https://cea.hal.science/cea-02434036Prea, R.R.PreaCEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) - CEA - Commissariat à l'énergie atomique et aux énergies alternativesFigerou, V.V.FigerouCEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) - CEA - Commissariat à l'énergie atomique et aux énergies alternativesMekkas, A.A.MekkasCEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) - CEA - Commissariat à l'énergie atomique et aux énergies alternativesRuby, A.A.RubyCEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) - CEA - Commissariat à l'énergie atomique et aux énergies alternativesCATHARE-3: A first computation of a 3-inch break Loss-Of-Coolant Accident using both Cartesian and cylindrical 3D-meshes modeling of a PWR vesselHAL CCSD2017System codes3D-vesselNon-Conformal junctionsCATHARE-3LOCA[PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex][PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th]amplexor, amplexor2020-01-09 16:14:392023-09-21 03:03:282020-01-09 16:27:50enConference papersapplication/pdf1CATHARE-3 is the new version of the French thermal-hydraulic code for safety analysis of nuclearreactors. It is developed in the framework of the NEPTUNE project launched by the CEA, EDF, AREVANP and IRSN in 2001. CATHARE-3 V2.0 was delivered by December 2016.The paper will focus on a particular test-case, showing the new abilities of CATHARE-3. The PWR vesselhas been described using seven 3D-modules, with a Cartesian coordinate meshing for the core (with onecell per assembly in a horizontal section) and cylindrical coordinate meshing for the other vesselcomponents (downcomer, upper and lower plena …). Using this modeling, a 2,800s simulation of a 3-inchbreak Loss-Of-Coolant Accident (LOCA) in one of the PWR cold legs has been run and compared to resultswith a CATHARE-2 and CATHARE-3 “classical” modeling for the vessel (with only cylindrical grids).This computation has been made possible by the development of non-conformal junctions betweenCartesian coordinates and cylindrical coordinates. A similar computation is not possible with CATHARE2 because non-conformal junctions are not available. Many analytical verification test-cases of the nonconformal junctions have also been made, checking the mass-flow and energy-flow conservation at thenon-conformal junctions on various configurations. These test-cases, showing that an improvement formomentum equations is needed, are also presented in the paper.This 3D-vessel modeling also shows the abilities of CATHARE-3 to manage a large number of 3D-cells(about 7000 instead of less than 1000 for a typical CATHARE-2 3D-vessel modeling) thanks to the newnumerical methods available in CATHARE-3.This computation demonstrates the potential of CATHARE-3, which should reach the status of an industrialtool available for safety studies in 2019.