Simple model for calculating steam entrainment into the downcomer of a nuclear heating reactor

On the basis of flow performance in a nuclear heating reactor of integrated type using natural circulation of the coolant flowing as a two-phase mixture in several sections, the gas fraction, ψ, entrained into the downcomer is defined which is of importance for stable operation of the reactor. Analysis of the experimental investigations hitherto carried out has resulted in identifying a variety of influencing factors which are classified and, for the most part, enter into the model developed for calculating the entrainment coefficient ψ. Comparison with experimental data shows that the calculational model satisfactorily reflects the physical dependencies in first approximation. (author)