THE TOP-DOWN REFLOODING MODEL IN THE CATHARE CODE

A top-down reflooding model was developed for the French best-estimate thermal hydraulic code CATHARE. The paper presents the current state of development of this model. Based on a literature survey and on comp atibility considerations with respect to the existing CATHARE bottom r eflooding package, a falling film top-down reflooding model was develo ped and implemented into CATHARE version 1.3U. Following a brief revie w of previous work, the paper describes the most important features of the model. The model was validated with the Winfrith single-tube top- down reflooding experiment and with the REWET-II simultaneous bottom a nd top-down reflooding experiment in a rod bundle geometry. The result s demonstrate the ability of the new package to describe the falling f ilm rewetting phenomena and the main parametric trends both in a simpl e analytical experimental set-up and in a much more complex rod bundle reflooding experiment.