An experimental study on evaporative heat transfer coefficient and applications for passive cooling of AP600 steel containment

After TMI and Chernobyl accidents, many efforts have been made to enhance t he nuclear safety with passive features. Among such passive features, the p assive containment cooling system (PCCS) has been suggested by Westinghouse in the AP600 plant. The containment with PCCS is a dual containment, and c onsists of a stainless steel vessel and a concrete wall. In the gap between these structures, air and water can counter-currently pass and cool the st eel surface. This paper experimentally investigates evaporative heat and ma ss transfer at the surface of a falling water film with counter-current air flow in a vertical duct with one-side heated plate. Experiments included v arious conditions of mass flow rate of film and air. Experimental results s how the strong effects of water temperature and air mass flow rate, but lit tle effect of the water flow rate. Also, simple analyses based on heat and mass transfer analogy were performed to evaluate the experimental results. With experimental data, a new correlation on evaporative mass transfer coef ficient was developed, and with the correlation, the containment pressure a nd temperature was calculated for the design basis accident of AP600 by the use of CONTEMPT4/MOD5 code implementation. (C) 2001 Elsevier Science B.V. All rights reserved.