Cesium distribution and phases in proxy experiments on the incineration of radioactively contaminated waste from the Fukushima area

• Published in: Journal of environmental radioactivity 2014-10, Vol.136, p.76-84
• Main Authors: Saffarzadeh, Amirhomayoun, Shimaoka, Takayuki, Kakuta, Yoshitada, Kawano, Takashi
• Format: Article
• Language: English
• Subjects: Applied sciences; Ashes; Categories; Cesium - analysis; Cesium compounds; Cesium Radioisotopes - analysis; Coal Ash - analysis; Combustion; Contamination; Disaster waste; Exact sciences and technology; Fukushima Nuclear Accident; Incineration; Nuclear accidents; Other wastes and particular components of wastes; Particle Size; Partitioning; Pollution; Radioactive Waste - analysis; Radioactivity; Spectrometry, X-Ray Emission; Synthesized bottom ash; Tohoku earthquake; Wastes
• ISSN: 0265-931X; 1879-1700
• DOI: 10.1016/j.jenvrad.2014.05.009

After the March 11, 2011 Tohoku earthquake and Fukushima I Nuclear Power Plant accident, incineration was initially adopted as an effective technique for the treatment of post-disaster wastes. Accordingly, considerable amounts of radioactively contaminated residues were immediately generated through incineration. The level of radioactivity associated with radiocesium in the incineration ash residues (bottom ash and fly ash) became significantly high (several thousand to 100,000 Bq/kg) as a result of this treatment. In order to understand the modes of occurrence of radiocesium, bottom ash products were synthesized through combusting of refuse-derived fuel (RDF) with stable Cs salts in a pilot incinerator. Microscopic and microanalytical (SEM-EDX) techniques were applied and the following Cs categories were identified: low and high concentrations in the matrix glass, low-level partitioning into some newly-formed silicate minerals, partitioning into metal-sulfide compounds, and occurring in newly-formed Cs-rich minerals. These categories that are essentially silicate-bound are the most dominant forms in large and medium size bottom ash particles. It is expected that these achievements provide solutions to the immobilization of radiocesium in the incineration ash products contaminated by Fukushima nuclear accident. •Behavior of cesium in the waste incineration residues was investigated.•Bottom ash products were synthesized through combusting of stable cesium salts and RDF.•Microscopic and microanalytical techniques were applied.•Cesium distribution and phases were identified in bottom ash products.•Cesium is entrapped in silicate glass, minerals and metal-sulfide phases of bottom ash.