[en] To improve the prediction capability of safety analysis code for the phenomena occurring in the advanced safety system of new nuclear plant, the local physical model should be developed based on the fine scale of experimental data for the key phenomena. The current study performed high-precision experiment and constructed database for key phenomena for the boiling induced natural convection inside cooling tank and tube inside condensation of heat exchanger of passive auxiliary feedwater injection system, dynamic multi-dimensional behaviour of ECC water inside downcomer from DVI system. To achieve local high-precision experimental data, measuring technique was newly developed or improve the applicability of the conventional instrument such as optical probe, laser optics including PIV, LDV and LIF, and ultrasonic measuring techniques. Based on the force or energy balance, mechanistic physical models were uniquely developed for the bubble departure diameter on curved heated surface, condensation heat transfer inside heat exchanger tube and interfacial shear on the liquid film. The boiling phenomena is very important for the heat transfer and thermal margin evaluation of reactor safety. experiment for high heat flux condition was performed using high resolution of visualization. From the visualization, the boiling structure and mechanism near CHF condition was analyzed. As one of the key boiling parameter, a bubble departure size model was newly developed based on balance equation of heat transfer. The experimental database and unique mechanistic physical models developed in this study, will enhance the brand value and the accuracy of the prediction capability of the domestic safety analysis code, which will contribute to the nuclear plant export.

[en] A thermal-hydraulic integral effect test facility, VISTA-ITL, for the SMART design has been constructed by the Korea Atomic Energy Research Institute (KAERI). Three SBLOCA tests were successfully performed using the VISTA-ITL facility. The breaks are guillotine breaks and their locations are on the SIS line (nozzle part of the RCP discharge), on the suction line of the SCS (nozzle part of the RCP suction), and the pressurizer safety valve (safety valve line connected to the pressurizer top). In this study, the SIS line-break SBLOCA test of SB-SIS-07 using VISTA-ITL has been discussed in detail. Also, a post-test simulation on the SBLOCA test (SB-SIS-07) has been performed with the MARS-KS code to assess its simulation capability for the SBLOCA scenario of the SMART design. The SBLOCA scenario in the SMART design was well reproduced using the VISTA-ITL facility, and the measured thermal-hydraulic data were properly simulated with the MARS-KS code. The present analysis results on SBLOCA can provide a good understanding on the thermal-hydraulic characteristics of the SBLOCA behavior of the SMART design. (author)