3D SIMULATION OF A 500KG UO2 MELT IN A COLD CRUCIBLE INDUCTION FURNACE

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3D simulation of a 500kg UO2_2 melt in a cold crucible induction furnace

International audienceIn the field of severe accident studies for nuclear generation reactors 2, 3 and 4, the Plinius-2 project aims to build a new facility to perform experiments of corium interactions tests at a large scale until 2020. In this context, the project in collaboration with ECM Technology has to define and build a furnace able to melt up to 500 kg of simulated corium of various compositions (mix of UO$_2$ ,ZrO$_2$ , steel or concrete). The work presented in this article is a 3D dimensional simulation of a large load of UO$_2$ melts in a cold crucible, including turbulence modelling, induction heating and stirring. Solidification of the oxide near the cold wall of the crucible is taken into account as well as the heat radiation transfer at the free surface. Introduction. The cold crucible technology has been selected in this project because it has already proven his ability to melt corium thanks to Korean [1, 2] and Russian [3, 4] works but only for lower mass. Simulation of such induction furnace is quite well known in the CEA Marcoule for vitrifiction purposes [5, 6]. But the simulation has to be upgraded to take into account LES turbulence modelling and Lorentz forces which were both neglected for glass simulations due to its very high viscosity and low electrical conductivity. Recent work [7] demonstrates the feasibility of similar simulation using a LES turbulence model with a very good accuracy

UO2_2-ZrO2_2 melting in a cold crucible induction furnace : simulation and experiments

International audienceIn the field of severe accident studies for generation 2, 3 & 4 nuclear reactors, thePlinius-2 project aims to build a new facility to perform experiments of coriuminteractions tests at a large scale until 2020. In this context, the project, incollaboration with ECM Technologies, has to define and build a furnace able to melt upto 500 kg of different compositions of corium surrogate

UO2 ZrO2 melting in a cold crucible induction furnace simulation and experimentsUO2 ZrO2 melting in a cold crucible induction furnace simulation and experiments

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Presentation of the CETAMA working group 21

International audienceCETAMA network is organized in 13 thematic working groups. The working group number 21 is dedicated to Electron Probe Micro Analysis (EPMA). Its main mission is to listen to participant needs about EPMA practical issues and to propose tools in order to improve the quality of measurement and analysis results

CETAMA Contribution to Safeguards and Nuclear Forensic Analysis based on Nuclear Reference Materials

AbstractMeasurement quality is crucial for the safety of nuclear facilities: nuclear reference materials (CRM) and interlaboratory programs (ILC), beyond the assessment of analytical measurement quality, play an important role. In the nuclear field, the CETAMA proposes suitable scientific and technical developments, in particular the preparation and certification of CRM used either as analytical standards or as reference samples for ILCs. The growing emphasis on nuclear forensic measurements will require some re-certification of old CRMs. But the future analytical challenges of meeting nuclear fuel cycle needs and of ensuring safeguard performance improvements will also concern the future CRMs

Plinius-2 a new corium facility and programs to support the safety demonstration of the astrid mitigation provisions under severe accident conditions

International audienceThe ASTRID reactor (Advanced Sodium Technological Reactor for Industrial Demonstration) is a technological demonstrator of sodium-cooled fast reactor (SFR) designed by the CEA with its industrial partners, with very high levels of requirements. Innovative options have been integrated to enhance the safety, to reduce the capital cost and improve the efficiency, reliability and operability, making the Generation IV SFR an attractive option for electricity production. In the ASTRID project, the safety objectives are first to prevent the core melting, in particular by the development of an innovative core (named CFV core) with heterogeneous pins and complementary safety prevention devices, and second, to enhance the reactor resistance to severe accident by design. In order to mitigate the consequences of hypothetical core melting situations, specific dispositions or mitigation devices are added to the core and to the reactor some corium Transfer Tubes are implemented, allowing molten corium discharge outside the core region toward a core catcher which insures sub-criticality, cooling and confinement of the relocated materials.For a robust safety demonstration, CEA with its partners is improving or developing codes (SIMMER, SCONE and EUROPLEXUS) to simulate de Severe Accidents progression. These codes must be assessed, and the mitigation devices qualified against experiments. Since no facility is worldwide available allowing tests with Sodium and large masses of prototypic corium (about 500kg) to study corium discharge through full-scale Corium Transfer Tube, Fuel-Sodium-Interactions and subsequent Sodium vapor explosion, and Corium Interactions with the sacrificial material which protects the Core-Catcher tray, CEA has decided to build a new versatile facility, called PLINIUS-2; this new experimental platform will extend the PLINIUS capabilities where the handled corium mass was limited to 50kg of UO2, and only Fuel-Water-Interaction where studied. After describing the ASTRID design options related to Severe Accidents and the main features of the PLINIUS-2, the paper will describe the analytical and global experimental programs planned in PLINIUS-2, supporting the ASTRID development; the used molten mass of UO2 will range from few grams to 500kg. The programs will be devoted to the study of Fuel-Sodium Interactions (Droplet fragmentation, Corium Jet Fragmentation, Sodium Vapor Explosion), of Corium-Sacrificial Material Interactions (corium jet impingement, long term sacrificial material ablation by the corium), and to the qualification of the corium Transfer Tubes

Analysis of Pu by Virtual-standard WDS-EPMA. Results of an Interlaboratory Round-robin Test

The understanding of the behaviour of nuclear fuels under different operating conditions requires accurate wavelength-dispersive electron-probe microanalysis (WDS-EPMA) of materials that contain actinide elements. Conventional WDS-EPMA is based on the measurement of k-ratios, i.e. the ratio of the x-ray intensity emitted by the element of interest in the unknown to that emitted by the same element in a reference standard. The advantage of using such approach is that several instrumental, spectroscopic and atomic parameters that are generally poorly known cancel out from the quantification equations and are no longer required. Moreover, the effect of the approximations adopted to describe quantities such as the depth-distribution of ionizations or the cross section for inner-shell ionization is largely reduced. As a result, the accuracy of concentrations obtained by WDS-EPMA using reference standards can be as good as 2%, even when x-ray attenuation effects are important. However, for some actinide elements such as Plutonium (Pu) or Americium (Am), reference standards are difficult to obtain. In these situations, the use of standardless methods of analysis [1,2], which use calculated intensities to replace measurements on the standards, would be an ideal alternative. However, the accuracy of such methods is limited by the poor knowledge of the different instrumental, spectroscopic and atomic parameters required, as mentioned above. Significant benefits would be gained if measurements on standards could be transferred among different WDS instruments; this would allow the creation of a set of ¿virtual standards¿ which could be shared among different laboratories. The use of virtual standards requires accurate knowledge of instrumental parameters (e.g. the spectrometer efficiency and solid angle of detection) and spectroscopic parameters (e.g. the line shape), but knowledge of atomic parameters is not required. This is important for the actinide elements, which involve the measurement of M xrays, where atomic parameters such as the fluorescence yield, the Coster-Kronig and super-Coster-Kronig transition probabilities or the cross section for M-subshell ionization are affected by large uncertainties (>30%).JRC.E.2-Hot cell

Analysis of Pu by Virtual-standard WDS-EPMA. Results of an interlaboratory round-robin test for wavelength-dispersive electron-probe microanalysis

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