Prediction of Pressurizer Transient by the IDRIFF Two-phase Simulation Code

Abstract

A small scale pressurizer made of a glass tank and its associated systems were set up to simulate the behaviour of a nuclear power plant pressurizer. A version of the IDRIFF two-phase simulation code is specially designed to simulate the experiments such that any particular pressurizer phenomena of interest can be calculated in detail without the necessity of performing unnecessary detailed calculations on the other aspects. The code consists of two major model components: (1) lumped formulation for the fluid conservation equations and the equation of state; (2) sets of one-dimensional drift-flux equation and the equation of state written in differential forms. The study on three types of pressurizer transients is reported in the present paper. They are: (a) transients following a step-wise change in heater power; (b) transients following step-wise change in steam bleed valve opening; and (c) transients following sudden and short-lived outsurge and insurge. The results of the simulation are in good agreement with experimental measurements. By analyzing the effect of a single parameter while isolating the effect of others, several useful insights on the behaviour of the pressurizer were obtained.