| 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. |
- Journeau, C., et al.
(author)
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Safest roadmap for corium experimental research in Europe
- 2018
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In: ASCE-ASME J of Risk & Uncertainty in Engineering Systems Part B. - : ASME Press. - 2332-9017 .- 2332-9025. ; 4:3
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Journal article (peer-reviewed)abstract
- Severe accident facilities for European safety targets (SAFEST) is a European project networking the European experimental laboratories focused on the investigation of a nuclear power plant (NPP) severe accident (SA) with reactor core melting and formation of hazardous material system known as corium. The main objective of the project is to establish coordinated activities, enabling the development of a common vision and severe accident research roadmaps for the next years, and of the management structure to achieve these goals. In this frame, a European roadmap on severe accident experimental research has been developed to define research challenges to contribute to further reinforcement of Gen II and III NPP safety. The roadmap takes into account different SA phenomena and issues identified and prioritized in the analyses of severe accidents at commercial NPPs and in the results of the recent European stress tests carried out after the Fukushima accident. Nineteen relevant issues related to reactor core meltdown accidents have been selected during these efforts. These issues have been compared to a survey of the European SA research experimental facilities and corium analysis laboratories. Finally, the coherence between European infrastructures and R&D needs has been assessed and a table linking issues and infrastructures has been derived. The comparison shows certain important lacks in SA research infrastructures in Europe, especially in the domains of core late reflooding impact on source term, reactor pressure vessel failure and molten core release modes, spent fuel pool (SFP) accidents, as well as the need for a large-scale experimental facility operating with up to 500 kg of chemically prototypic corium melt.
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| 3. |
- Alsmeyer, H, et al.
(author)
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Ex-vessel core melt stabilization research (ECOSTAR)
- 2005
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In: Nuclear Engineering and Design. - : Elsevier BV. - 0029-5493 .- 1872-759X. ; 235:2-4, s. 271-284
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Journal article (peer-reviewed)abstract
- The project on ex-vessel core melt stabilization research (ECOSTAR) started in January 2000 to be concluded by end of 2003. The project is performed by 14 partner institutions from five European countries and involves a large number of experiments with low- and high-temperature simulant melts and real corium at different scales. Model development and scaling analysis allows application of the research results to existing and to future LWRs in the area of reactor design and accident mitigation. The project is oriented toward the analysis and mitigation of severe accident sequences that could occur in the ex-vessel phase of a postulated core melt accident. The issues are: (1) the release of melt form the pressure vessel, (2) the transfer and spreading of the melt on the basement, (3) the analysis of the physical-chemical processes that are important for corium behavior especially during concrete erosion with onset of solidification, and (4) stabilization of the melt by cooling through direct water contact. The results achieved so far resolve a number of important issues: the amount of melt that could be transferred at RPV failure from the RPV into the containment can be substantially reduced by lowering the residual pressure in the primary circuit. It is found that melt dispersion also strongly depends on the location of the RPV failure, and that lateral failure results in substantially less melt dispersion. During melt release, the impinging melt jet could erode parts of the upper basement surface. Jet experiments and a derived heat transfer relation allow estimation of its contribution to concrete erosion. Spreading of the corium melt on the available basement surface is an important process, which defines the initial conditions for concrete attack or for the efficiency of cooling in case of water contact, respectively. Validation of the spreading codes based on a large-scale benchmark experiment is underway and will allow determination of the initial conditions, for which a corium melt can be assumed to spread homogeneously over the available surface. Experiments with UO(2)-based corium melts highlight the role of phase segregation during onset of melt solidification and during concrete erosion. To cool the spread corium melt, the efficacy of top flooding and bottom flooding is investigated in small-scale and in large-scale experiments, supported by model developments. Project assessment is continuing to apply the results to present and future reactors.
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| 4. |
- 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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| 5. |
- 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).
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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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| 6. |
- 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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| 7. |
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| 8. |
- Bechta, Sevostian, et al.
(author)
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Influence of corium oxidation on fission product release from molten pool
- 2010
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In: Nuclear Engineering and Design. - : Elsevier BV. - 0029-5493 .- 1872-759X. ; 240:5, s. 1229-1241
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Journal article (peer-reviewed)abstract
- Qualitative and quantitative determination of the release of low-volatile fission products and core materialsfrom molten oxidic corium was investigated in the EVAN project under the auspices of ISTC. Theexperiments carried out in a cold crucible with induction heating and RASPLAV test facility are described.The results are discussed in terms of reactor application; in particular, pool configuration, melt oxidationkinetics, critical influence of melt surface temperature and oxidation index on the fission productrelease rate, aerosol particle composition and size distribution. The relevance of measured high releaseof Sr from the molten pool for the reactor application is highlighted. Comparisons of the experimentaldata with those from the COLIMA CA-U3 test and the VERCORS tests, as well as with predictions fromIVTANTHERMO and GEMINI/NUCLEA codes are made. Recommendations for further investigations areproposed following the major observations and discussions.
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| 9. |
- Bottomley, D., et al.
(author)
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Severe accident research in the core degradation area : An example of effective international cooperation between the European Union (EU) and the Commonwealth of Independent States (CIS) by the International Science and Technology Center
- 2012
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In: Nuclear Engineering and Design. - : Elsevier BV. - 0029-5493 .- 1872-759X. ; 252, s. 226-241
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Journal article (peer-reviewed)abstract
- The International Science and Technology Center (ISTC) was set up in Moscow to support non-proliferation of sensitive knowledge and technologies in biological, chemical and nuclear domains by engaging scientists in peaceful research programmes with a broad international cooperation. The paper has two following objectives: to describe the organization of complex, international, experimental and analytical research of material processes under extreme conditions similar to those of severe accidents in nuclear reactors and, to inform briefly about some results of these studies. The main forms of ISTC activity are Research Projects and Supporting Programs. In the Research Projects informal contact expert groups (CEGs) were set up by ISTC to improve coordination between adjacent projects and to encourage international collaboration. The European Commission was the first to use this. The CEG members - experts from the national institutes and industry - evaluated and managed the projects' scientific results from initial stage of proposal formulation until the final reporting. They were often involved directly in the project's details by joining the Steering Committees of the project. The Contact Expert Group for Severe Accidents and Management (CEG-SAM) is one of these groups, five project groups from this area from the total of 30 funded projects during 10 years of activity are detailed to demonstrate this: (1) QUENCH-VVER from RIAR, Dimitrovgrad and IBRAE, Moscow, and PARAMETER projects (SF1-SF4) from LUCH, Podolsk and IBRAE, Moscow; these concerned a detailed study of bundle quenching from high temperature; (2) Reactor Core Degradation; a modelling project simulating the fuel rod degradation and loss of geometry from IBRAE, Moscow; (3) METCOR projects from NITI, St. Petersburg on the interaction of core melt with reactor vessel steel; (4) INVECOR project, NNE Kurchatov City, Kazakhstan; this is a large-scale facility to examine the vessel steel retention of 60 kg corium during the decay heat; and finally, (5) CORPHAD and PRECOS projects, NITI, St. Petersburg undertook a systematic examination of refractory ceramics relevant to in-vessel and ex-vessel coria, particularly examining poorly characterised, limited data or experimentally difficult systems.
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| 10. |
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| 11. |
- Klein-Hessling, W., et al.
(author)
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Conclusions on severe accident research priorities
- 2014
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In: Annals of Nuclear Energy. - : Elsevier BV. - 0306-4549 .- 1873-2100. ; 74, s. 4-11
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Journal article (peer-reviewed)abstract
- The objectives of the SARNET network of excellence are to define and work on common research programs in the field of severe accidents in Gen. II-III nuclear power plants and to further develop common tools and methodologies for safety assessment in this area. In order to ensure that the research conducted on severe accidents is efficient and well-focused, it is necessary to periodically evaluate and rank the priorities of research. This was done at the end of 2008 by the Severe Accident Research Priority (SARP) group at the end of the SARNET project of the 6th Framework Programme of European Commission (FP6). This group has updated this work in the FP7 SARNET2 project by accounting for the recent experimental results, the remaining safety issues as e.g. highlighted by Level 2 PSA national studies and the results of the recent ASAMPSA2 FP7 project. These evaluation activities were conducted in close relation with the work performed under the auspices of international organizations like OECD or IAEA. The Fukushima-Daiichi severe accidents, which occurred while SARNET2 was running, had some effects on the prioritization and definition of new research topics. Although significant progress has been gained and simulation models (e.g. the ASTEC integral code, jointly developed by IRSN and GRS) were improved, leading to an increased confidence in the predictive capabilities for assessing the success potential of countermeasures and/or mitigation measures, most of the selected research topics in 2008 are still of high priority. But the Fukushima-Daiichi accidents underlined that research efforts had to focus still more to improve severe accident management efficiency.
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| 12. |
- Mlassoedov, A., et al.
(author)
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Severe accident facilities for European safety targets : The safest project
- 2015
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In: International Topical Meeting on Nuclear Reactor Thermal Hydraulics 2015, NURETH 2015. - : American Nuclear Society. - 9781510811843 ; , s. 4604-4616
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Conference paper (peer-reviewed)abstract
- Severe accident with core meltdown is a threat to the containment integrity. As Chernobyl and Fukushima accidents demonstrate, significant release of radioactive products into the environment can have severe consequences both for people's health and the country's economy. Severe accidents arc the focus of considerable research involving substantial human and financial resources worldwide. The research field encompasses many challenging phenomena, complicated by high temperatures and presence of radioactive materials. No individual country has sufficient resources to address all important phenomena within the framework of a national research programme, therefore optimised use of resources and the collaboration at European and international level is very important. One of the mam objectives of the SAFEST project of the 7th EU framework programme is integrating European severe accident research facilities into a pan-European laboratory for study of corium behaviour in severe accidents The resources of this laboratory will be provided to other interested European partners for better understanding of possible accident scenarios and phenomena in order to improve safety of existing and. in the long-term, of future reactors. The SAFEST consortium will be able to address several severe accident issues related to accident analysis and corium behaviour. It will be a valuable asset for the fulfilment of the severe accident R&D programmes that arc being set up after Fukushima and the subsequent European stress tests, addressing both national and European objectives.
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| 13. |
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| 14. |
- Van Dorsselaere, J. -P, et al.
(author)
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Status of the SARNET network on severe accidents
- 2010
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In: International Congress on Advances in Nuclear Power Plants 2010, ICAPP 2010. - 9781617386435 ; , s. 1029-1043
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Conference paper (peer-reviewed)abstract
- After four and a half years of operation in the frame of the 6th Framework Programme (FP6) of the European Commission, SARNET (Severe Accidents Research NETwork of excellence) continues in the FP7 (project named SARNET2) from April 2009 for 4 years. Forty-one organisations from 21 countries network their capacities of research in order to resolve the most important remaining uncertainties and safety issues on severe accidents (SA) in existing and future water-cooled nuclear power plants (NPPs). It includes a large majority of the Europeanactors involved in SA research plus a few non-European important ones. The objective is to perform the common research programmes that have been defined in the network first phase and to continue to improve the common computer tools and methodologies for NPP safety assessment. It will consolidate the sustainable integration of the European SA research capacities. These research programmes concern essentially the six highest priority safety issues that were identified after ranking in the first phase of the network: in-vessel core coolability, molten-corium-concrete-interaction, fuel-coolant interaction, hydrogen mixing and combustion in containment, impact of oxidising conditions on source term, and iodine chemistry. The Joint Programme of Activities includes the following main tasks: Performing new experiments on the above mentioned issues andjointly analysing their results in order to elaborate a common understanding of the concerned physical phenomena; Continuing the development and assessment of the ASTEC integral computer code (jointly developed by IRSN and GRS to predict the NPP behaviour during a postulated SA), which capitalizes in terms of models the knowledge produced in the network. In particular efforts are being extended to its applicability to BWR and CANDU NPP types; Continuing the storage of the SA experimental results in a scientific database, based on the STRESA JRC tool; Promoting educational and training courses, ERMSAR (European Review Meeting on Severe Accident Research) international conferences (to be held once a year) and mobility of young researchers or students between the various European organisations. Some R&D results obtained in the first year of the project are presented, in particular: the VULCANO experiment done in CEA mid-2009 on molten-core-corium-interaction, and the release of the first version of the new ASTEC V2 series.
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| 15. |
- Van Dorsselaere, J. -P, et al.
(author)
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Sustainable integration of EU research in severe accident phenomenology and management
- 2011
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In: Nuclear Engineering and Design. - : Elsevier BV. - 0029-5493. ; 241:9, s. 3451-3460
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Journal article (peer-reviewed)abstract
- In order to optimise the use of the available means and to constitute sustainable research groups in the European Union, the Severe Accident Research NETwork of Excellence (SARNET) has gathered, between 2004 and 2008, 51 organizations representing most of the actors involved in severe accident (SA) research in Europe plus Canada. This project was co-funded by the European Commission (EC) under the 6th Euratom Framework Programme. Its objective was to resolve the most important pending issues for enhancing, in regard of SA, the safety of existing and future nuclear power plants (NPPs). SARNET tackled the fragmentation that existed between the national R&D programmes, in defining common research programmes and developing common computer codes and methodologies for safety assessment. The Joint Programme of Activities consisted in:Implementing an advanced communication tool for accessing all project information, fostering exchange of information, and managing documents;Harmonizing and re-orienting the research programmes, and defining new ones;Analyzing the experimental results provided by research programmes in order to elaborate a common understanding of relevant phenomena;Developing the ASTEC code (integral computer code used to predict the NPP behaviour during a postulated SA) by capitalizing in terms of physical models the knowledge produced within SARNET;Developing scientific databases, in which the results of research experimental programmes are stored in a common format;Developing a common methodology for probabilistic safety assessment of NPPs;Developing short courses and writing a text book on severe accidents for students and researchers;Promoting personnel mobility amongst various European organizations. This paper presents the major achievements after four and a half years of operation of the network, in terms of knowledge gained, of improvements of the ASTEC reference code, of dissemination of results and of integration of the research programmes conducted by the various partners. Most initial objectives were reached but the continuation of the SARNET network, co-funded by EC in the 7th Framework Programme (SARNET2 project that started in April 2009 for 4 years), will consolidate the first assets and focus mainly on the highest priority pending issues as determined during the first period. The objective will be also to make the network evolve towards a complete self-sustainability.
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