Sol-Gel Processing of Silica Nuclear Waste Glasses

Deptula, A.; Miłkowska, Magdalena; Łada, W.; Olczak, Teresa; Wawszczak, D.; Smoliński, Tomasz; Zaza, F.; Brykala, Marcin; Chmielewski, A.G.; Goretta, K. C.

doi:10.4236/njgc.2011.13015

Cited by 6 publications

(3 citation statements)

References 23 publications

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“…The porous structure of the aerogel is used as a volume host. This method would make it possible to confine nuclear waste in the porosity [19,33,34]. The important characteristic is the very high chemical durability of the silica matrix that would protect nuclear waste from corrosion by water.…”

Section: 5) Multi Component Glassesmentioning

confidence: 99%

Porous glasses from aerogels: from organic liquid to mineral materials

Woignier

Duffours²,

Primera

2022

J Sol-Gel Sci Technol

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According to an easy sintering stage, composite aerogels are alternative ways to synthesize silica glass at temperatures ranging from 900 to 1200 °C, close to half the temperatures used for the glass melting process. The heat treatment is tailored to obtain fully densified or porous glasses. The kinetics of dimensional shrinkage is characterized during the sintering mechanism, and we confirmed that the viscous flow-sintering model also applies to composite aerogels. Porous glasses with a broad range of porosity and physical properties (mechanical strength, elasticity modulus, permeability) have been synthesized. The open pore structure is used to synthesize glass ceramics.

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Section: 5) Multi Component Glassesmentioning

confidence: 99%

Porous glasses from aerogels: from organic liquid to mineral materials

Woignier

Duffours²,

Primera

2022

J Sol-Gel Sci Technol

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“…Drying may require temperatures nearer 100 °C, and additional compaction may be desirable. Sol-gel processes tend to be highly tolerant of additives; for example, incorporation of salt and oxide surrogates into durable waste forms has been demonstrated in proof-of-concept experiments [Deptula 2011, Zelinski 1998]. A significant drawback, however, is the need to collect and manage hydrolysis byproducts such as ethanol or methanol.…”

Section: Low Temperature Sol-gel Processingmentioning

confidence: 99%

Candidate Low-Temperature Glass Waste Forms for Technetium-99 Recovered from Hanford Effluent Management Facility Evaporator Concentrate

Ding

Tang

Rim

et al. 2017

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Alternative treatment and disposition options may exist for technetium-99 (99 Tc) in secondary liquid waste from the Hanford Direct-Feed Low-Activity Waste (DFLAW) process. One approach includes development of an alternate glass waste form that is suitable for on-site disposition of technetium, including salts and other species recovered by ion exchange or precipitation from the EMF evaporator concentrate. By recovering the Tc content from the stream, and not recycling the treated concentrate, the DFLAW process can potentially be operated in a more efficient manner that lowers the cost to the Department of Energy. This report provides a survey of candidate glass formulations and glass-making processes that can potentially incorporate technetium at temperatures <700 °C to avoid volatilization. Three candidate technetium feed streams are considered: (1) dilute sodium pertechnetate loaded on a non-elutable ion exchange resin; (2) dilute sodium-bearing aqueous eluent from ion exchange recovery of pertechnetate, or (3) technetium(IV) oxide precipitate containing Sn and Cr solids in an aqueous slurry. From the technical literature, promising candidate glasses are identified based on their processing temperatures and chemical durability data. The suitability and technical risk of three low-temperature glass processing routes (vitrification, encapsulation by sintering into a glass composite material, and sol-gel chemical condensation) for the three waste streams was assessed, based on available low-temperature glass data. For a subset of candidate glasses, their long-term thermodynamic behavior with exposure to water and oxygen was modeled using Geochemist's Workbench, with and without addition of reducing stannous ion.

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“…The properties of silica glasses, including good durability and mechanical strength and the ability to incorporate large concentrations of dopants, make them ideal candidates as matrices for the storage of nuclear waste. The main disadvantage of silica glasses for this kind of use is their high processing temperature of ∼2,000 ∘ C. However, it has been shown that the sol-gel process is an appropriate low temperature process to obtain glasses at around 1,000 ∘ C, not by melting but by sintering of a nanoporous amorphous silica gel [13][14][15][16][17][18][19][20]. In this paper, we compare different nanoporous silica networks as possible host matrices for actinides and assess the feasibility of fixing actinides in silica glass.…”

Section: Introductionmentioning

confidence: 99%

Nanoporous Glasses for Nuclear Waste Containment

Woignier

Primera²,

Jér

et al. 2016

Journal of Nanomaterials

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Research is in progress to incorporate nuclear waste in new matrices with high structural stability, resistance to thermal shock, and high chemical durability. Interactions with water are important for materials used as a containment matrix for the radio nuclides. It is indispensable to improve their chemical durability to limit the possible release of radioactive chemical species, if the glass structure is attacked by corrosion. By associating high structural stability and high chemical durability, silica glass optimizes the properties of a suitable host matrix. According to an easy sintering stage, nanoporous glasses such as xerogels, aerogels, and composite gels are alternative ways to synthesize silica glass at relatively low temperatures (≈1,000–1,200°C). Nuclear wastes exist as aqueous salt solutions and we propose using the open pore structure of the nanoporous glass to enable migration of the solution throughout the solid volume. The loaded material is then sintered, thereby trapping the radioactive chemical species. The structure of the sintered materials (glass ceramics) is that of nanocomposites: actinide phases (~100 nm) embedded in a vitreous silica matrix. Our results showed a large improvement in the chemical durability of glass ceramic over conventional nuclear glass.

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Sol-Gel Processing of Silica Nuclear Waste Glasses

Cited by 6 publications

References 23 publications

Porous glasses from aerogels: from organic liquid to mineral materials

Porous glasses from aerogels: from organic liquid to mineral materials

Candidate Low-Temperature Glass Waste Forms for Technetium-99 Recovered from Hanford Effluent Management Facility Evaporator Concentrate

Nanoporous Glasses for Nuclear Waste Containment

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