ASSERT 4 Simulation of the Distribution of Aow, Temperature and Critical Heat Flux in Horizontal Channels at High Pressure

Abstract

The ASSERT subchannel code has been developed specifically to model flow and phase distributions within CANDU fuel channels. ASSERT uses a drift-flux model, which permits the phases to have unequal velocities and temperatures and thus can model phase separation tendencies which may occur in horizontal flow. This paper briefly summarizes the non-equilibrium models used in the ASSERT code, the equations used to represent these models, and the algorithms used to solve the equations numerically. The paper then gives some results from recent validation exercises in which the code results were compared to three sets of experiments completed in horizontal channels at pressures typical of CANDU conditions.