A thermal-hydraulic integral effect test facility, ATLAS (Advanced Thermal-hydraulic Test Loop for Accident Simulation), is being constructed at the Korea Atomic Energy Research Institute (KAERI). The ATLAS is a 1/2 reduced height and 1/288 volume scaled test facility based on the design features of the APR1400, an evolutionary pressurized water reactor developed by the Korean industry. The simulation capability of the ATLAS for major design basis accidents (DBAs), including a large-break loss-of-coolant (LBLOCA), DVI line break and main steam line break (MSLB) accidents, is evaluated by the best-estimate system code, MARS, with the same control logics, transient scenarios and nodalization scheme. The validity of the applied scaling law and the thermal-hydraulic similarity between the ATLAS and the APR1400 for the major design basis accidents are assessed. It is confirmed that the ATLAS has a capability to maintain an overall similarity with the reference plant APR1400 for the major design basis accidents considered in the present study. However there is an inconsistency in certain thermal hydraulic parameters such as the break flow rate, core water level, etc. It is mainly due to the limitation of the decay power level of 8%. Therefore, a more systematic control is needed in order to overcome the core power limit of 8%. The present similarity analysis was successful in obtaining a greater insight into the unique design features of the ATLAS and would be used for developing the optimized experimental procedures and control logics.
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