Thermohydraulic design analysis of PWR U-tube steam generator

Abstract

A computer code, USDA(U - tube Steam Generator Design Analysis Code) for U - tube steam generator design analysis was developed on the basis of the PWR core transient analysis code, THERMIT. The fluid model, which is based on three - dimensional, nonlinear, and two fluid conservation equations for mass, energy and momentum, can account for both compressibility and thermal expansion of fluid flow. The numerical scheme is characterized by the ICE (Implicit Continuous - fluid Eulerian) method and semi - implicit method. In the present work, the original ($x, y, z$) coordinates used in THERMIT were transformed to the cylindrical coordinates ($r,\theta, z$) which are better fitted in the geometry of steam generators. The recirculation flow model was developed to implement the downcomer. The model was developed to account for the U - bend frictional pressure drop by coordinates transformation, which uses the natural geometry coordinates of the U - bend region. Sample calculation was done by using simulation experiments performed by EPRI to check the code.