IMPROVEMENT OF DIRECT-CONTACT CONDENSATION MODEL OF RELAP5 MOD3.1 FORPASSIVE HIGH-PRESSURE INJECTION SYSTEM/

A simple set of the transition criterion of the condensation regimes a nd the heat transfer coefficients on the direct contact condensation i n the core makeup tank was developed, and implemented in RELAP5/MOD3.1 . The condensation regimes were divided into two ones: supply limit an d condensation limit. In modeling the transition criterion between two regimes, a large-eddy model developed by Theofanous was used. The mod ified code better predicted the experiments on the core makeup tank us ing small scale test facility than the original code did. (C) 1997 Els evier Science Ltd.