Recent achievement and future prospects of the ATLAS program

•Major achievements of the ATLAS test program are highlighted in conjunction with domestic and international cooperative programs.•Recent ATLAS data were focusing on beyond DBA and design extension conditions.•A plan is introduced covering beyond DBAs associated with multiple failures. As a critical thermal-hydraulic test facility, the ATLAS facility has been widely utilized since its first commission test in 2006 to resolve urgent safety concerns raised by nuclear industries and regulatory body, to verify the performance of new safety systems, to validate safety analysis codes, and to provide a cooperation network for developing safety analysis capabilities. In the first phase of the ATLAS program, major R&D efforts were put into producing code validation data to support the standard design approval of the APR1400 when design basis accident (DBA) scenarios were the main interest of the program. In the following phase, the ATLAS program’s focus shifted to beyond DBA scenarios, and the OECD-ATLAS international joint project started reflecting the safety concerns of many NEA countries following the Fukushima Daiichi disaster in 2011. In this paper, the current status of the ATLAS program, including the OECD-ATLAS Phase-1 and 2 projects, are briefly described together with their major outcomes. The next R&D program based on the ATLAS platform is also briefly discussed.