Numerical Study on the Local Temperature in IRWST Pool Available to Purchase

The Safety Depressurization Vent System (SDVS) of APR 1400 prevents Reactor Coolant System (RCS) from over-pressurization by discharging high pressure and temperature coolant through the I-sparger into the IRWST during an accident. If IRWST water temperature rises locally, around the sparger, beyond 200 °F by the discharged coolant, unstable steam condensation may occur and cause large pressure load on the IRWST wall. To investigate whether this condition could be avoided along with the most severe accident, Total Loss of Feed Water (TLOFW) event and to find the local temperature location for the I-typed sparger in APR 1400, the flow and temperature distribution of water in the IRWST pool is calculated by using CFX 4.4 computational fluid dynamic code. According to the results, the IRWST water temperature does not exceeds temperature limit upto 15 seconds after the opening of POSRVs. The location of the local temperature is estimated as the location above and below of the sparger discharge head by examining the flow and temperature field.