In order to evaluate the safety of helium cooled blanket system of China Fusion Engineering Test Reactor (CFETR) and optimize the blanket design, this study presents the initial events of accidents, and determines the accident list and design basis accidents based on the design characteristics of CFETR helium cooled blanket. The thermal hydraulic steady-state analysis of CFETR helium cooled blanket module is carried out by using the best transient estimation program RELAP5. The preliminary safety analysis of accident transient is carried out according to the requirements of design basis accident. The results show that the LOCA accidents in different positions should be focused on in the accident safety analysis of helium cooled blanket system; The in-vessel LOCA large break accident is analyzed and calculated, and the maximum temperature of the first wall and the maximum pressure in the vacuum vessel are given, which meet the requirements of the acceptance criteria. Copyright ©2021 Nuclear Power Engineering. All rights reserved.
