An Integral Effect Test for a Best-Estimate Condition during the Reflood Phase of a LBLOCA using the ATLAS (LB-CL-11)

A thermal-hydraulic integral effect test facility, ATLAS, has been constructed at KAERI. It is a 1/2 reduced height and 1/288 volume scaled test facility based on the design features of the APR1400. The present LB-CL-11 test is one of the integral tests for investigating the thermal-hydraulic characteristics during an entire reflood period, and for providing reliable data to help validate the LBLOCA analysis methodology for the APR1400. The initial and boundary conditions were obtained by applying scaling ratios to the MARS simulation results for the LBLOCA scenario of the APR1400. The core heater power was given to simulate the decay heat of 1.02 times that of the ANS-79 curve for a best-estimate condition and its initial value was 830.9 kW. The simulated ECC water flow rate from the SIP was 0.32 kg/s. The system pressure was fixed at around 0.20 MPa to simulate a best-estimate condition and the initial outer wall temperature of the RPV down-comer was 209 .deg. C. The experimental results showed the typical thermal-hydraulic trends expected to occur during the reflood phase for a LBLOCA scenario for the APR1400. The core heater rod was reheated up to a maximum surface temperature of 558 .deg. C and the maximum rewetting velocity was about 0.87 cm/s with 218 seconds duration