FLICA-OVAP: Elements of validation for LWRs thermal-hydraulic studies

FLICA-OVAP is an advanced two-phase flow thermal-hydraulics code based on a full 3-Dimensional subchannel approach. It is designed to analyze flows in Light Water Reactors (LWRs) cores such as PWRs, BWRs and experimental reactors. Therefore its applicability covers all ranges of operating conditions for water-cooled reactors. The FLICA-OVAP code includes several models, to adapt to the needs associated to different core concepts and multiple industrial and research applications. The set of models includes a Homogeneous Equilibrium Model (HEM), a four-equation drift flux model, a two-fluid model and a more general multi-field model. Several correlations are available to account for momentum, heat and mass transfer phenomena, as well as turbulence effects. This paper presents an overview of FLICA-OVAP modelling capabilities for applications in nuclear reactors design and safety analysis. A validation matrix is proposed and its results are presented. The matrix covers a wide range of selected phenomena, which are relevant for thermal-hydraulics studies. Therefore the different FLICA-OVAP physical correlations addressed in the current study include single phase and two-phase friction factors, single phase and boiling heat transfer, turbulence and critical heat flux. Results of the FLICA-OVAP validation studies highlight the capabilities of the code to well-predict two-phase flows in Light Water Reactors for both normal operation and under accidental circumstances. Future developments as well as validation activities are also summarized. (authors)