Transient condensation heat transfer coefficient expressions during and after blowdown

Analytical expressions are presented for calculating condensation heat transfer coefficients during and after blowdown at specific locations in a containment structure. A forced convention model is used during and immediately after blowdown when much turbulence exists, and a free convection model is used after blowdown end when the turbulence subsides. The forced convection expression depends primarily on a turbulent velocity relationship which is dependent on the distance from the break. The free convection expression depends on the wall-mixture temperature difference and the ratio of air partial pressure to total air-steam pressure. Experimental results were used to refine both of these expressions. Recommendations are given on how they are to be used. Calculations are compared with experimental values. (orig.)