The decommissioning of Kori unit 1 is just around the corner. Accordingly, it is required to construct a hot cell facility for decommissioning nuclear power plants to analyze the characteristics of intermediate-level waste and low-level waste generated in the decommissioning process. In this study, a Design Base Accident (DBA) scenario of the facility is developed. To identify and characterize potential hazards at the facility, a Preliminary Fact Sheet (PFS) is filled out and consider external events in consideration of the surrounding site environment. The external event screening and evaluation method is based on the external event evaluation method covered in the probabilistic risk assessment. In PFS, only natural and artificial hazards that may have a meaningful impact on the facility are considered as the sources of the accident, and accident prevention and mitigation systems, etc., which exist in each compartment or facility, are described. Based on PFS and external events, potential hazard assessment is systematically performed using each potential hazards, impact and defense function identified using the preliminary hazard analysis (PHA) methodology. The potential hazard analysis methodology applied to this assessment is a qualitative assessment method consistent with the US DOE Hazard Analysis methodology (DOE 1992b; DOE 1994b). After that, the potential mitigation functions that can be used under normal, abnormal and accident conditions are examined, and the contribution of public and workers to safety is evaluated. The results of the PHA are basic data that prioritize potential hazards and can be used to develop potential accident scenarios. Among potential hazards generally considered for non-reactor facilities, only possible accidents during operation of the facilities are selected as potential hazards. The level of potential hazards is obtained by qualitatively examining the frequency and consequence estimates for each hazard or accident scenario developed in PHA. Based on the results of the potential hazards assessment, representative accidents that require further quantitative analysis are screened. Selected accidents are DBA and are the most dangerous and most significant impacts on workers.