[en] This project is to provide the regulatory direction of 4 major technical issues for the Korean Next Generation Reactors, which are parts of major technical issues resulted from the safety regulation R and D on the KNGR. The outstanding results are as follows : reliability of risk significant SSCs established during design stage must be maintained through the operating life of the plant, currently used classification method of plant conditions and safety requirement were reviewed, and a quantitative classification method is needed to be developed further, the basic regulatory directions are proposed for multiple failures such as SBO, TLOFW, multiple SGTR and ATWS, safety requirements are proposed for survivability/availability of severe accident mitigation design features by 5 items if basic requirements, selection of initial event, identification of available equipment and instruments, identification of environmental conditions and verification methods