Behavior of cesium in municipal solid waste incineration

Oshita, Kazuyuki; Aoki, Hiroshi; Fukutani, Satoshi; Shiota, Kenji; Fujimori, Takashi; Takaoka, Masaki

doi:10.1016/j.jenvrad.2015.01.019

Cited by 27 publications

(18 citation statements)

References 12 publications

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“…Although in a different environment and different circumstances, the release of 137 Cs from incineration of MSW contaminated by radioactivity from the Fukushima nuclear accident, in Japan, was also investigated and reported (Oshita et al, 2015). The severity of the radiological impact from these accidents may vary from minor (e.g., incineration of radioactive residue from treatment of a cancer patient who has returned home), to very serious, such as the volatilization of a source of cesium ( 137 Cs) in the Algeciras steelworks in 1997, which gave rise to a radioactive cloud detected in France (Estevan, 2004).…”

Section: Incineration Of Municipal Solid Waste and Possible Radiologimentioning

confidence: 99%

Can the incineration of Municipal Solid Waste pose occupational and environmental radiation hazards?

Carvalho

2017

IJOOES

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An evaluation of the incineration process of municipal solid waste is made for identifying potential radiation hazards. Sources of radiation considered are the radioactive materials wrongly eliminated into municipal waste (e.g., industrial and medical waste containing radioactive sources, such as cesium-137 and technetium-99m) and also radionuclides of natural origin (e.g., radium-226, polonium-210) contained in common materials disposed as domestic waste. Through burning, radionuclides from both origins may be released as gases and radioactive particles into the atmosphere and build up in the facility and in the environment nearby. Results from model calculations indicated that naturally-occurring radionuclides released into the atmosphere likely originate a small enhancement to the natural radiation background. However, in the case of man-made radioactive sources mixed with the municipal solid waste the radioactive emissions may attain and eventually exceed the radiation dose limit for members of the public. These results support the recommendation that for natural radionuclides present in incinerated waste a careful evaluation of the risk of exposure to ionizing radiation, actually in accord to the European Directive 2013/59/EURATOM establishing the basic safety standards for radiation protection, must be performed and model calculations validated with radioactivity measurements. Regarding the potential release of radionuclides from man-made radioactive sources it is recommended the installation of portals equipped with radiation detectors to check municipal solid waste on admission in the facilities and prevent such radiological accident.

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Section: Incineration Of Municipal Solid Waste and Possible Radiologimentioning

confidence: 99%

Can the incineration of Municipal Solid Waste pose occupational and environmental radiation hazards?

Carvalho

2017

IJOOES

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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%

“…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. The percentages of water-soluble fractions of r-Cs of MSWI-FA were all in the range of approximately 60–90%, 9,13−16 while those of the BA were less than several percentages.…”

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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“…The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident triggered by the massive earthquake and tsunami on March 11, 2011, resulted in a substantial release of radioactive nuclides, contaminating the disaster waste, soil, crops and trees around the area of the FDNPP. − Among these radionuclides, the radioactive cesium (Cs) isotopes 134 Cs ( T 1/2 = 2.065 y) and 137 Cs ( T 1/2 = 30.08 y) are of primary concern because of their long half-lives. , To reduce the radiation level in the surrounding area, decontamination operations, in which the contaminated solid wastes are collected and stored in a designated storage, have been occurring for more than four years until present day. Following these decontamination operations, incineration is one of the recommended approaches for the safe handling of such large amounts of Cs-contaminated solid wastes.…”

Section: Introductionmentioning

confidence: 99%

Vaporization Mechanisms of Water-Insoluble Cs in Ash During Thermal Treatment with Calcium Chloride Addition

Jiao

Iwata

Kinoshita

et al. 2016

Environ. Sci. Technol.

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The vaporization mechanisms of water-insoluble Cs in raw ash and Cs-doped ash during thermal treatment with CaCl addition was systematically examined in a lab-scale electrical heating furnace over a temperature range of 500-1500 °C. The results indicate that the water-insoluble Cs in the ash was associated with aluminosilicate as pollucite. Addition of 10% CaCl caused the maximum vaporization ratio of Cs in the raw ash to reach approximately 80% at temperatures higher than 1200 °C, whereas approximately 95% of Cs was vaporized at temperatures higher than 1300 °C when 30% CaCl was added. The formation of an intermediate compound, CsCaCl, through the chemical reaction of Cs with CaCl was responsible for Cs vaporization by means of the subsequent decomposition of this intermediate upon the increase in temperature. The indirect chlorination of Cs by the gaseous chlorine released from the decomposition of CaCl was insignificant. A high CaCl content in the resulting annealed products with 30% CaCl addition delayed the decomposition of CsCaCl and thus lowered the Cs vaporization ratio compared to that with 10% CaCl addition at 900-1250 °C. Thermal treatment with CaCl addition is a proposed method to remove Cs from Cs-contaminated incineration ash.

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Behavior of cesium in municipal solid waste incineration

Cited by 27 publications

References 12 publications

Can the incineration of Municipal Solid Waste pose occupational and environmental radiation hazards?

Can the incineration of Municipal Solid Waste pose occupational and environmental radiation hazards?

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

Vaporization Mechanisms of Water-Insoluble Cs in Ash During Thermal Treatment with Calcium Chloride Addition

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