| 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. |
- Asmolov, V.G., et al.
(author)
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Crucible-type core catcher for VVER-1000 reactor
- 2005
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In: Proceedings of the American Nuclear Society - International Congress on Advances in Nuclear Power Plants 2005, ICAPP'05. - : Curran Associates, Inc.. - 9781604236934 ; , s. 1221-1227
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Conference paper (peer-reviewed)abstract
- For new designs of NPPs with VVER-1000 reactors a crucible-type core catcher has been developed to stabilize and cool down molten corium in the reactor pit. The paper addresses distinguishing features of the concept including the "sacrificial" material and the core catcher design. Main phenomena in the catcher have been analyzed.
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| 3. |
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| 4. |
- Bechta, Sevostian, et al.
(author)
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Corium phase equilibria based on MASCA, METCOR and CORPHAD results
- 2008
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In: Nuclear Engineering and Design. - : Elsevier BV. - 0029-5493 .- 1872-759X. ; 238:10, s. 2761-2771
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Journal article (peer-reviewed)abstract
- Experimental data on component partitioning between suboxidized corium melt and steel in the invessel melt retention (IVR) conditions are compared. The data are produced within the OECD MASCAprogram and the ISTC CORPHAD project under close-to-isothermal conditions and in the ISTC METCORproject under thermal gradient conditions. Chemical equilibrium in the U–Zr–Fe(Cr,Ni,. . .)–O system isreached in all experiments. In MASCA tests the molten pool formed under inert atmosphere has twoimmiscible liquids, oxygen-enriched (oxidic) and oxygen-depleted (metallic), resulting of the miscibilitygap of the mentioned system. Sub-system data of the U–Zr–Fe(Cr,Ni,. . .)–O phase diagram investigatedwithin the ISTC CORPHAD project are interpreted in relation with the MASCA results. In METCOR teststhe equilibrium is established between oxidic liquid and mushy metallic part of the system. Results ofcomparison are discussed and the implications for IVR noted.
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| 5. |
- 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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| 6. |
- Bechta, Sevostian, et al.
(author)
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Corrosion of vessel steel during its interaction with molten corium : Part 2. Model development
- 2006
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In: Nuclear Engineering and Design. - : Elsevier BV. - 0029-5493 .- 1872-759X. ; 236:13, s. 1362-1370
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Journal article (peer-reviewed)abstract
- An experimental examination of the cooled vessel steel corrosion during the interaction with molten corium is presented. The experiments havebeen conducted on “Rasplav-2” test facility and followed up with physico-chemical and metallographic analyses of melt samples and coriumspecimeningots. The results discussed in the first part of the paper have revealed specific corrosion mechanisms for air and inert atmosphere abovethe melt. Models have been proposed based on this information and approximate curves constructed for the estimation of the corrosion rate orcorrosion depth of vessel steel in conditions simulated by the experiments.
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| 7. |
- Bechta, Sevostian, et al.
(author)
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Corrosion of vessel steel during its interaction with molten corium : Part 1. Experimental
- 2006
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In: Nuclear Engineering and Design. - : Elsevier BV. - 0029-5493 .- 1872-759X. ; 236:17, s. 1810-1829
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Journal article (peer-reviewed)abstract
- This paper is concerned with corrosion of a cooled vessel steel structure interacting with molten corium in air and neutral (nitrogen) atmospheresduring an in-vessel retention scenario. The data on corrosion kinetics at different temperatures on the heated steel surface, heat flux densities andoxygen potential in the system are presented. The post-test physico-chemical and metallographic analyses of melt samples and the corium–specimeningot have clarified certain mechanisms of steel corrosion taking place during the in-vessel melt interaction.
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| 8. |
- Bechta, Sevostian, et al.
(author)
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Experimental study of interactions between suboxidized corium and reactor vessel steel
- 2006
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In: Proceedings of the 2006 International Congress on Advances in Nuclear Power Plants, ICAPP'06. - 0894486985 - 9780894486982 ; , s. 1355-1362
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Conference paper (peer-reviewed)abstract
- One of the critical factors in the analysis of in-vessel melt retention is the vessel strength. It is, in particular, sensitive to the thickness of intact vessel wall, which, in its turn, depends on the thermal conditions and physicochemical interactions with corium. Physicochemical interaction of prototypic UO2-ZrO2-Zr corium melt and VVER vessel steel was examined during the 2nd Phase of the ISTC METCOR Project. Rasplav-3 test facility was used for conducting four tests, in which the Zr oxidation degree and interaction front temperature were varied; in one of the tests, stainless steel was added to the melt. Direct experimental measurements and posttest analyses were used for determining corrosion kinetics and maximum corrosion depth (i.e. the physicochemical impact of corium on the cooled vessel steel specimens), as well as the steel temperature conditions during the interaction, and finally the structure and composition of crystallized ingots, including the interaction zone. The minimum temperature on the interaction front boundary, which determined its final position and maximum corrosion depth was ∼ 1090°C. An empirical correlation for calculation of corrosion kinetics has been derived.
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| 9. |
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| 10. |
- Bechta, Sevostian, et al.
(author)
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Interaction between molten corium UO2+X-ZrO2-FeO y and VVER vessel steel
- 2009
-
In: Proceeding of International Conference on Advances in Nuclear Power Plants, ICAPP 2008. - : Curran Associates, Inc.. - 9781605607870 ; , s. 210-218
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Conference paper (peer-reviewed)abstract
- In case of an in-vessel corium retention (1VR) the deterioration of vessel steel properties can be caused both by the steel melting and by its physicochemical interaction with corium. The interaction behavior has been studied in the medium-scale experiments with a prototypic corium within the METCOR project. The resulting experimental data give an insight into the steel corrosion during its interaction with U02+x- Zr02- FeOy melt in air and steam. It has been observed that the corrosion rate is almost the same in air and steam atmosphere; if the temperature on the interaction interface increases beyond a certain level, corrosion intensifies, which is explained by the formation of liquid phases in the interaction zone. The available experimental data have been used for developing a correlation of corrosion rate versus temperature and heat flux.
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| 11. |
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| 12. |
- Bechta, Sevostian, et al.
(author)
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Phase diagram of the UO2-FeO1+x system
- 2007
-
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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| 13. |
- Bechta, Sevostian, et al.
(author)
-
Phase diagram of the ZrO2-FeO system
- 2006
-
In: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 348:1-2, s. 114-121
-
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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| 14. |
- Bechta, Sevostian, et al.
(author)
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Phase Relations in the ZrO2–FeO System
- 2006
-
In: Russian Journal of Inorganic Chemistry. - 0036-0236 .- 1531-8613. ; 51:2, s. 325-331
-
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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| 15. |
- Bechta, Sevostian, et al.
(author)
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Phase transformation in the binary section of the UO2-FeO-Fe system
- 2007
-
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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| 16. |
- Bechta, Sevostian, et al.
(author)
-
VVER steel corrosion during in-vessel retention of corium melt
- 2008
-
In: Proceedings of the 3<sup>rd</sup> European Review Meeting on Severe Accident Research (ERMSAR 2008).
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Conference paper (peer-reviewed)abstract
- Physicochemical phenomena taking place at the corium-steel interaction during theexternal cooling of reactor vessel can result in high-temperature steel corrosion and thinningof the vessel wall. The ISTC METCOR project's experimental studies have shown that themain factors influencing corrosion depth and kinetics are oxygen potential, melt compositionand steel interfacial temperature but also melt – vessel heat flux.Experimental data are used for building a model for VVER vessel steel corrosion undercorium thermochemical loads and for correlations to quantitatively analyze the influence ofcorrosion on the rector vessel thinning. The finite-element calculations, in which thedeveloped models of corrosion and heat transfer in corium pool were used, were able toreproduce the temperature and stress-and-strain vessel condition.
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| 17. |
- Bechta, Sevostian, et al.
(author)
-
VVER vessel steel corrosion at interaction with molten corium in oxidizing atmosphere
- 2009
-
In: Nuclear Engineering and Design. - : Elsevier BV. - 0029-5493 .- 1872-759X. ; 239:6, s. 1103-1112
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Journal article (peer-reviewed)abstract
- The long-term in-vessel corium retention (IVR) in the lower head bears a risk of the vessel wall deterioration caused by steel corrosion. The ISTC METCOR Project has studied physicochemical impact of prototypic coria having different compositions in air and steam and has generated valuable experimental data on vessel steel corrosion. It is found that the corrosion rate is sensitive to corium composition, but the composition of oxidizing above-melt atmosphere (air, steam) has practically no influence on it. A model of the corrosion process that integrates the experimental data, is proposed and used for development of correlations.
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| 18. |
- Gusarov, V.V., et al.
(author)
-
Distribution of components between immiscible melts of a system under nonisothermal conditions
- 2006
-
In: Glass Physics and Chemistry. - 1087-6596 .- 1608-313X. ; 32:6, s. 638-642
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Journal article (peer-reviewed)abstract
- The influence of the temperature difference at the interface on the redistribution of components between coexisting liquid phase is analyzed using the U-Zr-O system as an example. It is demonstrated that, in this system, there can arise new dynamic effects in boundary regions of the coexisting phases. These effects are of considerable practical importance, for example, for the prediction of the behavior of the system in severe accidents at nuclear power plants.
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| 19. |
- Gusarov, V.V., et al.
(author)
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Interaction of a material based on aluminum and iron oxides with a metal melt
- 2007
-
In: Russian journal of applied chemistry. - 1070-4272 .- 1608-3296. ; 80:4, s. 528-535
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Journal article (peer-reviewed)abstract
- Interaction of an oxide material with a melt of metals in the combustion mode was studied experimentally. The conditions in which processes of this kind can occur without any increase in the temperatureof the environment are possible were analyzed.
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| 20. |
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| 21. |
- Gusarov, V.V., et al.
(author)
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Physicochemical Modeling and Analysis of the Interaction between a Core Melt of the Nuclear Reactor and a Sacrificial Material
- 2005
-
In: Glass Physics and Chemistry. - : Springer Science and Business Media LLC. - 1087-6596 .- 1608-313X. ; 31:1, s. 53-66
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Journal article (peer-reviewed)abstract
- -The problems regarding the design of a new class of materials, namely, sacrificial materials for usein devices intended for localization of a core melt of the nuclear reactor, are considered. Criteria are proposedfor the proper choice of the chemical composition of a sacrificial material, as well as of the composition andmicrostructure of its constituents. The possible alternatives are outlined and analyzed. The results of designinga variant of the composition of sacrificial materials are presented. The experimental data on the interaction ofan oxide sacrificial material with simulators of the metal and oxide phases of the core melt are discussed. A newtype of combustion of materials, namely, the liquid-phase combustion, is revealed. It is demonstrated that thematerial designed can be used in systems intended for localization of a core melt of the nuclear reactor.
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| 22. |
- Gusarov, V.V., et al.
(author)
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Physicochemical simulation of the combustion of materials with the total endothermal effect
- 2007
-
In: Glass Physics and Chemistry. - 1087-6596 .- 1608-313X. ; 33:5, s. 492-497
-
Journal article (peer-reviewed)abstract
- A new type of combustion, namely, the combustion of materials without heating of the environment, is described, and the conditions under which this process can occur are analyzed. It is demonstrated that the possibility of occurring the process under consideration depends substantially on the microstructure of the material. The characteristics of the material for which the liquid-phase combustion takes place without an increase in the temperature of the melt are determined using the interaction of a material based on iron and aluminum oxides with the Fe-Zr-O melt as an example.
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| 23. |
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| 24. |
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| 25. |
- Khabensky, V.B., et al.
(author)
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Severe accident management concept of the VVER-1000 and the justification of corium retention in a crucible-type core catcher
- 2009
-
In: Nuclear Engineering and Technology. - 1738-5733. ; 41:5, s. 561-574
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Journal article (peer-reviewed)abstract
- First ex-vessel core catcher has been applied to the practical design of NPPs with VVER-1000 reactors built in China(Tyanvan) and India (Kudankulam) for severe accident management (SAM) and mitigation of SA consequences. The paperpresents the concept and basic design of this crucible-type core catcher as well as an evaluation of its efficiency. Theimportant role of oxidic sacrificial material is discussed. Insight into the behaviour of the molten pool, which forms in thecatcher after core relocation from the reactor vessel, is provided. It is shown that heat loads on the water-cooled vessel wallsare kept within acceptable limits and that the necessary margins for departure from nucleate boiling (DNB) and of vesselfailure caused by thermo-mechanical stress are satisfactorily provided for.
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| 26. |
- Mezentseva, L.P., et al.
(author)
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Phase and chemical transformations in the SiO2-Fe2O3(Fe3O4) system at various oxygen partial pressures
- 2006
-
In: Russian Journal of Inorganic Chemistry. - 0036-0236 .- 1531-8613. ; 51:1, s. 118-125
-
Journal article (peer-reviewed)abstract
- The SiO2-Fe2O3(F3O4) system has been studied in air, oxygen, and an inert atmosphere. The dissociation temperatures for iron oxides, the onset and full melting temperatures for coexisting phases, and the melt demixing temperatures have been determined as a function of the oxygen partial pressure. A scenario of the phase and chemical transformations in the title systems has been developed.
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| 27. |
- Sulatsky, A.A., et al.
(author)
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Molten corium interaction with oxidic sacrificial material of WER core catcher
- 2005
-
In: Proceedings of the American Nuclear Society. - 9781604236934 ; , s. 1238-1246
-
Conference paper (peer-reviewed)abstract
- The results of experimental studies on the interaction between the oxidic corium melt containing unoxidized zirconium and sacrificial materials of the VVER core catcher are presented. The phenomena of suboxidized corium interaction with sacrificial material have been determined and appropriate model has been developed.
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| 28. |
- Vasilenko, V.A., et al.
(author)
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NITI severe accident research under ISTC coordination
- 2009
-
In: Proceedings of FISA 2009, Seventh European Commission conference on Euratom research and training in reactor systems. - 9789279133022
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Conference paper (peer-reviewed)abstract
- From the very start of ISTC activities NITI has been involved in its projects on the conversion of industrial and engineering potential from military to civil needs and priorities. These projects include studies aimed at efficient severe accident management (SAM) and safety enhancement of commercial nuclear reactors. Detailed information on the projects is published in /1 - 11/.Most of the experimental studies have been carried out in the RASPLAV experimental platform, which:- Comprises 4 experimental facilities integrated into the shared infrastructure of auxiliary and protective systems. The experimental facilities are based on the principle of induction melting in a cold crucible (IMCC) at different heating frequencies;- Enables melting and various manipulations with chemically prototypic corium having mass up to8 kgand temperature up to 3200 С in different atmospheres (inert (Ar, He), oxidizing (steam, air), or their mixtures);- Is certified for work with unirradiated uranium and radiolabeled fission product simulants.In the EU countries results of these ISTC projects are used for reactor application particularly for optimization of NUCLEA - European thermodynamic database, development and implementation of different SAM concepts. Results delivered by the ISTC projects together with data of other projects carried out within national programs have an important reactor application inRussia, i.e.:- Jointly with SPbAEP ex-vessel SAM concept [12] has been developed, which foresees corium retention in the reactor cavity of Tyanvan NPP (China) and Kudankulam NPP (India) equipped by VVER-1000 reactors.- New oxidic sacrificial material [13] has been developed jointly with ISCh RAS and RSC KI. This material is a key component in the above-mentioned melt retention concept.- New crucible-type core catcher for VVER-1000 [14] has been developed and justified in collaboration with SPbAEP, RRC KI, IBRAE RAS, PKF of ROSENERGOATOM, ISCh RAS, SPbGETU, IPPE and SPb GTI (TU).- Concept of in-vessel corium retention has been justified for VVER-640 project based on the application of passive safety systems.The developed concept, ex-vessel catcher and innovative solutions are currently in use in the NPP-2006 projects with VVER-1200, which are under construction inRussia.Long-term and diverse experience in international projects coordinated by the ISTC generated fruitful cooperation on severe accident issues between NITI and European organizations. The following formats of cooperation can be mentioned:- Multi-lateral exchanges with European scientific research centers collaborating within the ISTC projects.- Multi-lateral cooperation coordinated by the OECD and RSC KI with the participants of MASCA program. NITI took part in preparing CORTRAN program proposal.- Bilateral cooperation within the ISTC partnership projects.- Bilateral cooperation with CEA coordinated by Rosatom.- Communication with SARNET, so far unilateral (SARNET members have an access to the ISTC project results through the CEG-SAM website).Short-term perspectives of a broader cooperation are related to the NITI’s initiative to participate in:- ROSATOM-EUROATOM program. In particular, a joint call on containment phenomena is under preparation for transnational use of large scale experimental facilities: MISTRA, CEA – PANDA, PSI – KMS, NITI- SARNET network of excellence, i.e. in the packages related to severe accident research.
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