Analysis of Radon Radiation Level in the Air of Wuhan Subway Stations during Completion Acceptance

Objective To measure and evaluate the radon concentration of each line of Wuhan Metro during completion acceptance, to understand the radon radiation level in the metro before operation.

Methods Continuous radon monitoring was performed with the electronic radon detector RAD7 to measure radon and its daughters in the air of 63 stations of 7 metro lines in Wuhan. The vehicle control room, station hall floor and platform floor were measured by the uniform placement of plum pattern points. The measurement results were evaluated in accordance with the Requirements for radiological protection for radon in public underground structure and using geothermal water (WS/T 668-2019).

Results The median of radon concentration of the 63 stations of the 7 metro lines in Wuhan was 12.20 Bq/m³. The median radon concentration for Zhifang Line was 36.80 Bq/m³, which was the highest, and that for Line 2 was 4.00 Bq/m³, which was the lowest. There was a significant difference in radon concentration among different lines (χ²=252.24, P < 0.01). The median radon concentration in vehicle control rooms (22.11 Bq/m³) was the highest, and that in concourses (4.92 Bq/m³) was the lowest. There was a significant difference in radon concentration among different areas (χ²=30.46, P < 0.01).

Conclusion The radon radiation level in the air of Wuhan Metro does not exceed the national standard limit, but ventilation in vehicle control rooms needs to be enhanced.