Abstract:In order to solve the problem that the reference radiation field should be provided for field calibration of fixed radiation dose rate monitoring instruments used for on-site online monitoring, this work developed a portable radiation source irradiation device based on γ source using Monte Carlo simulation method. The radiation source shielding switch gears are not less than 3, the surface leakage ray is lower than 0.5% compared with the useful ray beam, and the radiation field non-uniformity is less than 5%, which meet the fixed X or γ radiation dose meter field calibration needs. The study has improved the quantity transfer ability for the field calibration of the fixed dose rate meters.