Abstract: During the maintenance or decommisioning of nuclear facilities, it is often necessary to measure the radiation dose rate field on site. Traditional dose rate meters do not support spatial coordinate measurement and require additional coordinate measurement tools. Additionally, dose rate measurement and coordinate measurement are not synchronized, which limits measurement efficiency. A measurement method based on total station positioning was proposed, which can simultaneously measure dose rates and corresponding spatial coordinates with a positioning accuracy of mm level. A prototype measurement system was developed. The prototype was used to conduct testing experiments on a cement solidified radioactive waste container, and the outcomes were compared against Monte Carlo calculations. The discrepancy between the measured and simulated values conforms to a normal distribution, with an average deviation of 12.8% and a standard deviation of 9.37%. The relative deviation of approximately 96% of the measurement points is within the range of [-30%, 5%], reflecting high measurement accuracy. Radiation field assessments were also conducted in two other intricate settings within a nuclear facility structure. The interpolation of radiation fields at discrete measurement points was performed using the logarithmic transformation ordinary Kriging method. When measurement points were appropriately chosen, the average relative deviation in the three-dimensional radiation field reconstruction results could be maintained at approximately 50%. The results indicate that the radiation field measurement system based on total station can reconstruct the 3D radiation field on site, and the accuracy can meet the application requirements.

Key words: γ radiation field measurement, reconstruction of three-dimensional radiation field, total station positioning, ALARA