Considerations for Modeling Critical Heat Flux Behavior

Abstract

During normal and accidental operations of a light water nuclear reactor, a wide range of thermal-hydraulic conditions may be encountered for which the critical heat flux (CHF) cannot be predicted by a single correlation. An encompassing model was developed for predicting the steady-state forced convective CHF for water over a wide range of thermal-hydraulic conditions. A CHF model is postulated using a conceptual CHF map to define possible CHF mechanisms for given thermal-hydraulic conditions. Existing steadystate CHF correlations, for which the primary CHF mechanism modeled can be identified, are then used in conjunction with the conceptual CHF map to construct a predictive CHF model. The CHF correlations used as the foundation of this model are the Westinghouse-3, the Biasi, and the Modified-Barnett correlations. These correlations allow coverage of a wide range of thermal-hydraulic conditions, provide favorable comparison with experimental data, and are commonly used in the nuclear industry. The parametric ranges covered by the resultant model are 0.3