Assessment of stratification and entrainment models in CATHARE 3 code during FONESYS activities

• DOI: 10.1016/j.nucengdes.2024.113700
• Publication Date: 2024-11-17T08:12:45Z
• Authors: Sofia Carnevali; Philippe Fillion
• Keywords: Entrainment (biomusicology); Stratification (seeds); Code (set theory); Risk Stratification

International audience<br/>This paper presents the assessment of CATHARE 3 code against tests performed in the horizontal TPTF (TwoPhase Tests Facility) and Mantilla facilities. This activity falls within the framework of a benchmark conductedby the Forum & Network of System Thermal-Hydraulics Codes in Nuclear Reactor Thermal-Hydraulics (FONESYS).The aim of this benchmark is to highlight the capabilities of system thermal–hydraulic codes to predict thehorizontal stratification criteria and the onset of droplet entrainment and entrainment rate. One of the objectivesof horizontal TPTF (TPTF-H) experiments, conducted by JAERI (Japan), was to analyse the thermal–hydraulicresponses in the horizontal legs of Light Water Reactors. The considered tests were at steady state and saturatedsteam/water two-phase flow conditions for a pressure varying between 3 MPa and 12 MPa. CATHARE codesimulations show a general rather good agreement with TPTF-H experimental results although some improvementslike the stratification regime prediction seem necessary. In two horizontal test sections with differentdiameters, Mantilla carried out air/water experiments at low pressure, from stratified to annular flow conditions,including droplet entrainment. Entrainment fraction obtained both with the two-fluid 6-equation model and the3-field model of CATHARE are compared against the experimental data. Some improvements of the existingmodels are proposed for the entrainment and deposition processes to better fit the experiments.<br/>