Semi-implicit modeling of condensation in the presence of non-condensables in the relap5/mod3 computer code Original Research Article

A methodology is developed for modeling condensation in the presence of non-condensables based on the stagnant film (couette flow) model. The methodology, which is fully compatible with the mathematical representation and numerical solution scheme for the two-fluid conservation equations in the relap5/mod3 computer code, rigorously treats the coupling between the heat and mass transfer processes and allows for implicit treatment of the interphase mass and momentum exchange terms without iterations and without adversely affecting the stability of the codeʹs solution scheme. The relap5/mod3 computer code is accordingly modified and is successfully validated against published experimental data.