Geological aspects of the nuclear waste disposal problem

Лаверов, Н. П.; Omelianenko, B.L.; Величкин, В. И.

doi:10.2172/91959

Cited by 10 publications

(8 citation statements)

References 6 publications

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“…Irradiation of the titanate matrix with the dose lower by an order of magnitude results in the appearance of wide rings instead of the pattern with point maxima, which provides evidence for amorphization of the crystal framework. The dose of its amorphization is 3 × 10 14 ion/cm 2 , which is close to the values for La 2 Ti 2 O 7 of the same structure [13], as well as to the stability of some titanate pyrochlores, for example Gd 2 Ti 2 O 7 , CaСеTi 2 O 7 , and CaUTi 2 O 7 [1,6].…”

Section: Phase Composition and Radiation Stability Of Matrices For Issupporting

confidence: 79%

“…Let us compare these data with the results on the stability of other matrices [1][2][3][6][7][8][9][10]. It is conve nient to use the values of doses expressed in diplace ments by one atom of the framework (dpa).…”

Section: Phase Composition and Radiation Stability Of Matrices For Ismentioning

confidence: 99%

“…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.…”

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confidence: 99%

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

Лаверов

Yudintsev

Stefanovsky³

et al. 2012

Dokl. Earth Sc.

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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...

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Section: Phase Composition and Radiation Stability Of Matrices For Issupporting

confidence: 79%

Section: Phase Composition and Radiation Stability Of Matrices For Ismentioning

confidence: 99%

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

Лаверов

Yudintsev

Stefanovsky³

et al. 2012

Dokl. Earth Sc.

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“…As is known, these types of anomalies are associated with tectonic structures in the upper part of the earth crust-faults, the boundaries of large blocks, linear structures, potential zones of possible earthquakes, etc. These are geodynamic zones that pose the biggest threat to the isolation properties of the greatest [2]. Their search is mandatorily regulated by the statutory documents applicable in the field of HLRW disposal.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Framework for Determination of Linear Structures in Multidimensional Geodynamic Data Arrays

et al. 2021

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The article addresses the issue of clustering of multidimensional data arrays with a noise using the methods of discrete mathematical analysis (DMA clustering). The theory of DMA clustering through the logical densities calculus is detailed, and the new algorithm Linear Discrete Perfect Sets (LDPS) is described. The main objective of the LDPS algorithm is to identify linearly stretched anomalies in a multidimensional array of geo-spatial data (geophysical fields, geochemistry, satellite images, local topography, maps of recent crustal movements, seismic monitoring data, etc.). These types of anomalies are associated with tectonic structures in the upper part of the Earth’s crust and pose the biggest threat for integrity of the isolation properties of the geological environment, including in regions of high-level radioactive waste disposal. The main advantage of the LDPS algorithm as compared to other cluster analysis algorithms that may be used in arrays with a noise is that it is more focused on searching for clusters that are linear. The LDPS algorithm can apply not only in the analysis of spatial natural objects and fields but also to elongated lineament structures.

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“…The underground engineering projects of burying HLW are called geological repositories [8,9]. The construction conditions of a geological repository are complex.…”

Section: Introductionmentioning

confidence: 99%

Development and Application of an Intelligent Test System for the Model Test on Deep Underground Rock Caverns

et al. 2020

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The safe disposal of high-level radioactive waste (HLW) is a major issue to ensure environmental protection and the sustainable development of the nuclear energy industry; it is also an equally important issue regarding nuclear safety. Deep-buried geological disposal is recognized worldwide as the safest and most feasible way to protect human beings and the environment. To satisfy the research functions, most underground research laboratories (URLs) for geological repositories are buried deeply, and their layout is quite complex. To research nonlinear deformation characteristics and failure mechanism of deep underground caverns in the process of construction, we developed an intelligent true triaxial non-uniform loading/unloading model test system. The system has the advantages of a large rated output, starting from zero pressure, cyclic loading and unloading, high loading accuracy and displacement test accuracy, and arbitrary adjustment of device size. We carried out a true three-dimensional physical model test, taking the URL for the deep-buried geological disposal of HLW in Beishan area, Gansu Province as the prototype. The nonlinear deformation characteristics and the law of displacement change of the underground laboratory caverns are reproduced. We observed the whole process, from the appearance of micro cracks to the expansion of the cracks and the collapse of the cavern group. This provides an important experimental basis for optimizing the design and construction of URL for the deep-buried geological disposal of HLW. The value and slope of displacement calculated by the numerical simulation are mainly the same as the experimental results of the geological model test, which validates the accuracy and reliability of the model test system in this study.

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Geological aspects of the nuclear waste disposal problem

Cited by 10 publications

References 6 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

Theoretical Framework for Determination of Linear Structures in Multidimensional Geodynamic Data Arrays

Development and Application of an Intelligent Test System for the Model Test on Deep Underground Rock Caverns

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