Experimental program for validation of cooling and operational performance of the APR+ Passive auxiliary feedwater system

PAFS (Passive Auxiliary Feedwater System) is one of the advanced passive safety systems adopted in the APR+ (Advanced Power Reactor plus), which is intended to completely replace the conventional active auxiliary feedwater system. PAFS cools down the steam generator's secondary side, and eventually removes the decay heat from the reactor core by introducing a natural driving force mechanism; i.e., condensing steam in nearly horizontal U-tubes submerged inside the passive condensation cooling tank (PCCT). With an aim of validating the cooling and operational performance of the PAFS, an experimental program is in progress at KAERI (Korea Atomic Energy Research Institute), which is composed of two kinds of tests; the separate effect test and the integral effect test. The separate effect test, PASCAL (PAFS Condensing Heat Removal Assessment Loop), is in progress to experimentally investigate the condensation heat transfer and natural convection phenomena in PAFS. The integral effect test is being performed to confirm the operational performance of the PAFS coupled with the other reactor coolant systems (RCS) using the thermal hydraulic integral effect test facility, ATLAS (Advanced Thermal hydraulic test Loop for Accident Simulation). This paper summarizes the up to date experimental results of the separate effect test and the integral effect test for PAFS from a cooling and operational performance point of view