A review on immobilization of phosphate containing high level nuclear wastes within glass matrix – Present status and future challenges

Sengupta, P.

doi:10.1016/j.jhazmat.2012.07.039

Cited by 93 publications

(29 citation statements)

References 115 publications

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“…It is also noteworthy that all the σ values are higher than the values expected from a linear evolution from the pure phosphate to the pure borate compositions. This effect, called the mixed glass former effect (MGFE), has been highlighted in different compositions for conductivity [18,20,21] and other macroscopic properties, such as the glass transition temperature (Tg) [7][8][9] or the kinetic fragility [22]. A representative example is given in Figure 1b where the Tg evolution observed in the 45Li 2 O-xB 2 O 3 -(55-x)P 2 O 5 system is reported [19].…”

Section: Introductionmentioning

confidence: 96%

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Solid State NMR: A Powerful Tool for the Characterization of Borophosphate Glasses

2020

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This review will show how solid state nuclear magnetic resonance (NMR) has contributed to a better understanding of the borophosphate glass structure. Over the last fifteen years, 1D and 2D magic angle spinning (MAS)-NMR has been used to produce key information about both local and medium range organization in this type of glass. After a brief presentation on borophosphate glasses, the paper will focus on the description of the local order of phosphate and borate species obtained by 1D 31P-and 11B-MAS-NMR experiments, with a special emphasis on the improvements obtained at high magnetic fields on the borate speciation description. The last part of this review will show how correlation NMR provided new insights into the intermediate length scale order. Special attention will be paid to the quantitative data retrieved from 11B/31P REDOR-based NMR sequences and to the qualitative connectivity schemes observed on the 2D 11B/31P maps edited with the heteronuclear multiple quantum coherence (HMQC) NMR techniques.

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Section: Introductionmentioning

confidence: 96%

“…and technical uses (optical fibers, sealing glasses, waste confinement matrixes, coatings, etc.) [1][2][3][4][5][6][7][8]. A large proportion of these glasses are called 'silicate' since their structural backbone (called the glass network) is formed by interconnected silica tetrahedra SiO 4 4-.…”

Section: Introductionmentioning

confidence: 99%

Solid State NMR: A Powerful Tool for the Characterization of Borophosphate Glasses

2020

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“…The restricted solubility of compounds, such as P 2 O 5 , sulfates, halides, and actinides, in silicate melts has encouraged waste-form designers to once again judge the potential of P 2 O 5 -based glass systems as host matrices [9]. Many studies on "composition-property-structure correlations" in various phosphate-based glasses and waste glasses have already been conducted, and some of these phosphate glasses are considered very promising, as they are chemically durable, thermally stable, and can be processed at moderate temperatures.…”

Section: Introductionmentioning

confidence: 99%

Immobilization of simulated radioactive fluoride waste in phosphate glass

et al. 2016

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Radioactive alkali fluoride salts are generated during the operation of molten salt reactors (MSRs) and reprocessing of their spent fuel, and appear in the form of fluidity granule, or powder. In order to prevent the radionuclides from being released into the environment (especially, via exposure to water), it is necessary to develop a new technology for the temporary storage or final disposal of wastes containing radioactive fluorides. The immobilization of alkali fluoride wastes in phosphate glasses has been proposed. In this study, iron phosphate (IP) glasses and sodium aluminophosphate (NaAlP) glasses were evaluated for the immobilization of simulated radioactive fluoride wastes. IP and NaAlP glass matrixes were mixed with simulated wastes and reacted in air at temperatures in the range of 950-1200°C. A high waste loading was obtained in the experiment. The properties of the waste forms were characterized by X-ray diffraction and Raman spectroscopy. The latter indicated that IP glass contains less Q 2 without Q 3 (2 and 3 represent the number of bridging oxygens on a PO4 tetrahedron), and it is concluded that IP glass is more stable than NaAlP glass. Leaching tests were performed in deionized water by using the product consistency test A (PCT-A method), and the result shows that the leaching resistance of IP waste forms is better than that of NaAlP waste forms. This study demonstrates the potential of IP glass for the stabilization and immobilization of radioactive fluoride wastes from MSRs.

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“…However, such an approach leads to the production of higher waste glass volume which also delays “back‐end facilities” cleanup schedule. As an alternative to this, three different routes are being tried across the world which include identification of (i) efficient and selective sulfate separator, (ii) adoption of different waste form matrices, and (iii) reformulation of glass composition to accommodate higher amount of waste . Present study is a part of ongoing investigations focused on third option where efforts are being made to modify the amorphous network of sodium barium borosilicate glass matrix (indigenously developed to condition SO 3 ‐HLW 29 ) through addition of V 2 O 5 .…”

Section: Introductionmentioning

confidence: 99%

Vanadium in Borosilicate Glass

et al. 2014

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Understanding the role of V 2 O 5 within borosilicate glass matrices is important for the development of novel matrices toward immobilization of sulfate containing high-level nuclear wastes. Present investigation shows, within sodium barium borosilicate glass matrix V 2 O 5 can be homogeneously added up to 5 mol% and beyond which it separates out into three phases, for example, (i) silica (ii) Barium (Ba) -Vanadium (V) oxide, and (iii) glass matrix. 29 Si MAS NMR (Nuclear Magnetic Resonance) studies of the samples show that below 5 mol% V 2 O 5 addition, silicate network is dominantly constituted of Q 2 and Q 3 structural units, whereas above this, the network gets more polymerized through formation of Q 3 and Q 4 units. In case of borate network, 11 B MAS NMR investigations revealed that the concentration of BO 4 [(0B, 4Si)] unit increases gradually up to 5 mol% and then it decreases at the cost of BO 4 [(1B, 3Si)], BO 3 (symmetric) and BO 3 (asymmetric) units. Micro-Raman analyses of the samples showed that with additions of V 2 O 5 in diluted concentrations, amorphous silicate network remained unaltered, whereas some amplification in signals corresponding to ring-type metaborate and VO 5 units exists. It is therefore apparent from both MAS-NMR and micro-Raman studies that with V 2 O 5 additions within the solubility limit (≤5 mol%), borate network gets depolymerized leading to decrease in hardness from an average value of 5.0-4.2 GPa.(1) V 2 O 5 as Amorphous Network Modifier The idea of using V 2 O 5 within glass matrices to enhance sulfate solubility was first put forward by Russian scientists. 35 According to them, the match between sulfate crystallochemical parameters and glass structure plays a crucial role in determining sulfate solubility. The important parameters which decide such compatibility include (i) cation-oxygen binding energy; (ii) Dietzel field strength (z c /a 2 , where "z" is charge of the cation and "a" is sum of cation radius and O 2À radius); (iii) z c /k bond strength, where "k" is the coordination number of the cation; and (iv) size and polarization of the polyhedra. 12,35 These considerations yielded following cation distribution series: L. Pinckney-contributing editor Manuscript No. 34981.

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A review on immobilization of phosphate containing high level nuclear wastes within glass matrix – Present status and future challenges

Cited by 93 publications

References 115 publications

Solid State NMR: A Powerful Tool for the Characterization of Borophosphate Glasses

Solid State NMR: A Powerful Tool for the Characterization of Borophosphate Glasses

Immobilization of simulated radioactive fluoride waste in phosphate glass

Vanadium in Borosilicate Glass

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