| 1. |
- Almjashev, V.I., et al.
(author)
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Eutectic crystallization in the FeO(1.5)-UO(2+x)-ZrO(2) system
- 2009
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In: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 389:1, s. 52-56
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Journal article (peer-reviewed)abstract
- Results of the investigation of the FeO(1.5)-UO(2+x)-ZrO(2) system in air are presented. The eutectic position and the content of the phases crystallized at this point have been determined. The temperature and the composition of the ternary eutectic are 1323 +/- 7 degrees C and 67.4 +/- 1.0 FeO(1.5), 30.5 +/- 1.0 UO(2+x), 2.1 +/- 0.2 ZrO(2) mol.%, respectively. The solubilities of FeO(1.5) and ZrO(2) in the UO(2+x)(FeO(1.5), ZrO(2)) solid solution correspond to respectively 3.2 and 1.1 mol.%. The solubilities of UO(2) and ZrO(2) in FeO(1.5) are not significant. The existence of a solid solution on the basis of U(Zr)FeO(4) compound is found. The ZrO(2) Solubility in this solid solution is 7.0 mol.%.
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| 2. |
- Almjashev, V.I., et al.
(author)
-
Phase equilibria in the FeO(1+x)-UO(2)-ZrO(2) system in the FeO(1+x)-enriched domain
- 2010
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In: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 400:2, s. 119-126
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Journal article (peer-reviewed)abstract
- Experimental results of the investigation of the FeO(1+x)UO(2)-ZrO(2) system in neutral atmosphere are presented. The ternary eutectic position and the composition of the phases crystallized at this point have been determined. The phase diagram is constructed for the FeO(1+x)-enriched region and the onset melting temperature of 1310 degrees C probably represents a local minimum and so will be a determining factor in this system and its application to safety studies in nuclear reactors.
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| 3. |
- Almjashev, V.I., et al.
(author)
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Ternary eutectics in the systems FeO-UO2-ZrO2 and Fe2O3-U3O8-ZrO21
- 2011
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In: Radiochemistry. - 1066-3622. ; 53:1, s. 13-18
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Journal article (peer-reviewed)abstract
- The systems FeO–UO2–ZrO2 (in inert atmosphere) and Fe2O3–U3O8–ZrO2 (in air) were studied. Forthe FeO–UO2–ZrO2 system, the eutectic temperature was found to be 1310°С, with the following componentconcentrations (mol %): 91.8 FeO, 3.8 UO2, and 4.4 ZrO2. For the Fe2O3–U3O8–ZrO2 system, the eutectictemperature was found to be 1323°С, with the following component concentrations (mol %): 67.4 FeO1.5,30.5 UO2.67, and 2.1 ZrO2. The solubility limits of iron oxides in the phases based on UO2(ZrO2,FeO) andUO2.67(ZrO2,FeO1.5) were determined
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| 4. |
- Bechta, Sevostian, et al.
(author)
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CORPHAD and METCOR ISTC projects
- 2005
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In: Proceedings of The first European Review Meeting on Severe Accident Research (ERMSAR-2005).
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Conference paper (peer-reviewed)abstract
- The ongoing CORPHAD Project (Phase Diagrams for Multicomponent SystemsContaining Corium and Products of its Interaction with NPP Materials) started in August2001. The main aim of the project is to experimentally determine the relevantphysicochemical data on phase diagrams of binary, ternary, quaternary and prototypic multicomponent systems, which are important for analysis and modelling of a severe accident (SA)and efficient planning of severe accident management (SAM) measures. The data should bedirectly used for the European NUCLEA database development and validation. The followingsystems are in the focus of the project: (1) UO2 – FeO, (2) ZrO2 – FeO, (3) SiO2– Fe2O3, (4)UO2 – SiO2, (5) UO2 – ZrO2-FeO, (6) UO2 – ZrO2-FeOy, (7) U-O-Fe, (8) Zr-O-Fe, (9) U-OZr, (10) U-Zr-Fe-O, (11) complex corium mixtures.The experimentally determined data of the listed diagrams include: coordinates ofcharacteristic points (eutectics, peritectics and others); liquidus and solidus concentrationcurves; component solubility limits in the solid phase; tie line coordinates and temperatureconcentration regions of the miscibility gap. Different methodologies are used for the phasediagram study. Classical methods of thermal analysis, like DTA and DSC are combined withmethods specifically developed for corium studies.The METCOR project (Investigation of Corium Melt Interaction with NPP ReactorVessel Steel) started in April 1999. The objectives of the project are to qualify and to quantifyphysico-chemical phenomena of corium melt interaction with reactor vessel steel cooled fromthe outside. The variable parameters of the interaction tests are: oxygen potential in thesystem, corium composition, interaction interface temperature and heat flux from corium tosteel. The medium scale tests with corium mass of about 2 kg are carried out by using highfrequency induction heating of the corium melt in a cold crucible.The METCOR & CORPHAD work-packages are performed by Russian partners inclose collaboration with leading European scientific institutes in the area of corium researchas well as with the European nuclear industry.This paper briefly describes the results obtained in both projects and their possibleapplication for SA analysis and SAM. The paper concludes with recommendations for futureresearch activities in the framework of METCOR and CORPHAD projects.
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| 5. |
- Bechta, Sevostian, et al.
(author)
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Experimental studies of oxidic molten corium-vessel steel interaction
- 2001
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In: Nuclear Engineering and Design. - 0029-5493 .- 1872-759X. ; 210:1-3, s. 193-224
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Journal article (peer-reviewed)abstract
- The experimental results of molten corium-steel specimen interaction with molten corium on the 'Rasplav-2' test facility are presented. In the experiments, cooled vessel steel specimens positioned on the molten pool bottom and uncooled ones lowered into the molten pool were tested. Interaction processes were studied for different corium compositions, melt superheating and in alternative (inert and air) overlying atmosphere. Hypotheses were put forward explaining the observed phenomena and interaction mechanisms. The studies presented in the paper were aimed at the detection of different corium-steel interaction mechanisms. Therefore certain identified phenomena are more typical of the ex-vessel localization conditions than of the in-vessel corium retention. Primarily, this can be referred to the phenomena of low-temperature molten corium-vessel steel interaction in oxidizing atmosphere.
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| 6. |
- Bechta, Sevostian, et al.
(author)
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Phase diagram of the UO2-FeO1+x system
- 2007
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In: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 362:1, s. 46-52
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Journal article (peer-reviewed)abstract
- Phase-relation studies of the UO2–FeO1+x system in an inert atmosphere are presented. The eutectic point has beendetermined, which corresponds to a temperature of (1335 ± 5) C and a UO2 concentration of (4.0 ± 0.1) mol.%. Themaximum solubility of FeO in UO2 at the eutectic temperature has been estimated as (17.0 ± 1.0) mol.%. Liquidus temperaturesfor a wide concentration range have been determined and a phase diagram of the system has been constructed.
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| 7. |
- Bechta, Sevostian, et al.
(author)
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Phase diagram of the ZrO2-FeO system
- 2006
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In: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 348:1-2, s. 114-121
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Journal article (peer-reviewed)abstract
- The results on the ZrO2–FeO system studies in a neutral atmosphere are presented. The refined eutectic point has beenfound to correspond to a ZrO2 concentration of 10.3 ± 0.6 mol% at 1332 ± 5 C. The ultimate solubility of iron oxide inzirconia has been determined in a broad temperature range, taking into account the ZrO2 polymorphism. A phase diagramof the pseudobinary system in question has been constructed.
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| 8. |
- Bechta, Sevostian, et al.
(author)
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Phase Relations in the ZrO2–FeO System
- 2006
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In: Russian Journal of Inorganic Chemistry. - 0036-0236 .- 1531-8613. ; 51:2, s. 325-331
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Journal article (peer-reviewed)abstract
- We present the results of the investigation of the ZrO2-FeO system under an inert atmosphere. We have refined the position of the eutectic point, which lies at 1332 +/- 5 degrees C and 10.3 +/- 0.6 mol % ZrO2. The iron oxide solubility boundaries in zirconium dioxide have been determined over a wide temperature range taking into account the polymorphism in ZrO2. A phase diagram for the system has been designed.
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| 9. |
- Bechta, Sevostian, et al.
(author)
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Phase transformation in the binary section of the UO2-FeO-Fe system
- 2007
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In: Radiochemistry (New York, N.Y.). - 1066-3622 .- 1608-3288. ; 49:1, s. 20-24
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Journal article (peer-reviewed)abstract
- Phase transformations in the oxide binary section of the UO2-FeO-Fe ternary system were studied. The melting onset point of the UO2-FeO heterogeneous system (1335±5°C) was determined and the fusion curve of this system was constructed. The limiting solubility of FeO in the UO2 solid solution was measured. The changes in crystal parameters in formation of the solid solution were determined. Uranium dioxide was found to be insoluble in the wüstite phase (FeO).
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| 10. |
- Udalov, Yu. P., et al.
(author)
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Monotectic Crystallization of Melts in the ZrO2–Al2O3 System
- 2006
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In: Glass Physics and Chemistry. - 1087-6596 .- 1608-313X. ; 32:4, s. 479-485
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Journal article (peer-reviewed)abstract
- —The morphology of the crystalline phases prepared at different cooling rates, temperatures, andcompositions of melts in the ZrO2–Al2O3system is investigated. It is established that both the quenched andslowly crystallized samples containing 35–70 wt % ZrO2have a submicron structure. Outside this concentrationrange, the ingots have a zonal structure: the peripheral region is formed by large baddeleyite crystals (at a ZrO2content higher than 70 wt %) or corundum crystals (at a ZrO2content lower than 30 wt %). This character ofthe crystallization confirms the presence of the phase separation (liquid immiscibility) region in melts of thissystem. A variant is proposed for the phase diagram of the system under investigation.
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