[en] A thermal-hydraulic integral effect test facility for advanced pressurized reactors (PWRs), ATLAS (Advanced Thermal-hydraulic Test Loop for Accident Simulation), has been operated by KAERI (Korea Atomic Energy Research Institute). The reference plant of the ATLAS is a 1400 MWe-class evolutionary pressurized water reactor (PWR), APR1400 (Advanced Power Reactor 1,400 MWe), which was developed by the Korean industry. The ATLAS has a 1/2 reduced height and 1/288 volume scaled integral test facility with respect to the APR1400. It has a maximum power capacity of 10% of the scaled nominal core power, and it can simulate full pressure and temperature conditions of the APR1400. The ATLAS could be used to provide experimental data on design-basis accidents including the reflood phase of a large break loss of coolant accident (LBLOCA), small break LOCA (SBLOCA) scenarios including DVI line and cold leg breaks, a steam generator tube rupture, a main steam line break, a feed line break, etc. A 6 inch cold leg break test (SB-CL-02) was carried out as one of the SBLOCA spectrum. Main objectives of this experimental test are not only to provide physical insight into the system response of the APR1400 reactor during the transient situation but also to present integral effect data for validation of the SPACE (thermal hydraulics Safety and Performance Analysis Computer Code) which is now under development by the Korean nuclear industry.