Abstract: ¹³⁷Cs is an artificial radionuclide that has been paid special attention in environmental monitoring of nuclear facilities. In this paper, the ¹³⁷Cs radioactivity level in soils around a nuclear facility was statistically analyzed, and was compared with similar nuclear facilities from 2012 to 2021. The background deduction method was established for the external radiation dose caused by ¹³⁷Cs in soils, and the resident external radiation dose caused by ¹³⁷Cs in soils around the nuclear facility was estimated. The results showed that the activity concentration of ¹³⁷Cs in soil samples around the nuclear facility decreased first and then increased from 2012 to 2021, and the average activity concentration of 1.81 Bq/kg in recent ten years was slightly higher than that of similar nuclear facilities. From the point of view of monitoring locations, four of the six locations with the highest average ¹³⁷Cs activity concentration are distributed within a 2 km radius of the nuclear facility. The annual effective dose caused by ¹³⁷Cs from soil samples around the nuclear facility was 1.24 μSv, which was only 0.5% of the target annual dose for the public specified for the nuclear facility.

Key words: soil, cesium-137, external exposure, evaluation