Development and preliminary validation of a steam generator 3D thermohydraulics analysis code STAF

Highlights: • A steam generator thermohydraulics analysis code STAF is developed based on FLUENT. • Heat transfer from primary to secondary side is calculated during iteration in STAF. • Localized flow characteristics in steam generator can be obtained by STAF. • STAF is validated by simulating the AP 1000 steam generator. • STAF is validated by FRIGG test. - Abstract: Porous media model in Fluent code, coupled with two-phase mixture flow model, resistance model of tubes and heat transfer model through tubes, is employed to develop a steam generator thermohydraulics analysis code STAF (Steam generator Thermohydraulics Analysis code based on Fluent). In this code, the heat transfer from primary to secondary side is calculated three-dimensionally during iteration. The localized velocity, temperature, enthalpy, quality and void fraction in steam generator can be obtained by this code. STAF is validated in two ways. First, STAF is used to calculate the thermal-hydraulic parameters in steam generator of AP 1000. The calculated results are compared with designed values to prove that the coupled heat transfer calculation in STAF is accurate. Second, STAF is employed to simulate the FRIGG test to validate the localized parameter calculation performance by comparing the calculated localized void fraction with test values.