FLOODING-LIMITED THERMAL MIXING - THE CASE OF HIGH FROUDE-NUMBER INJECTION

Stratification in the cold leg due to high-pressure injection in a stagnated loop of a pressurized water reactor is considered. The working hypothesis is that at high injection Froude numbers, the extent of mixing approaches a limit controlled only by the flooding condition at the cold-leg exit. Experimental data available support this hypothesis. Predictions for reactor conditions indicate a stratification of approximately 40-degrees-C. As a consequence, the downcomer plume would be rather weak (with a low Froude number) and would be expected to decay quickly.