Introduction of the ATLAS Test Facility Upgrade

The ATLAS(Advanced Thermal-hydraulic Test Loop for Accident Simulation) is one of the three largest integral effect test facilities in the world. The reference plant of the ATLAS is the APR1400 (Advanced Power Reactor 1400 MWe), which has a rated thermal power of 4000 MW and a loop arrangement of 2 hot legs and 4 cold legs for the reactor coolant system. The ATLAS was designed to investigate major design basis accidents and operational transients that may occur in a reactor coolant system. Since the first operation of the ATLAS in 2007, the operational technique and managing system of the ATLAS facility have been satisfactorily established. During previous operating experiences. During last 10 years, the instrumentation and measurement techniques were developed significantly. Through these changes of the ATLAS, it is possible to produce more accurate and delicate experimental results and the result analysis can be more confident. Making the best use of new ATLAS, scope of the code validation will be enhanced with the contribution of the safety improvement of the accident management procedure of the nuclear power plant.