A chemical basis for the partitioning of radionuclides in incinerator operation

Burger, L.L.

doi:10.2172/10120070

Cited by 7 publications

(6 citation statements)

References 5 publications

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“… a Calculated by subtraction. b Atomic absorption spectrometry. c Inductively coupled plasma-atomic emission spectroscopy (ICP-AES). d Alkali fusion and ICP-AES. e Ashing, alkali fusion, hydrofluoric acid treatment, and gravimetry. f Inductively coupled plasma mass spectrometry (ICP-MS). g From the average of MSW1 to MSW3. h Ion chromatography after ignition in an oxygen-enriched atmosphere, i (C + H + N + O + S + Cl). j Mean value of ref (61 mg kg –1 , d.b.) and ref (150 mg kg –1 , d.b.…”

Section: Calculation Methodsmentioning

confidence: 99%

“…To further understand the behavior of Cs in incinerators and to identify the chemical forms of Cs species in the ash, theoretical approaches such as thermodynamic equilibrium calculation would be appropriate to complement the lacking information. Thermodynamic equilibrium calculations have been employed to examine the fate of alkali species in incinerators − as well as to predict the chemical forms of radioactive species in thermal treatments for radioactive wastes. , Although complete representation of all processes occurring in incineration facilities remains a challenge for any theoretical approach, thermodynamic equilibrium calculation has an advantage in that it can evaluate the possible chemical changes in a system that includes many components, such as in an MSW incinerator or an SS incinerator, and therefore it fits in evaluating the behavior of r-Cs in incineration plants.…”

Section: Introductionmentioning

confidence: 99%

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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: Calculation Methodsmentioning

confidence: 99%

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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“…Cesium salts are relatively volatile, and significant quantities of cesium may partition to the off-gas during high-temperature thermal processing (Stockdale et al, 1994;Burger, 1995).…”

Section: Overviewmentioning

confidence: 99%

Evaluation of interim and final waste forms for the newly generated liquid low-level waste flowsheet

Abotsi

Bostick²,

Beck

1996

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“…These relative values for radioisotopes in the sludge material are consistent with the fact that cesium salts are predominantly soluble in wastewater (and thus cesium is only incidentally present in partially dayatered sludge), whereas strontium behaves chemically similar to calcium, the predominant component in the sludge solids (vide infra). However, the presence of small amounts of radiocesium in the waste does present a potential challenge for high-temperature waste processing (calcination or melting), due to its relative volatility Gibson et al, 1994;Burger, 1995).…”

Section: Authentic Water Softening Sludgementioning

confidence: 99%