Validation physique du modèle Neptune diphasique : plan de validation à adopter, programmes expérimentaux à installer et techniques associées d'instrumentation développées

Abstract

The NEPTUNE Project constitutes the Thermal-Hydraulics part of a long-term joint development program for the next generation of nuclear reactors simulation tools. The physical validation of the involved modelling embedded in this new two-phase flow software platform is a crucial issue. After explaining the general validation strategy to be adopted, a four-step generic work approach has been defined; it includes: (i) a thorough analysis of the concerned industrial applications to identify the key physical phenomena involved and associated dominant basic models, (ii) an assessment of these models against the available validation pieces of information, to specify the additional validation needs and define dedicated validation plans, (iii) an inventory and assessment of existing validation data (with respect to the requirements specified in the previous step) to identify the actual needs for new validation data, (iv) the specification of the new experimental programs to be set up to provide the needed new data. This work approach has resulted in the definition of (i) the validation plan and experimental programs to be set up for the open medium 3D CFD modelling, successively in close connection with the in-PWR core DNB and PTS applications, and (ii) high priority experimental programs, with respect to porous medium multi-field and interfacial area transport, in connection with LB-LOCA application. These experimental programs will require the use of specific instrumentation to provide local characteristics of both liquid and vapor phases, such as local void fraction, local interfacial area concentration and local liquid velocity. To fulfill these needs, some measurement techniques have been developed/enhanced and assessed.