Murataite matrices for actinide wastes

Лаверов, Н. П.; Yudintsev, S. V.; Stefanovskii, S. V.; Omel’yanenko, B. I.; Никонов, Б. С.

doi:10.1134/s1066362211030027

Cited by 22 publications

(13 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The incom pleteness of reactions in the systems with a high zirco nium concentration and preservation of relict Zr and Gd oxides were previously observed in synthesis of the matrix with the composition Gd 2 Zr 2 O 7 [4].…”

Section: Phase Composition and Radiation Stability Of Matrices For Ismentioning

confidence: 82%

“…The starting charge was prepared from TiO 2 , ZrO 2 , and a mixture of REE oxides taken in proportions cor responding to the ideal formula (REE) 2 4.7 (or in atomic proportions: 0.24La + 0.46Ce + 0.21Pr + 0.75Nd + 0.15Sm + 0.02Eu + 0.03Gd + 0.14Y); they reflect the proportions between them in the REEactinide fraction of wastes from reprocessing of irradi ated nuclear fuel. The size of the Nd 3+ cation is close to the sizes of the Am 3+ and Cm 3+ cations, that is why it was an imitator of these actinides.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Phase composition and radiation stability of matrices for isolation of REE-actinide waste

Лаверов

Yudintsev

Stefanovsky³

et al. 2012

Dokl. Earth Sc.

Self Cite

View full text Add to dashboard Cite

526Safe treatment with highly radioactive wastes from processing of irradiated fuel is a key problem at the final stage of the nuclear energy cycle. The waste prod ucts are currently immobilized in glassy matrices for loading in underground storage [1]. Glasses are insuf ficiently stable for isolation of long living radionu clides, including actinides. It is suggested to fraction ate such wastes and include long living nuclides in the most stable crystalline matrices in order to increase safety [2]. The available technologies allow us to sepa rate actinides (U, Np, Pu), the REE-actinide compo nent, and products of decay.Zirconates and titanates with the structures of pyrochlore, zirconolite, perovskite, murataite, and others are suggested for isolation of actinide wastes [1-10 and others]. Materials with wastes of simple composition (plutonium and its imitators) were basi cally studied in these investigations; less attention was given to matrices for immobilization of the REEactinide fraction. Its approximate composition is the following (wt %): 80-90 REE + 10-20 actinides, where light lanthanides (La, Ce, Pr, Nd, and Sm) pre vail among REEs, and actinides are mainly repre sented by Am and Cm. The structure of matrices undergoes changes during actinide decay, which may influence their isolation properties.In this paper we report the new data on the struc tural peculiarities of perspective matrices for the REE actinide fraction and their radiation stability during irradiation by accelerated krypton ions.The starting charge was prepared from TiO 2 , ZrO 2 , and a mixture of REE oxides taken in proportions cor responding to the ideal formula (REE) 2 Zr 2 -x Ti x O 7 , where х = 0 (Sample Z) or 2 (Sample T). The propor tions of elements in the REE mixture are the following (wt %): La 4.7 (or in atomic proportions: 0.24La + 0.46Ce + 0.21Pr + 0.75Nd + 0.15Sm + 0.02Eu + 0.03Gd + 0.14Y); they reflect the proportions between them in the REEactinide fraction of wastes from reprocessing of irradi ated nuclear fuel. The size of the Nd 3+ cation is close to the sizes of the Am 3+ and Cm 3+ cations, that is why it was an imitator of these actinides. The mixtures were homogenized carefully and pressed into tablets at 200 atm and 25°С, and after that they were loaded in the oven for 5 h at 1550°С (х = 0) or 1400°С (х = 2). Reaching equilibrium in the zirconate system requires higher temperatures for acceleration of the phase for mation during synthesis. The samples were studied by X ray diffraction (XRD) and on a scanning electron microscope equipped with an energy dispersive spec trometer (SEM/EDS). They were irradiated in the Argonne National Laboratory (United States) on an accelerator combined with a transmission electron microscope [7]. This approach allows us to observe disordering of atoms in the framework and destruction upon irradiation. This method is an express way to determine the doses of amorphization in a wide tem perature range [1-3, 6-8, and others].According to the XRD data, Sample Z consists of dominating pyro...

show abstract

Section: Phase Composition and Radiation Stability Of Matrices For Ismentioning

confidence: 82%

mentioning

confidence: 99%

Phase composition and radiation stability of matrices for isolation of REE-actinide waste

Лаверов

Yudintsev

Stefanovsky³

et al. 2012

Dokl. Earth Sc.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The crystal structure of zunyite, Al 13 Si 5 O 20 (OH,F) 18 Cl (Baur & Ohta, 1982) (Ercit & Hawthorne, 1995). The synthetic analogue of murataite-(Y) and the titanate-based ceramics of the murataite-pyrochlore series have a high potential as matrices for the immobilization of high-level radioactive waste products with complex chemical composition (Morgan & Ryerson, 1982;Laverov et al, 1998;Krivovichev et al, 2010;Pakhomova et al, 2013Pakhomova et al, , 2016.…”

Section: Polyoxovanadatesmentioning

confidence: 99%

Polyoxometalate clusters in minerals: review and complexity analysis

Krivovichev¹

2020

Acta Crystallogr B Struct Sci Cryst Eng Mater

View full text Add to dashboard Cite

Most research on polyoxometalates (POMs) has been devoted to synthetic compounds. However, recent mineralogical discoveries of POMs in mineral structures demonstrate their importance in geochemical systems. In total, 15 different types of POM nanoscale-size clusters in minerals are described herein, which occur in 42 different mineral species. The topological diversity of POM clusters in minerals is rather restricted compared to the multitude of moieties reported for synthetic compounds, but the lists of synthetic and natural POMs do not overlap completely. The metal–oxo clusters in the crystal structures of the vanarsite-group minerals ([As3+V4+ 2V5+ 10As5+ 6O51]7−), bouazzerite and whitecapsite ([M 3+ 3Fe7(AsO4)9O8–;n (OH) n ]), putnisite ([Cr3+ 8(OH)16(CO3)8]8−), and ewingite ([(UO2)24(CO3)30O4(OH)12(H2O)8]32−) contain metal–oxo clusters that have no close chemical or topological analogues in synthetic chemistry. The interesting feature of the POM cluster topologies in minerals is the presence of unusual coordination of metal atoms enforced by the topological restraints imposed upon the cluster geometry (the cubic coordination of Fe3+ and Ti4+ ions in arsmirandite and lehmannite, respectively, and the trigonal prismatic coordination of Fe3+ in bouazzerite and whitecapsite). Complexity analysis indicates that ewingite and morrisonite are the first and the second most structurally complex minerals known so far. The formation of nanoscale clusters can be viewed as one of the leading mechanisms of generating structural complexity in both minerals and synthetic inorganic crystalline compounds. The discovery of POM minerals is one of the specific landmarks of descriptive mineralogy and mineralogical crystallography of our time.

show abstract

“…In addition, the main diffraction peaks of the supercells, derived from the similar basic sub-cells, means, close overlaps occur for all the polytypes at all the strongest peaks (Laverov et al, 2011b). Therefore, for quick analysis, we need accurate XRPD patterns especially emphasizing the lowest angle lines where these complex polytypes are most readily distinguishable.…”

mentioning

confidence: 99%

X-ray powder diffraction characterization of the large-volume unit cell of the M8 murataite polytype

2016

View full text Add to dashboard Cite

We have used conventional X-ray powder diffraction to study one of the largest volume inorganic mixed oxide unit supercell structures done so far. This necessitated some SAXS-like observations at low angles from < 2° 2θ to concord with electron diffraction, which had indicated an 8×8×8 huge volume supercell of a fluorite-type basic sub-cell.Emphasis is on the detection of, possibly very weak, fingerprint, low-angle/long lines/peaks which will indicate the (often unsuspected) presence of complex polytypic arrangements of simple very strong basic sub-cells and so facilitate synthetic studies.

show abstract

Murataite matrices for actinide wastes

Cited by 22 publications

References 5 publications

Phase composition and radiation stability of matrices for isolation of REE-actinide waste

Phase composition and radiation stability of matrices for isolation of REE-actinide waste

Polyoxometalate clusters in minerals: review and complexity analysis

X-ray powder diffraction characterization of the large-volume unit cell of the M8 murataite polytype

Contact Info

Product

Resources

About