Hydrothermal crystallization of a radioactive waste storage glass

Savage, David; Robbins, Jane E.; Merriman, R. J.

doi:10.1180/minmag.1985.049.351.06

Cited by 11 publications

(7 citation statements)

References 22 publications

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“…Stillwellite is of interest because of its ferroelectric, non-linear optical and piezoelectric properties [42,43]. This phase was also reported as a product formed during nuclear waste glass dissolution experiment under severe conditions [44]. For RE = Gd, a distinct phase exhibiting the same stoichiometry as stillwellite (GdBSiO5) and belonging to the monoclinic crystal system was observed, identical to the one reported for small REs (Nd-Dy) within the REBGeO5 (borogermanate) family [35,45].…”

Section: Crystalline Phasesmentioning

confidence: 99%

Exploration of glass domain in the SiO2-B2O3-La2O3 system

Trégouët

Caurant

Majérus

et al. 2017

Journal of Non-Crystalline Solids

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The existence of a relatively wide glass domain has been put in evidence in the SiO2-B2O3-La2O3 ternary system, using a melt-quenching method. This domain extends from a region surrounding the lanthanum metaborate (LaB3O6) composition in the B2O3-La2O3 binary system to ternary compositions bearing up to 39 mol% SiO2. Outside this domain, phase separation phenomena and/or crystallization of La-rich borate (LaBO3) and borosilicate (La3Si2BO10) phases are observed during quenching. The evolution of glass transition temperature (Tg) with composition in the glassy domain has been studied and discussed according to structural changes put in evidence by 11 B MAS NMR. Moreover, the evolution of the thermal stability of a series of glasses derived from a lanthanum metaborate glass by substituting B2O3 by increasing amount of SiO2 (up to 36 mol% SiO2) was studied by DTA and thermal treatments followed by characterization by XRD and Raman spectroscopy. In spite of silica-enrichment along the glass series, the first phases crystallizing during heating were always lanthanum borates (LaB3O6, LaBO3) according the following sequence when SiO2 content increases:

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Section: Crystalline Phasesmentioning

confidence: 99%

Exploration of glass domain in the SiO2-B2O3-La2O3 system

Trégouët

Caurant

Majérus

et al. 2017

Journal of Non-Crystalline Solids

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“…Zektzerite crystals are a potential host for 93 Zr and U [109]. Zektzerite crystals are also a potential host for 126 Sn because Sn is predominantly in the +4 oxidation state and coordinated to six oxygens in borosilicate HLW glasses [115] (as is Zr in borosilicate HLW glasses and zektzerite [116]) and has a similar ionic radius to Zr 4+ [92], demonstrated by LiNaSnSi 6 O 15 being isostructural with zektzerite [113].…”

Section: Linazrsi 6 O 15 (Zektzerite)mentioning

confidence: 99%

“…Zektzerite crystals have been reported to form in the altered surface layers of a borosilicate HLW glass during high temperature aqueous durability testing [109].…”

Section: Linazrsi 6 O 15 (Zektzerite)mentioning

confidence: 99%

Crystallisation of a simulated borosilicate high-level waste glass produced on a full-scale vitrification line

Rose

Woodward

Ojovan

et al. 2011

Journal of Non-Crystalline Solids

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A simulated (inactive) borosilicate high-level waste (HLW) glass was produced on a full-scale vitrification line with composition simulating vitrified oxide fuel (UO 2 ) reprocessing waste. As-cast samples were compositionally homogeneous (Type I microstructure) and/or compositionally inhomogeneous displaying compositional 'banding' and frequently containing 'reprecipitated calcine' (Type II microstructure).Crystal phases identified in as-cast samples were: tetragonal RuO 2 , cubic Pd-Te alloy, cubic (Cr,Fe,Ni,Ru) Sn and U). Cracking in samples was attributed to thermal expansion mismatch between the borosilicate HLW glass matrix and RuO 2 , cristobalite (both α and β), (Na,Sr,Nd,La)MoO 4 and zektzerite on cooling. There was also a contribution from the cristobalite α-β phase transition.

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“…They were heated in an autoclave at 200°C with a vapor pressure of about 1.54 MPa. Since the maximum temperatures is estimated to be 150 to 200°C in deep geological repositories in the first few hundred years after disposal (Savage et al, 1985), the temperature of 200°C was chosen, which temperature accelerated alteration process of glasses. The run duration is 60 days at the longest.…”

Section: Hydrothermal Treatmentmentioning

confidence: 99%

“…In nature, pollucite is only one aluminosilicate containing cesium (Keith et al, 1983). Savage et al (1985) demonstrates that a borosilicate waste glass breaks down rapidly in the presence of an aqueous fluid at high temperatures. The breakdown of waste glass may result in release of waste elements.…”

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confidence: 99%

Implications of Analcime Hydrothermally Formed from Na‐alumino‐borosilicate Glasses Containing Cs and Sr for the Stability of High‐level Radioactive Waste Form

et al. 2003

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Abstract:In order to know the behaviors of radioactive elements such as cesium and strontium during a hydrothermal alteration of borosilicate glass of radioactive waste, some alumino-borosilicate glasses belonging to the systems Na 2 O-Al 2 O 3 -B 2 O 3 -SiO 2 -SrO, Na 2 O-Al 2 O 3 -B 2 O 3 -SiO 2 -Cs 2 O and Na 2 O-Al 2 O 3 -B 2 O 3 -SiO 2 -SrO-Cs 2 O have been treated hydrothermally at 200°C under a vapor pressure of 1.54 MPa. The result shows that all glasses are changed into crystalline phases with running time up to 60 days, and that analcime-type zeolite is formed as a major product. The formed zeolite is shown to contain cesium and/or strontium. Considering the fact that natural zeolite occurs in wide physicochemical conditions including hydrothermal one, the analcime-type zeolite is expected to fix stably the radioactive elements in the disposal site. Since aluminum is necessary for the formation of the analcime-type zeolite, the waste glass should have aluminum as one of major components.Keywords: radioactive waste, borosilicate glass, alteration, analcime-type zeolite, cesium, strontium Experimental Starting materialsAluminum is added as a major component to the sodium-borosilicate glass compositions examined before by Sohn et al. (2001). Since lithium is difficult to analyze and its content in actual radioactive waste glass is low, lithium was excluded in the present study.Before the main experiment, a preliminary experiment was carried out to examine the influence of addition of aluminum to glass component. The glass compositions of the preliminary experiment are based on the radioactive waste glass proposed in Japan (IAEA, 1979) except minor components. Since analcime-type zeolite was formed as a major product in the preliminary experiment, the chemical formula of analcime-type zeolite was selected as the chemical compositions of the starting glasses: Si/(Al+B) = 2 and (Al+B)/(Na+Cs+2Sr) = 1 in the main experiment.Each starting material tested in the preliminary and main experiments belongs to one of systems Na 2 OAl 2 O 3 -B 2 O 3 -SiO 2 -SrO (System NABS-Sr), Na 2 OAl 2 O 3 -B 2 O 3 -SiO 2 -Cs 2 O (System NABS-Cs) and Na 2 OAl 2 O 3 -B 2 O 3 -SiO 2 -SrO-Cs 2 O (System NABS-SrCs). Each glass was prepared by the following procedure: 1) reagent-grade B 2 O 3 , Al 2 O 3 and SiO 2 were dried at about 1200°C for over 20 minutes; 2) reagent-grade Na 2 CO 3 , Cs 2 CO 3 and SrCO 3 were dried, and decarbonated at about 850°C for over 30 minutes; 3) these reagents were weighted in appropriate proportions in accordance with each starting composition, and mixed for 20 minutes; 4) each oxide mixture was melted in a platinum crucible at about 1200°C for about one hour; 5) after melting, the melt was quenched; 6) the obtained glass was crushed, and ground to grain size of about 50 µm; and 7) this melting and grinding process was carried out two times in total.In each system, three different glass compositions were prepared (Table 1): one for the preliminary experiment, the other two for the main experiment as s...

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Hydrothermal crystallization of a radioactive waste storage glass

Cited by 11 publications

References 22 publications

Exploration of glass domain in the SiO2-B2O3-La2O3 system

Exploration of glass domain in the SiO2-B2O3-La2O3 system

Crystallisation of a simulated borosilicate high-level waste glass produced on a full-scale vitrification line

Implications of Analcime Hydrothermally Formed from Na‐alumino‐borosilicate Glasses Containing Cs and Sr for the Stability of High‐level Radioactive Waste Form

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