An Integral Effect Test on the LBLOCA Reflood Phenomena for the APR1400 Using ATLASunder a Best-Estimate Condition

Abstract

The Korea Atomic Energy Research Institute (KAERI) had started the operation of the Advanced Thermal-Hydraulic Test Loop for Accident Simulation (ATLAS), which is a thermal-hydraulic integral effect test facility for evolutionary pressurized water reactors of APR1400 and OPR1000. Recently, integral tests for the reflood phase of a large-break loss of coolant accident (LBLOCA) have been performed with the ATLAS after an extensive series of commissioning tests. The reflood tests include both Phase-1 and Phase-2 tests. Phase-1 tests are parametric effect tests for the downcomer boiling phenomena in a reactor pressure vessel during the LBLOCA late reflood period, and Phase-2 tests are integral effect tests for the thermal-hydraulic phenomena in the core and downcomer during the LBLOCA reflood period to provide important thermal-hydraulic parameters such as the peak cladding temperature for the evaluation of the safety analysis code and the corresponding licensing methodology. In the present paper, the LB-CL-14 test, which is an integral effect test on the LBLOCA reflood phenomena for APR1400 using the ATLAS under a best-estimate condition, is analyzed and the major findings are presented. As a typical radial power profile is given to the core heater and the system pressure varies to simulate the APR1400 as realistically as possible, the present test gives the most realistic results among the Phase-2 tests in terms of the peak cladding temperature (PCT) and rewetting time.