Dealing with the Aftermath of Fukushima Daiichi Nuclear Accident: Decontamination of Radioactive Cesium Enriched Ash

• Published in: Environmental science & technology Vol. 47; no. 8; pp. 3800 - 3806
• Main Authors: Parajuli, Durga, Tanaka, Hisashi, Hakuta, Yukiya, Minami, Kimitaka, Fukuda, Shigeharu, Umeoka, Kuniyoshi, Kamimura, Ryuichi, Hayashi, Yukie, Ouchi, Masatoshi, Kawamoto, Tohru
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 16.04.2013
• Subjects: Adsorbents; Applied sciences; Cesium - isolation & purification; Cesium Radioisotopes; Coal Ash - chemistry; Decontamination - methods; Environmental monitoring; Exact sciences and technology; Fukushima Nuclear Accident; Garbage; Incineration; Leaching; Nuclear accidents & safety; Nuclear power plants; Pollution; Radioactive Pollutants - isolation & purification; Radioactive wastes; Radioactivity; Radioisotopes; Sewage - chemistry; Sludge; Trees - chemistry; Wastes; Water - chemistry; Wood - chemistry; Asia; Japan; Fukushima Japan; Cesium 137; Radioactive pollution; Heat treatment; Waste treatment; Cesium 134; Treatment residue; Radioisotope; Waste disposal; Nuclear accident; Waste management; Decontamination; Incineration; Nuclear power plant; Fission reactor accidents; Ash
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es303467n

Environmental radioactivity, mainly in the Tohoku and Kanto areas, due to the long living radioisotopes of cesium is an obstacle to speedy recovery from the impacts of the Fukushima Daiichi Nuclear Power Plant accident. Although incineration of the contaminated wastes is encouraged, safe disposal of the Cs enriched ash is the big challenge. To address this issue, safe incineration of contaminated wastes while restricting the release of volatile Cs to the atmosphere was studied. Detailed study on effective removal of Cs from ash samples generated from wood bark, household garbage, and municipal sewage sludge was performed. For wood ash and garbage ash, washing only with water at ambient conditions removed radioactivity due to 134Cs and 137Cs, retaining most of the components other than the alkali metals with the residue. However, removing Cs from sludge ash needed acid treatment at high temperature. This difference in Cs solubility is due to the presence of soil particle originated clay minerals in the sludge ash. Because only removing the contaminated vegetation is found to sharply decrease the environmental radioactivity, volume reduction of contaminated biomass by incineration makes great sense. In addition, need for a long-term leachate monitoring system in the landfill can be avoided by washing the ash with water. Once the Cs in solids is extracted to the solution, it can be loaded to Cs selective adsorbents such as Prussian blue and safely stored in a small volume.