Immobilization of radioactive wastes in hydrothermal synthetic rock, (II) Hydrothermal synthesis of pollucite.

Yanagisawa, Kazumichi; KANAHARA, Satoshi; Nishioka, Mamoru; Yamasaki, Nakamichi

doi:10.3327/jnst.21.558

Cited by 11 publications

(13 citation statements)

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“…Starting sols were prepared from cesium hydroxide solution (CsOH; Aldrich, Gillingham, Dorset, U.K.), water, aluminum powder (Aldrich), and either ultrafine amorphous SiO 2 powder (OX50, Degussa, Frankfurt, Germany) or a mixture of tetraethyl orthosilicate ((C 2 H 5 O) 4 Si, TEOS; Aldrich) and ethanol. These materials were processed hydrothermally at 220°C for 2 and 24 h with stirring in either of two polytetrafluoroethylene-(PTFE-) lined autoclaves (one manufactured by Berghof GmbH, Eningen, Germany; the other by Baskerville Reactors and Autoclaves, Ltd., Manchester, U.K.).…”

Section: Experimental Methodsmentioning

confidence: 99%

“…Pollucite previously has been considered as a possible material for the immobilization of radioactive 137 Cs (Komarneni and Roy 3 ). Yamasaki and co-workers have produced pollucite for this application from readily available materials, including aluminosilicate rock and silica rock, by hydrothermal synthesis 4 and hydrothermal hot-pressing 5 at temperatures of 200°-300°C.…”

Section: Introductionmentioning

confidence: 99%

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Hydrothermal Synthesis of Pollucite (CsAlSi2O6) Powders

MacLaren

Cirre

Ponton

1999

Journal of the American Ceramic Society

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Pollucite (CsAlSi 2 O 6 ) powders were produced by hydrothermal synthesis from relatively inexpensive precursors. The pollucite powders were comprised of polycrystalline particles with dimensions of hundreds of nanometers consisting of 25-75 nm crystallites. The polycrystalline particles were near stoichiometric composition. The pollucite powders were mixed with a poly(ethylene glycol) binder, pressed into disks, and sintered at temperatures from 1450°t o 1550°C for 10 h. The resulting sintered ceramics had densities >80% of theoretical density and, in the best case, >97% of theoretical density.

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Section: Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hydrothermal Synthesis of Pollucite (CsAlSi2O6) Powders

MacLaren

Cirre

Ponton

1999

Journal of the American Ceramic Society

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“…It has cubic Ia‐ 3 d symmetry and an interconnected framework of (Al,Si)O 4 tetrahedra with randomly distributed Al and Si ions. In addition to other potential applications, pollucite has long been under consideration as a possible host for immobilization of radioactive cesium from spent nuclear fuel . The primary cesium isotope, 137 Cs, has a high β activity due to its short half‐life (30 yr); whereas the other main cesium isotope, 135 Cs, is very long‐lived (half‐life = 2.3 × 10 6 yr).…”

Section: Introductionmentioning

confidence: 99%

“…In addition to other potential applications, [2][3][4] pollucite has long been under consideration as a possible host for immobilization of radioactive cesium from spent nuclear fuel. [5][6][7][8][9] The primary cesium isotope, 137 Cs, has a high b activity due to its short half-life (30 yr); whereas the other main cesium isotope, 135 Cs, is very long-lived (half-life = 2.3 9 10 6 yr). Cesium beta-decays to barium.…”

Section: Introductionmentioning

confidence: 99%

The Synthesis of Ba‐ and Fe‐ Substituted CsAlSi₂O₆ Pollucites

et al. 2013

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Barium‐substituted CsAlSi2O6 pollucites, CsxBa(1−x)/2AlSi2O6, and barium‐ and iron‐substituted pollucites, CsxBa(1−x)/2AlxFe1−xSi2O6 and CsxBa1−xAlxFe1−xSi2O6 were synthesized with 1 ≥ x≥ 0.7 using a hydrothermal synthesis procedure. Rietveld analysis of X‐ray diffraction data confirmed the substitution of Ba for Cs and Fe for Al, respectively. The crystallographic analysis also describes the effects of three different types of pollucite substitutions on the pollucite unit cell: Ba2+ for Cs1+ cation results in little effect on cell dimensions, intermediate concentrations of Ba2+ and Fe3+ substitution result in net minor expansion due to Fe3+ addition, and large Ba and Fe substitutions result in overall framework contraction. Elemental analysis combined with microscopy further supports the phase purity of these new phases. These materials can be used to study the stability of CsAlSi2O6 as a durable ceramic waste form, which could accommodate with time Cs and its decay product, Ba. Furthermore, success in iron substitution for aluminum into the pollucite lattice predicts that redox charge compensation for Cs cation decay is possible.

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“…A high-level radioactive waste form containing silica was produced by the alkali (3-10N NaOH) activation of ?-quartz ( hours. In similar hydrothermal experiments, a mixture of strontium, ?-quartz and NaOH solution resulted in the formation of strontium silicates Yanagisawa et al, 1984, whereas a mixture of cesium, amorphous aluminosilicate with NaOH solution yielded pollucite (CaAlSi 2 O 6 ) . Stone et al, (1979) summarized the pros and cons of alternative waste forms including hot-pressed concretes.…”

Section: Alkali-activated Cementsmentioning

confidence: 99%

Determination of the Rate of Formation of Hydroceramic Waste Forms made with INEEL Calcined Wastes

Scheetz¹,

Olanrewaju²

2001

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iii Executive SummaryA "hydroceramic" nuclear waste form, developed especially to address the immobilization of the reprocessing wastes from the Idaho National Engineering and Environmental Laboratory, has been demonstrated to possess superior chemical and mechanincal properties. Furthermore, the processing requirements of hydroceramic waste forms are simple, less costly and offer greater safety to INEEL personnel than other waste form preparation systems.The objective of this research was two fold. The initial phase of the study was to systematically survey the suitability of readily available pozzolanic additions as raw materials for hydroceramic formulations in order to identify a source material that would be compatible with the established processing requirements for the waste form i.e., no excessive water demand, proper mineralogical composition of the waste form, low leachability, waste loadings greater than 20 weight percent calcine and also readily available to INEEL in large quantities once the pozzolan(s) selection was made. Pozzolanic materials are normally finely divided substances that contain either glassy or crystalline sources of silica that are chemically reactive enough to combine with lime and water at room temperature to form cementitious material. The primary objective of the research program was to establish the final processing parameters for the preparation of hydroceramic waste forms form INEEL wastes i.e., the rate at which hydroceramic is formed, the phases that formed and the optimum temperature needed to minimize leachability.A total of 20 pozzolanic materials were surveyed. These included a number of different fly ash sample, natural and thermally altered clays, reactive aluminas and even finely ground bottle glass. The survey resulted in the selection of a natural, thermally altered clay (metakaolinite) that has found extensive use in the manufacture of blended Portland cement and currently mined in Troy Idaho.A "host" matix formulation was initially developed using Troy metakaolinite and all processing parameters and chemical and mineralogical characterization was conducted on these samples. Once developed, the host matrix was used to subsequently prepare waste forms based on fluorinel and zirconia simulated calcines supplied by INEEL. A waste loading study was conducted in order to determine the maximum loading that could be sustained and still exibit the leaching characteristics and mechanical properties of the laboratory specimens. The "host" matrix samples and the two waste forms were processed at 75, 85, 95, 125, 150, 175 and 200 o C at 100% relative humidity for times often exceeding 500 hours. Two sets of mineralogy were observed for the "host" samples and "waste loaded" samples. The waste loading study optimized the hydroceramic waste form at 30% by weight for both fluorinel and zirconia waste calcines.The hydration rate studies conducted as a function of time and temperature determined that both the "host" matrix formulation and the fluorinel and zirconia waste loaded...

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Immobilization of radioactive wastes in hydrothermal synthetic rock, (II) Hydrothermal synthesis of pollucite.

Cited by 11 publications

References 0 publications

Hydrothermal Synthesis of Pollucite (CsAlSi2O6) Powders

Hydrothermal Synthesis of Pollucite (CsAlSi2O6) Powders

The Synthesis of Ba‐ and Fe‐ Substituted CsAlSi₂O₆ Pollucites

Determination of the Rate of Formation of Hydroceramic Waste Forms made with INEEL Calcined Wastes

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Immobilization of radioactive wastes in hydrothermal synthetic rock, (II) Hydrothermal synthesis of pollucite.

Cited by 11 publications

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Hydrothermal Synthesis of Pollucite (CsAlSi2O6) Powders

Hydrothermal Synthesis of Pollucite (CsAlSi2O6) Powders

The Synthesis of Ba‐ and Fe‐ Substituted CsAlSi2O6 Pollucites

Determination of the Rate of Formation of Hydroceramic Waste Forms made with INEEL Calcined Wastes

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The Synthesis of Ba‐ and Fe‐ Substituted CsAlSi₂O₆ Pollucites