Abstract: Under the accident conditions in which the spent fuel pool loses cooling capacity and water supply completely, the dose rate in the spent fuel operating hall of the pressurized water reactor nuclear power plant will gradually increase as the water level of the spent fuel pool decreases. In this paper, the spent fuel pool of a typical pressurized water reactor nuclear power plant is taken as the research object, and the QAD-CGGP program is used to calculate and analyze the distribution of the dose field in the spent fuel operating hall and its variation with the water level. The calculation results show that: (1) In the range of 3.786-7.736 m water layer thickness, the change of dose rate above operating platform with water layer thickness is not obvious. (2) The peak dose rate above spent fuel pool locates above the high-density grid area. (3)In the range of 3.436-4.736 m water layer thickness, the peak dose rate above spent fuel pool changes in the range of 0.914-288 μSv/h and increases exponentially with the decrease of the thickness of the shielded water layer, and dose rate above operating platform meet the radiation zoning requirements of the spent fuel operating hall. (4) The lowest shielding water level needed to meet the radiation zoning requirements of the spent fuel operating hall is +15.77 m.

Key words: spent fuel pool, dose rate, QAD-CGGP, spent fuel assembly source, lowest shielding water level