VALIDATION OF COMMIX WITH WESTINGHOUSE AP-600 PCCS TEST DATA

Small-scale test data for the Westinghouse AP-600 Passive Containment Cooling System (PCCS) have been used to validate the COMMIX computer c ode. So that the performance of the PCCS can be evaluated, two transie nt liquid-film tracking models have been developed and implemented in the COMMIX code. A set of heat-transfer models and a mass transfer mod el based on heat and mass transfer analogy were used for the analysis of the AP-600 PCCS. The flow of the air stream in the annulus is a hig hly turbulent forced convection and the flow of the air-steam mixture in the containment vessel is a mixed convection. Accordingly, a turbul ent-forced-convection heat-transfer model is used on the outside of th e steel containment vessel wall and a mixed-convection heat-transfer m odel is used on the inside of the steel containment vessel wall. The r esults from the COMMIX calculations are compared with the experimental data from Westinghouse PCCS small-scale tests for average wall heat f lux, evaporation rate, containment vessel pressure, and vessel wall te mperature and heat flux distributions; agreement is good. The COMMIX c alculations also provide derailed distributions of velocity, temperatu re, and steam and air concentrations.