Nonhomogeneous-Nonequilibrium Two-Phase-Flow model for nuclear reactor Single-Channel stability analysis

The effects of two-phase-flow modeling on nuclear reactor single-channel stability analysis are investigated with four two-phase-flow models, namely, the homogeneousequilibrium model, the homogeneous-nonequilibrium model, the nonhomogeneous-equilibrium model, and the nonhomogeneous-nonequilibrium model. The models are applied to hot-channel analyses of a proposed typical supercritical-water-cooled-reactor (SCWR) design. The neutral stability boundaries derived by using the four mod- els are compared and plotted on the traditional subcooling number versus phase change number plane. To ensure proper development of the models, they are benchmarked to the experimental data. It is found that the homogeneous models predict more conservative stability boundaries than the nonhomogeneous models and that the differences of the stability boundaries predicted by all four two-phase-flow models are reduced under higherpressure conditions.