| 1. |
- Journeau, C., et al.
(author)
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European Research on the Corium issues within the SARNET network of excellence
- 2008
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In: International Conference on Advances in Nuclear Power Plants, ICAPP 2008. - 9781605607870 ; , s. 1172-1181
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Conference paper (peer-reviewed)abstract
- Within SARNET, the corium topic covers all the behaviors of corium from early phase of core degradation to in or ex-vessel corium recovery with the exception of corium interaction with water, direct containment heating and fission product release. The corium topic regroups in three work packages the critical mass of competence required to improve significantly the corium behavior knowledge. The spirit of the SARNET networking is to share the knowledge, the facilities and the simulation tools for severe accidents, so to reach a better efficiency and to rationalize the R&D effort at European level. Extensive benchmarking has been launched in most of the areas of research. These benchmarks were mainly dedicated to the recalculation of experiments, while, in the next periods, a larger focus will be given to integral experiments or reactor applications. Eventually, all the knowledge will be accumulated in the ASTEC severe accident simulation code through physical model improvements and extension of validation database. This paper summarizes the progress that has been achieved in the frame of the networking activities. A special focus is placed on the melt pool and debris coolability and corium-concrete interaction, in which, the effects due to multidimensional geometries and heterogeneities has been shown, during SARNET, to play a crucial role and for which further research is still needed.
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| 2. |
- Bakardjieva, S., et al.
(author)
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Improvement of the European thermodynamic database NUCLEA
- 2010
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In: Progress in nuclear energy (New series). - : Elsevier BV. - 0149-1970 .- 1878-4224. ; 52:1, s. 84-96
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Journal article (peer-reviewed)abstract
- Modelling of corium behaviour during a severe accident requires knowledge of the phases present at equilibrium for a given corium composition, temperature and pressure. The thermodynamic database NUCLEA in combination with a Gibbs Energy minimizer is the European reference tool to achieve this goal. This database has been improved thanks to the analysis of bibliographical data and to EU-funded experiments performed within the SARNET network, PLINIUS as well as the ISTC CORPHAD and EVAN projects. To assess the uncertainty range associated with Energy Dispersive X-ray analyses, a round-robin exercise has been launched in which a UO2-containing corium-concrete interaction sample from VULCANO has been analyzed by three European laboratories with satisfactorily small differences.
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| 3. |
- Bakardjieva, S., et al.
(author)
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Improvement of the European thermodynamic database NUCLEA in the frame of EU-funded experiments
- 2008
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In: Proceedings of the 3<sup>rd</sup> European Review Meeting on Severe Accident Research (ERMSAR 2008).
-
Conference paper (peer-reviewed)abstract
- Modelling of corium behaviour during a severe accident requires knowledge of the phases present at equilibrium for a given corium composition, temperature and pressure. The thermodynamic database NUCLEA in combination with a Gibbs Energy minimizer is theEuropean reference tool to achieve this goal. Within SARNET, this database has beenimproved thanks to the analysis of bibliographical data and to EU0funded experimentsperformed within the SARNET network, PLINIUS as well as the ISTC CORPHAD and EVAN projects. To assess the uncertainty range associated with Energy Dispersive X-ray analyses, a round robin exercise has been launched in which a UO2-containing coriumconcrete interaction sample from VULCANO has been analyzed by three European laboratories with satisfactorily small differences.
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| 4. |
- Bakardjieva, S., et al.
(author)
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Quality improvements of thermodynamic data applied to corium interactions for severe accident modelling in SARNET2
- 2014
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In: Annals of Nuclear Energy. - : Elsevier. - 0306-4549 .- 1873-2100. ; 74, s. 110-124
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Journal article (peer-reviewed)abstract
- In a severe accident transient, corium composition and its properties determine its behaviour and its potential interactions both with the reactor vessel and in the later phases with the concrete basemat. This, in turn, requires a detailed knowledge of the phases present at temperature and how they are formed. Because it implies mainly the investigation of chemical systems at high temperature, these data are often difficult to obtain or are uncertain if it already exists. Therefore more data are required both to complete the thermodynamic databanks (such as NUCLEA) and to construct accurate equilibrium phase diagrams and to finally contribute to the improvement of the codes simulating these severe accident conditions. The MCCI work package (WP6) of the SARNET 2 Network of Excellence has been addressing these problems. In this framework in large facilities such as VULCANO tests have been performed on the interactions and ablation of UO2-containing melts with concrete. They have been completed by large scale MCCI testing such EPICOR on vessel steel corrosion. In parallel in major EU-funded ISTC projects co-ordinated with national institutes, such as the CORPHAD and PRECOS, smaller, single effect tests have been carried out on the more difficult phase diagrams. These have produced data that can be directly used by databanks and for modelling improvement/validation. From these data significant advances in the melt chemistry and pool behaviour have been made. A selection of experiments from participating institutes are presented in this paper and give hindsight into the major processes and so give clear indications for the future work, especially in light of the Fukushima accident.
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| 5. |
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| 6. |
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| 7. |
- Yang, H., et al.
(author)
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Reductive precipitation of neptunium on iron surfaces under anaerobic conditions
- 2017
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In: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 496, s. 109-116
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Journal article (peer-reviewed)abstract
- Reductive precipitation of the radiotoxic nuclide Np-237 from nuclear waste on the surface of iron canister material at simulated deep repository conditions was investigated. Pristine polished as well as pre corroded iron specimens were interacted in a deoxygenated solution containing 10-100 mu M Np(V), with 10 mM NaCl and 2 mM NaHCO3 as background electrolytes. The reactivity of each of the two different systems was investigated by analyzing the temporal evolution of the Np concentration in the reservoir. It was observed that pre-oxidized iron specimen with a 40 tm Fe3O4 corrosion layer are considerably more reactive regarding the reduction and immobilization of aqueous Np(V) as compared to pristine polished FeM surfaces. Np-237 immobilized by the reactive iron surfaces was characterized by scanning electron microscopy as well as synchrotron-based micro-X-ray fluorescence and X-ray absorption spectroscopy. At the end of experiments, a 5-8 tm thick Np-rich layer was observed to be formed ontop of the Fe3O4 corrosion layer on the iron specimen. The findings from this work are significant in the context of performance assessments of deep geologic repositories using iron as high level radioactive waste (HLW) canister material and are of relevance regarding removing pollutants from contaminated soil or groundwater aquifer systems.
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