Phase Composition, Structure, and Hydrolytic Stability of Sodium-Aluminum(Iron) Phosphate Glass Containing Rare-Earth Oxides

Stefanovskii, S. V.; Stefanovskaya, O. I.; Семенова, Д. В.; Кадыко, М. И.; Danilov, S. S.

doi:10.1007/s10717-018-0034-5

Cited by 9 publications

(7 citation statements)

References 14 publications

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“…At the final stage of leaching (72 days), the leaching rates of Ln, Sr, and Zr elements reached∼10 −5 g·m −2 ·d −1 , ∼10 −3 g·m −2 ·d −1 , and∼10 −7 g·m −2 ·d −1 , respectively. These values are comparable to the leaching rates of typical synroc waste forms and lower than those of glass waste forms 15,16,23–25 . Compared with the previously reported waste form of pyrochlore glass ceramics, the leaching rate of Ln and Zr elements in multiphase ceramics is 1–2 orders of magnitude lower 26,27 .…”

Section: Resultssupporting

confidence: 69%

“…These values are comparable to the leaching rates of typical synroc waste forms and lower than those of glass waste forms. 15,16,[23][24][25] Compared with the previously reported waste form of pyrochlore glass ceramics, the leaching rate of Ln and Zr elements in multiphase ceramics is 1-2 orders of magnitude lower. 26,27 The element leaching rate at the A site of single-phase (Gd, A) 2 (Zr, B) 2 O 7 pyrochlore is on the order of 10 −4 , while the element leaching rate at the A site of multiphase ceramic waste form is on the order of 10 −5 .…”

Section: Evaluation Of the Chemical Durabilitymentioning

confidence: 90%

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Preparation and chemical stability evaluation of Ln₂Zr₂O₇‐SrZrO₃ novel composite ceramics cured simultaneously with An and ⁹⁰Sr

Xie,

Liu,

Lan

et al. 2023

Int J Applied Ceramic Tech

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In response to the low separation efficiency of actinide nuclide (An) and fission product (FP) in the separation process of high‐level radioactive waste, as well as the large amount of secondary waste. A novel Ln(1‐x)SrxZrO(3.5‐0.5x) (0 ≤ x ≤1) multiphase ceramic waste form (Nd3+ simulating An3+), which can cure both An and Sr simultaneously, was in‐situ synthesized by sol‐gel spray pyrolysis method. The series of multiphase ceramics are composed of cubic pyrochlore phase Nd2Zr2O7 (NZO) and orthorhombic perovskite phase SrZrO3 (SZO), without any accompanying impurities. The two phases exhibit excellent compatibility, and their content can change regularly with the change of x. Nd and Sr occupy their most stable crystal lattice positions, with low transposition doping levels. The density of the composite ceramics is high, and the measured density is as high as 88 % of the theoretical density. The above experimental results confirm that the new multiphase ceramics can cure An and Sr simultaneously and separately, showing strong adaptability to waste components and high chemical stability.

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Section: Resultssupporting

confidence: 69%

Section: Evaluation Of the Chemical Durabilitymentioning

confidence: 90%

Preparation and chemical stability evaluation of Ln₂Zr₂O₇‐SrZrO₃ novel composite ceramics cured simultaneously with An and ⁹⁰Sr

Xie,

Liu,

Lan

et al. 2023

Int J Applied Ceramic Tech

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“…Phosphate glass-ceramics with monazite are described in [32,[83][84][85][86][87][88][89][90][91][92][93][94][95][96][97][98]. Industrial immobilization of HLW in B-Si glass in the world has been carried out since the 1970s; in Russia, since the 1980s, an Al-P composition has been used for this purpose.…”

Section: Monazite Glass-ceramicsmentioning

confidence: 99%

“…The spherulites practically do not contain any REEs. Alumina phosphate (SAP) and alumina-iron phosphate (SAIP) glasses with REEs and actinides (U, Np, Pu, Am) have been studied [88,[93][94][95] (SAIP). The REE content varied from 1 to 20 wt.%, and from less than 1 wt.% (Np, Pu, Am) to 50 wt.% (U) for actinides.…”

Section: Monazite Glass-ceramicsmentioning

confidence: 99%

Thermal Effects and Glass Crystallization in Composite Matrices for Immobilization of the Rare-Earth Element–Minor Actinide Fraction of High-Level Radioactive Waste

Yudintsev,

Ojovan,

Malkovsky

2024

J. Compos. Sci.

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The current policy of managing high-level waste (HLW) derived in the closed nuclear fuel cycle consists in their vitrification into B-Si or Al-P vitreous forms. These compounds have rather limited capacity with respect to the HLW (5–20 wt%), and their properties change over time due to devitrification of the glasses. Cardinal improvement in the management of HLW can be achieved by their separation onto groups of elements with similar properties, followed by their immobilization in robust waste forms (matrices) and emplacement in deep disposal facilities. One of the possible fractions contains trivalent rare-earth elements (REEs) and minor actinides (MAs = Am and Cm). REEs are the fission products of actinides, which are mainly represented by stable isotopes of elements from La to Gd as well as Y. This group also contains small amounts of short-lived radionuclides with half-lives (T1/2) from 284 days (144Ce) to 90 years (151Sm), including 147Pm (T1/2 = 2.6 years), 154Eu (T1/2 = 8.8 years), and 155Eu (T1/2 = 5 years). However, the main long-term environmental hazard of the REE–MA fraction is associated with Am and Cm, with half-lives from 18 years (244Cm) to 8500 years (245Cm), and their daughter products: 237Np (T1/2 = 2.14 × 106 years), 239Pu (T1/2 = 2.41 × 104 years), 240Pu (T1/2 = 6537 years), and 242Pu (T1/2 = 3.76 × 105 years), which should be immobilized into a durable waste form that prevents their release into the environment. Due to the heat generated by decaying radionuclides, the temperature of matrices with an REE–MA fraction will be increased by hundreds of centigrade above ambient. This process can be utilized by selecting a vitreous waste form that will crystallize to form durable crystalline phases with long-lived radionuclides. We estimated the thermal effects in a potential REE–MA glass composite material based on the size of the block, the content of waste, the time of storage before immobilization and after disposal, and showed that it is possible to select the waste loading, size of blocks, and storage time so that the temperature of the matrix during the first decades will reach 500–700 °C, which corresponds to the optimal range of glass crystallization. As a result, a glass–ceramic composite will be produced that contains monazite ((REE,MA)PO4) in phosphate glasses; britholite (Cax(REE,MA)10-x(SiO4)6O2) or zirconolite ((Ca,REE,MA)(Zr,REE,MA)(Ti,Al,Fe)2O7), in silicate systems. This possibility is confirmed by experimental data on the crystallization of glasses with REEs and actinides (Pu, Am). The prospect for the disposal of glasses with the REE–MA fraction in deep boreholes is briefly considered.

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“…The samples of NAFP glass with the composition, mol%: 40Na 2 O-10Al 2 O 3 -10Fe 2 O 3 -40P 2 O 5 , which has high crystallization and hydrolytic stability [22][23][24], were synthesized with 10 wt% of the spent electrolyte imitator in the form of dry salts. The samples were synthesized by melting up to 1200 • C in quartz crucibles with isothermal holding of the resulting melts for 1 h and then pouring onto a metal sheet for glass quenching.…”

Section: Synthesis Of Nafp Glassmentioning

confidence: 99%

Perspective Compounds for Immobilization of Spent Electrolyte from Pyrochemical Processing of Spent Nuclear Fuel

et al. 2021

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Immobilization of spent electrolyte–radioactive waste (RW) generated during the pyrochemical processing of mixed nitride uranium–plutonium spent nuclear fuel is an acute task for further development of the closed nuclear fuel cycle with fast neutron reactors. The electrolyte is a mixture of chloride salts that cannot be immobilized directly in conventional cement or glass matrix. In this work, a low-temperature magnesium potassium phosphate (MPP) matrix and two types of high-temperature matrices (sodium aluminoironphosphate (NAFP) glass and ceramics based on bentonite clay) were synthesized. Two systems (Li0.4K0.28La0.08Cs0.016Sr0.016Ba0.016Cl and Li0.56K0.40Cs0.02Sr0.02Cl) were used as spent electrolyte imitators. The phase composition and structure of obtained materials were studied by XRD and SEM-EDS methods. The differential leaching rate of Cs from MPP compound and ceramic based on bentonite clay was about 10−5 g/(cm2·day), and the rate of Na from NAFP glass was about 10−6 g/(cm2·day). The rate of 239Pu from MPP compound (leaching at 25 °C) and NAFP glass (leaching at 90 °C) was about 10−6 and 10−7 g/(cm2·day), respectively. All the synthesized materials demonstrated high hydrolytic, mechanical compression strength (40–50 MPa) even after thermal (up to 450 °C) and irradiation (up to 109 Gy) tests. The characteristics of the studied matrices correspond to the current requirements to immobilized high-level RW, that allow us to suggest these materials for industrial processing of the spent electrolyte.

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Phase Composition, Structure, and Hydrolytic Stability of Sodium-Aluminum(Iron) Phosphate Glass Containing Rare-Earth Oxides

Cited by 9 publications

References 14 publications

Preparation and chemical stability evaluation of Ln₂Zr₂O₇‐SrZrO₃ novel composite ceramics cured simultaneously with An and ⁹⁰Sr

Preparation and chemical stability evaluation of Ln₂Zr₂O₇‐SrZrO₃ novel composite ceramics cured simultaneously with An and ⁹⁰Sr

Thermal Effects and Glass Crystallization in Composite Matrices for Immobilization of the Rare-Earth Element–Minor Actinide Fraction of High-Level Radioactive Waste

Perspective Compounds for Immobilization of Spent Electrolyte from Pyrochemical Processing of Spent Nuclear Fuel

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Phase Composition, Structure, and Hydrolytic Stability of Sodium-Aluminum(Iron) Phosphate Glass Containing Rare-Earth Oxides

Cited by 9 publications

References 14 publications

Preparation and chemical stability evaluation of Ln2Zr2O7‐SrZrO3 novel composite ceramics cured simultaneously with An and 90Sr

Preparation and chemical stability evaluation of Ln2Zr2O7‐SrZrO3 novel composite ceramics cured simultaneously with An and 90Sr

Thermal Effects and Glass Crystallization in Composite Matrices for Immobilization of the Rare-Earth Element–Minor Actinide Fraction of High-Level Radioactive Waste

Perspective Compounds for Immobilization of Spent Electrolyte from Pyrochemical Processing of Spent Nuclear Fuel

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Preparation and chemical stability evaluation of Ln₂Zr₂O₇‐SrZrO₃ novel composite ceramics cured simultaneously with An and ⁹⁰Sr

Preparation and chemical stability evaluation of Ln₂Zr₂O₇‐SrZrO₃ novel composite ceramics cured simultaneously with An and ⁹⁰Sr