Abstract: A variety of hazards coexist in nuclear fuel fabrication facilities, so risk assessment is necessary. There are a variety of risk assessment methodologies for risk assessment of nuclear fuel fabrication facilities. HAZOP and LOPA method were selected for UF₆ vaporization process which is the most important in risk assessment of nuclear fuel fabrication facilities. The process deviations which have serious consequences were obtained by HAZOP. The risk reduced by independent protection layers and the residual risk of UF₆ vaporization process were obtained by LOPA.