Publications
273 results found
Ojovan M, Mobus G, 2009, On radiation-induced fluidization (quasi-melting) of silicate glasses, Pages: 275-282, ISSN: 0272-9172
The effect of intensive electron radiation on viscous flow in silicate glasses is analysed and shown that it can result in a many orders of magnitude decrease of viscosity and stepwise decrease of activation energy of flow. Fluidisation or quasi-melting of glasses on intensive electron irradiation is caused by bond breaking via the radiation-chemical reaction ≡Si-O- Si≡ + e- → ≡Si-O + ≡Si + (e -)′ which weakens the silicate glass network and leads to five-fold coordination of oxygens around the silicon. An explicit equation of viscosity was obtained for irradiated glasses as well as an equation for glass transition temperature. The assessments of temperature increase by electron radiation show that radiation-induced fluidisation of glasses can occur at minimal thermal effects. Radiation-induced fluidisation of glasses can result in nanoscale patterning effects caused by surface tension forces. Changes in the viscous flow behaviour are also important in conditions of long-term irradiation for glasses used in nuclear installations as well as for nuclear waste glasses. © 2009 Materials Research Society.
Drace Z, Ojovan MI, 2009, The behaviours of cementitious materials in long term storage and disposal: An overview of results of the IAEA Coordinated Research Project, Pages: 663-672, ISSN: 0272-9172
Cementitious materials are widely used in waste management systems with different aims and requirements for long term performance. Both conventional and novel cementitious materials are used to create reliable immobilising elements for safe storage and disposal of wastes. The barrier elements as well as interactions envisaged between various components are important to ultimately ensure the overall safety of a storage/disposal system. The behaviour and performance of cementitious materials including waste package components, wasteform and backfilling were analysed within the IAEA Coordinated Research Project which involved 26 research organizations from 21 Member States MS). The paper presents briefly the main research outcomes for conventional cementitious systems; novel materials and technologies; testing and waste acceptance criteria; and modelling long term behaviour. © 2009 Materials Research Society.
Batyukhnova OG, Arustamov AE, Ojovan M, et al., 2009, Training activities and perspectives in the radioactive waste management area of moscow sia "radon", Pages: 665-670
The education service for specialists dealing with radioactive waste was established in Russia (former USSR) in 1983 and was based on the capabilities of two organisations: Moscow Scientific and Industrial Association «Radon» (SIA "Radon") and Lomonosov's Moscow State University. These two organizations are able jointly to offer training programs in the science fundamentals, applied research and in practical operational areas of the all pre-disposal activities of the radioactive waste management (RWM). Since 1997 this system was upgraded to the international level and now acts as the International Education Training Centre (IETC) at SIA "Radon" under the guidance of the IAEA. During last 12 years more than 350 specialists from 33 European and Asian countries enhanced their knowledge and skills in RWM. The IAEA supported many specialized regional training courses and workshops, fellowships, on-the-job training, and scientific visits which are additional means to assure development of personnel capabilities. Efficiency of training was analysed at IETC using the structural adaptation of educational process as well as factors, which have influence on education quality. In addition social-psychological aspects were also taken into account in assessing the overall efficiency. The analysis of the effect of individual factors and the efficiency of education activity were carried out based on appraisal results and post-course questioning of attendees. © 2009 by ASME.
Barinov AS, Varlakova GA, Startceva IV, et al., 2009, Infrared Spectroscopy Structural Analysis of Corroded Nuclear Waste Glass K-26, 32nd Symposium on Scientific Basis for Nuclear Waste Management held at the 2008 MRS Fall Meeting, Publisher: MATERIALS RESEARCH SOC, Pages: 167-173, ISSN: 0272-9172
Spasova LM, Ojovan MI, Hayes M, et al., 2009, ACOUSTIC EMISSION MONITORING OF CEMENT-BASED STRUCTURES IMMOBILISING RADIOACTIVE WASTE, 11th International Conference on Environmental Remediation and Radioactive Waste Management, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 631-638
Burakov B, Gribova V, Kitsay A, et al., 2009, SYNTHESIS OF CRYSTALLINE CERAMICS FOR ACTINIDE IMMOBILISATION, 11th International Conference on Environmental Remediation and Radioactive Waste Management, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 255-258
Barinov AS, Varlakova GA, Stefanovskii SV, et al., 2008, Change of structure and properties of vitrified radioactive wastes during long-time storage in an experimental repository, Atomic Energy, Vol: 105, Pages: 110-117, ISSN: 1063-4258
Scanning electron microscopy, x-ray phase analysis, and infrared spectroscopy are used to study samples selected from a near-surface zone of glass blocks of vitrified radioactive wastes from nuclear power plants after they have been in storage in an experimental repository for 17 years. It is shown that only a thin surface layer of the glass blocks undergoes any changes due to environmental factors, and quartz-like and alumosilicate embryos are found on this layer. © 2008 Springer Science+Business Media, Inc.
Spasova LM, Ojovan MI, 2008, Characterisation of Al corrosion and its impact on the mechanical performance of composite cement wasteforms by the acoustic emission technique, JOURNAL OF NUCLEAR MATERIALS, Vol: 375, Pages: 347-358, ISSN: 0022-3115
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- Citations: 18
Juoi JM, Ojovan MI, Lee WE, 2008, Microstructure and leaching durability of glass composite wasteforms for spent clinoptilolite immobilisation, JOURNAL OF NUCLEAR MATERIALS, Vol: 372, Pages: 358-366, ISSN: 0022-3115
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- Citations: 34
Ojovan MI, 2008, Configurons: Thermodynamic parameters and symmetry changes at glass transition, Entropy, Vol: 10, Pages: 334-364
Thermodynamic parameters of configurons - elementary excitations resulting from broken bonds in amorphous materials - are found from viscosity-temperature relationships. Glass-liquid transition phenomena and most popular models are described along with the configuron model of glass transition. The symmetry breaking, which occurs as a change of Hausdorff dimension of bonds, is examined at glass-liquid transition. Thermal history effects in the glass-liquid transition are interpreted in terms of configuron relaxation.
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- Citations: 74
Spasova LM, Gibb FGF, Ojovan MI, 2008, Characterisation of partial melting and solidification of granite E93/7 by the acoustic emission technique, Pages: 75-82, ISSN: 0272-9172
The acoustic emission (AE) technique was used to detect and characterise the processes associated with generation of stress waves during melting and solidification of granite E93/7 at a pressure of 0.15 GPa. The AE signals recorded as a result of partial melting of the granite at a temperature of 780°C and subsequent solidification during cooling were distinguished from the equipment noise and their parameters used to characterise the AE sources associated with the phase transformations during melting and solidification of the granite. The mechanisms generating AE during granite melting were differentiated by AE signals with their highest peaks in the frequency spectrum at 170 and 268 kHz. The transformation of the liquid into glass during solidification of the partially melted granite generated AE waves in an essentially broad range of frequencies between 100 and 300 kHz. This preliminary work demonstrates the potential of the AE technique for use in applications related to deep borehole disposal of radioactive wastes. © 2008 Materials Research Society.
Ojovan MI, Juoi JM, Boccaccini AR, et al., 2008, Glass Composite Materials for Nuclear and Hazardous Waste Immobilisation, Mater. Res. Soc. Symp. Proc., Vol: 1107
Ojovan MI, Juoi JM, Boccaccini AR, et al., 2008, Glass Composite Materials for Nuclear and Hazardous Waste Immobilisation, PA, USA, MRS Scientific Basis for Nuclear Waste Management XXXI, Publisher: Materials Research Society
Glass composite materials (GCM) are versatile wasteforms for immobilising various typesof both radioactive and hazardous wastes. We review current research on the utilisation of GCMsfor hazardous and radioactive waste immobilisation. Compared to homogeneous glassy materialsGCMs can incorporate larger amounts of waste elements and, in the case of glass matrixcomposites, they can be produced using lower processing temperatures (by viscous flowsintering) than those of conventional melting.
Ojovan MI, 2008, Viscosity and Glass Transition in Amorphous Oxides, Advances in Condensed Matter Physics, Vol: 2008, Pages: 1-23, ISSN: 1687-8108
<jats:p>An overview is given of amorphous oxide materials viscosity and glass-liquid transition phenomena. The viscosity is a continuous function of temperature, whereas the glass-liquid transition is accompanied by explicit discontinuities in the derivative parameters such as the specific heat or thermal expansion coefficient. A compendium of viscosity models is given including recent data on viscous flow model based on network defects in which thermodynamic parameters of configurons—elementary excitations resulting from broken bonds—are found from viscosity-temperature relationships. Glass-liquid transition phenomena are described including the configuron model of glass transition which shows a reduction of Hausdorff dimension of bonds at glass-liquid transition.</jats:p>
Moebus G, Yang G, Saghi Z, et al., 2008, Electron irradiation and electron tomography studies of glasses and glass nanocomposites, 31st Symposium on Scientific Basis for Nuclear Waste Management, Publisher: MATERIALS RESEARCH SOC, Pages: 239-244, ISSN: 0272-9172
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- Citations: 4
Spasova LM, Ojovan MI, 2007, Frequency characteristics of acoustic emission signals from cementitious wasteforms With encapsulated Al, Pages: 373-378, ISSN: 0272-9172
Acoustic emission (AE) signals were continuously recorded and their intrinsic frequency characteristics examined in order to evaluate the mechanical performance of cementitious wasteform samples with encapsulated Al waste. The primary frequency in the power spectrum and its range of intensity for the detected acoustic waves were potentially related with appearance of different micromechanical events caused by Al corrosion within the encapsulating cement system. In addition the process of cement matrix hardening has been shown as a source of AE signals characterized with essentially higher primary frequency (above 2 MHz) compared with those due to Al corrosion development (below 40 kHz) and cement cracking (above 100 kHz). © 2007 Materials Research Society.
Ojovan MI, Lee WE, 2007, New Developments in Glassy Nuclear Wasteforms, New York, Publisher: Nova Publishers, ISBN: 9781600217838
Based on the authors recent investigations, this book describes the application of glassy and polyphase composite materials for nuclear waste immobilisation.
Bergman GA, Karlina OK, Klimov VL, et al., 2007, Refinement of the thermodynamic functions of zirconolite at high temperatures, Atomic Energy, Vol: 103, Pages: 914-916, ISSN: 1063-4258
The thermodynamic functions of crystalline zirconolite CaZrTi 2O7 up to 1800 K and its melt up to 3000 K were investigated, with the measurements of the heat capacity in the interval 20-400 K. These results were extrapolated up to 1500 K. It has been observed that the extrapolation from 400 to 1500 K results in an overestimation of the component of the heat capacity due to the thermal expansion. The refined thermodynamic functions can be recommended for thermodynamic computations of high-temperature thermochemical processes with the participation of zirconolite.
Ojovan MI, Travis KP, Hand RJ, 2007, Thermodynamic parameters of bonds in glassy materials from viscosity–temperature relationships, Journal of Physics: Condensed Matter, Vol: 19, Pages: 415107-415107, ISSN: 0953-8984
Juoi JM, Ojovan MI, 2007, The effect of waste loading on the microstructure of glass composite waste forms for the immobilisation of spent clinoptilolite, GLASS TECHNOLOGY-EUROPEAN JOURNAL OF GLASS SCIENCE AND TECHNOLOGY PART A, Vol: 48, Pages: 124-129, ISSN: 1753-3546
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- Citations: 7
Pankov AS, Batyukhnova OG, Ojovan MI, et al., 2007, Simulation of self-irradiation of high-sodium content nuclear waste glasses, SCIENTIFIC BASIS FOR NUCLEAR WASTE MANAGEMENT XXX, Vol: 985, Pages: 353-+, ISSN: 0272-9172
Ojovan MI, Lee WE, 2006, Topologically disordered systems at the glass transition, JOURNAL OF PHYSICS-CONDENSED MATTER, Vol: 18, Pages: 11507-11520, ISSN: 0953-8984
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- Citations: 55
Spasova LM, Ojovan MI, 2006, Acoustic emission detection of microcrack formation and development in cementitious wasteforms with immobilised Al, JOURNAL OF HAZARDOUS MATERIALS, Vol: 138, Pages: 423-432, ISSN: 0304-3894
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- Citations: 10
Ojovan MI, Pankov A, Lee WE, 2006, The ion exchange phase in corrosion of nuclear waste glasses, JOURNAL OF NUCLEAR MATERIALS, Vol: 358, Pages: 57-68, ISSN: 0022-3115
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- Citations: 81
Ozhovan MI, 2006, Topological characteristics of bonds in SiO<inf>2</inf> and GeO<inf>2</inf> oxide systems upon a glass-liquid transition, Journal of Experimental and Theoretical Physics, Vol: 103, Pages: 819-829, ISSN: 1063-7761
Using the Angell model of broken bonds (configurons), configuron clustering in a topologically disordered lattice (network) of amorphous SiO2 and GeO2 upon a glass-liquid transition is considered. It is shown that the glass-liquid transition is accompanied by the formation of a macroscopic (percolation) configuron cluster penetrating the entire bulk of the material and possessing fractal geometry. The glass-liquid (overcooled liquid) percolation phase transition in the amorphous substance is accompanied by a change in the Hausdorff dimension of the bond network structure for configurons from the three-dimensional Euclidean dimension in the glassy state to a fractal dimension of 2.55 ± 0.05 in the liquidlike state. Contrary to the kinetic character of the liquid-glass transition, the glass-transition temperature is a thermodynamic parameter of the amorphous substance, depending parametrically on the cooling rate. © Nauka/Interperiodica 2006.
Manykin EA, Ojovan MI, Poluektov PP, 2006, Rydberg matter: Properties and decay, ISSN: 0277-786X
Rydberg matter is a condensed excited state made of highly excited atoms. State of art of research in the field of Rydberg matter is briefly reviewed. Special attention is focused on the contribution of Russian and Swedish scientists' groups to the analysis of this problem. Most attention is concentrated on physical principles of pseudopotential method and density functional theory used to describe the Rydberg matter. The description of Rydberg matter as an excited state becomes viable after the formal replacement of excited atoms by ground state pseudoatoms. This procedure has been used to find parameters of Rydberg matter made of highly excited cesium atoms. Theoretical estimations conform to experimental data available.
Ojovan MI, Lee WE, Barinov AS, et al., 2006, Corrosion of low level vitrified radioactive waste in a loamy soil, GLASS TECHNOLOGY-EUROPEAN JOURNAL OF GLASS SCIENCE AND TECHNOLOGY PART A, Vol: 47, Pages: 48-55, ISSN: 0017-1050
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- Citations: 16
Lee WE, Ojovan MI, Stennett MC, et al., 2006, Immobilisation of radioactive waste in glasses, glass composite materials and ceramics, ADVANCES IN APPLIED CERAMICS, Vol: 105, Pages: 3-12, ISSN: 1743-6753
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- Citations: 289
Sobolev IA, Dmitriev SA, Barinov AS, et al., 2006, 39-years performance of cemented radioactive waste in a mound type repository, Pages: 721-726, ISSN: 0272-9172
Long-term field tests of cemented aqueous radioactive wastes in an experimental mound type surface repository were carried out at Moscow Scientific and Industrial Association "Radon" from 1965 to 2004. Aqueous radioactive wastes of different compositions containing short-lived radionuclides including 90Sr and 137Cs at concentrations from 0.34 to 1.8 MBq/L were immobilized using cementation technology. Water solution to cement ratio was 0.66, grout mixing time 10-15 minutes, and cement paste hardening time 7 days. 73 cement blocks with a volume of 0.027 m 3 were disposed of for long-term tests in a simple mound type surface repository. The atmospheric precipitates, which contacted radioactive cement blocks, were collected and analyzed for the content of radionuclides. In August 2004 the experimental repository was opened, cemented blocks, underlying and covering materials were retrieved for analyses. XRD analyses showed that along with amorphous tobermorite gel the main crystal phases in cements are calcite and portlandite. Both visual inspection and radiometric analyses demonstrate that cemented blocks are in good condition and that the cement paste has retained radionuclides from the wastes. Thus after 39 years of storage in the mound type repository the cemented aqueous wastes are reliable immobilized. © 2006 Materials Research Society.
Spasova LM, Ojovan M, Scales CR, 2006, Acoustic emission monitoring of Al corrosion in cemented-based wasteforms, 27th European Conference on Acoustic Emission Testing, Publisher: TRANS TECH PUBLICATIONS LTD, Pages: 223-+, ISSN: 1022-6680
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- Citations: 5
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