Abstract: In order to address the radiation protection during equipment maintenance and overhaul of HTR-PM high-temperature gas-cooled reactor (HTGR) spent fuel storage system, a three-dimensional model of the spent fuel storage tank and its related compartments was established. The gamma dose rate at staff maintenance location was calculated using the Monte Carlo method. The results show that: the dose rate decreases rapidly with the increase of the distance between the assessed point position and the opening of the concrete platform; due to the existence of holes on the shielding cover and the concrete floor slab, a high dose rate directly above the holes on the concrete platform of the spent fuel loading room was found. Considering the 2-fold safety coefficient, the dose rate is in the range of the red zone around 50 cm from the center of the holes, and the entry of personnel into the area should be strictly limited; the point of radiation protection in the service equipment room is in the range of 30-70 cm from the center of the holes. The dose rate within 30-70 cm from the center of the maintenance equipment room is in the restricted working area (orange zone), and the working time of the personnel in this area should be as short as possible. In order to ensure safety, it is recommended to carry out physical simulation training and shorten the working time, to set up a temporary shield of lead sand not less than 16 cm and protective equipment, and to decontaminate the local hot spots to reduce the intensity of the source term.

Key words: HTGR, spent fuel storage system, radiation protection, Monte Carlo methosd