Evaluation of physicochemical properties of radioactive cesium in municipal solid waste incineration fly ash by particle size classification and leaching tests

Fujii, Kengo; Ochi, Kotaro; Ohbuchi, Atsushi; Koike, Yuya

doi:10.1016/j.jenvman.2018.03.028

Cited by 38 publications

(31 citation statements)

References 13 publications

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“…Current knowledge on the behavior of r-Cs or stable Cs in MSWI and SSI is as follows: more than half of the r-Cs 9 and stable Cs 22 in MSW were distributed to fly ash (MSWI-FA) in stoker incineration plants. The chemical form of Cs in MSWI-FA was identified as mostly chlorides 9,10,12,16 or at least water-soluble forms. 13−16 According to the analyses of the residues of co-incineration of MSW and Cs 2 CO 3 reagent, 11,12 Cs in the MSW bottom ash (MSWI-BA) was mostly glassy materials or metal sulfides or crystalline aluminosilicates such as pollucite, except for the unchanged reagents.…”

Section: Introductionmentioning

confidence: 99%

Understanding the Behavior of Radioactive Cesium during the Incineration of Contaminated Municipal Solid Waste and Sewage Sludge by Thermodynamic Equilibrium Calculation

2018

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Following the nuclear accident at the Fukushima Daiichi Nuclear Power Plant in 2011, even the municipal solid waste (MSW) and sewage sludge (SS) in northeastern Japan became contaminated by radioactive nuclides such as 137 Cs and 134 Cs. To understand the state of radioactive cesium (r-Cs) in the incineration residues of the municipal wastes, research groups studied the concentration and the chemical form of r-Cs in the residues, as well as its water-leaching behavior. In the present study, we conducted thermodynamic equilibrium calculations to estimate the possible chemical forms of r-Cs in the incineration residues. Thermodynamic data for cesium oxides and aluminosilicates were collected and compiled into a new database to perform equilibrium calculations for systems that include Cs. The calculation results suggested that Cs (radiocesium and stable cesium) in municipal solid waste was transformed into gaseous CsCl or crystalline aluminosilicate at incineration temperatures and, when a molten aluminosilicate phase (i.e., slag phase) was generated, a proportion of the Cs species was dissolved into the slag phase. In the case of sewage sludge, Cs was calculated to be transformed mostly into crystalline aluminosilicate at incineration temperatures, whereas by analogy with the behaviors of Na and K, Ca,Cs-phosphate double salts were also potential incineration products. These results could account for the high leaching rates of r-Cs from the MSW incineration fly ash and the low leaching rates from the MSW incineration bottom ash and SS incineration fly ash reported in earlier studies. In the case of dewatered SS that included a large amount of slaked lime as a flocculant, it was exceptionally difficult for the calculation to represent the fate of Cs, and we needed to include the contribution of silica sand in a fluidized-bed combustor in the equilibrium calculation to represent the low leaching rates of alkali species from the dewatered SS fly ash. From the results of the thermodynamic equilibrium calculations and also from the calculated standard Gibbs energy of cesium aluminosilicate formation/decomposition reactions, the effects of waste composition and incineration temperature on the fate of Cs were examined: High incineration temperature and large amounts of Ca and Cl in the waste composition increased the fraction of gaseous CsCl in the furnace and thus resulted in the high distribution ratios of Cs in the fly ash of MSW and the high leaching rates of Cs from the fly ash.

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Section: Introductionmentioning

confidence: 99%

Understanding the Behavior of Radioactive Cesium during the Incineration of Contaminated Municipal Solid Waste and Sewage Sludge by Thermodynamic Equilibrium Calculation

2018

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“…The reaction equation can be used to make this procedure more visible. Under these assumptions, the main procedure can be described using eqn (1)- (9) and as shown in Fig. 8.…”

Section: Mechanism Illustrationmentioning

confidence: 99%

“…Due to the low cost 7 and excellent ion-exchange capability, clay is recommended as a backll material to hinder radionuclide migration in the disposal of high-level radionuclide waste (HLRW). 8 Except for the retention of radionuclides, 9,10 it can uptake water and bear various irradiations such as g/b-rays for radionuclide decay during its service duration. 11,12 This irradiation can lead to H 2 O radiolysis and destroy the structure of the clay matrix.…”

Section: Introductionmentioning

confidence: 99%

“…23 Nevertheless, having a clear understanding of the mechanism of radiation damage within clay is meaningful for the disposal of HLRW, 23 and it is also essential in the evaluation of the effect of nuclear accidents on the environment (e.g., Fukushima Daiichi nuclear power plant accident). 9 The research in this eld is essential for the sustainable development of nuclear power.…”

Section: Introductionmentioning

confidence: 99%

“…are the probable reactions originally induced by g-ray irradiation.Si-O-Si^/^Sic + $O-Si^(1) Si-OH /^Sic + HOc (Si-O-Mg-O-Si^/^Sic + $O-Mg-O-Si^(3) Si-O-Mg-O-Si^/^Si-Oc + $Mg-O-Si^(4) / Hc + HOc(5)Eqn (6)-(9) are the probable reactions between the radiolysis products.^Sic + HOc /^Si-OH (SEM images of the surfaces of (a) pristine, (b) 200 kGy-irradiated, and (c) 1000 kGy-irradiated samples. This journal is © The Royal Society of Chemistry 2019 RSC Adv., 2019, 9, 6199-6210 | 6207 Paper RSC Advances Open Access Article.…”

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Intensive evaluation of radiation stability of phlogopite single crystals under high doses of γ-ray irradiation

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Quantitative phase analysis of fly ash of municipal solid waste by X-ray powder diffractometry/Rietveld refinement

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Nakamura

2019

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Evaluation of physicochemical properties of radioactive cesium in municipal solid waste incineration fly ash by particle size classification and leaching tests

Cited by 38 publications

References 13 publications

Understanding the Behavior of Radioactive Cesium during the Incineration of Contaminated Municipal Solid Waste and Sewage Sludge by Thermodynamic Equilibrium Calculation

Understanding the Behavior of Radioactive Cesium during the Incineration of Contaminated Municipal Solid Waste and Sewage Sludge by Thermodynamic Equilibrium Calculation

Intensive evaluation of radiation stability of phlogopite single crystals under high doses of γ-ray irradiation

Quantitative phase analysis of fly ash of municipal solid waste by X-ray powder diffractometry/Rietveld refinement

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