Transient Analysis of the Wolsong Units 2/3/4 Moderator for 35% RIH Break with Loss of ECC Injection Using CFX-4.4

Abstract

A 3-D CFD model was developed for the transient simulation of the moderator circulation inside the Calandria vessel, using a commercial code CFX-4.4. For the initial condition, a steadystate moderator circulation was analyzed for 103% full power (Yoon et al., 2002). The transient moderator analysis was performed for the 35% RIH(Reactor Inlet Header) break with loss of ECC(Emergency Core Cooling) injection. Until 40 sec after LOCA, local subcooling in the core region was bounded well over the minimum subcooling of 30 degrees C. For local subcooling below 30 degrees C, film boiling can occur in certain conditions.