic activity. Once generated, wastes have to be disposed after appropriate pretreatment, but the siting of waste landfill has always been a big challenge. This is especially true for wastes containing radioactive materials. To contribute to the safe disposal of radioactive wastes, we have conducted basic study on the transport and distribution of important radionuclides originating from nuclear wastes (e.g., I-129, Se-79, Cs-135, Co-60, uranium isotopes and transuranium elements) in the geosphere.

The Fukushima Daiichi Nuclear Power Plant accident in 2011 has created an entirely new dimension in environmental problems: radioactive cesium (rad-Cs hereafter) contamination of the general environment. The contamination has lead to the generation of huge amount of removed soil from clean-up work and municipal solid wastes, both containing rad-Cs. Our most recent research activities are related to the volume reduction of such wastes. In particular, we have investigated a technique that washes the waste (rad-Cs > 8,000 Bq/kg, so-called designated waste) with aqueous solvents, and removes the extracted rad-Cs using hexacyanoferrate coprecipitation procedure. We have conducted on-site tests to prove the effectiveness of the technique (images of the test are shown below). We have now launched a new field research to investigate the migration of rad-Cs in the underground environment.

Groundwater survey in the GAB, Australia