The evaluation of radiation hygiene in thermal spring water utilization in Xianning

Objective: To evaluate the development in radiation hygiene of thermal spring water utilization. Methods: Gamma dose rate in the circumstances of thermal spring was determined with FD-3013 gamma instrument. The concentrations of 222Rn and its daughter in the air in two places of Xianning [XN(A) and PQ(B) ] were determined by using ionization chamber, α-track detector monitor, double-filter method, Markov potential energy method and scintillating chamber respectively. Content of 226Ra and 222Rn in the water was also measured with the above methods to estimate the dose on bathers and staffs. Radon area exhalation in the soil in the vicinity of spring was determined with ionization chamber. The natural radioactive substance content was determined for fishes, in thermal spring water, farm products irrigated with such water and other biological samples. Results: The gamma dose rate in the circumstances of thermal spring was markedly higher than that of other places. The content of 226Ra and 222Rn in Ra-abundant spring water was (1.65 ± 0.03) Bq·L-1 (place A); (1.62 ± 0.02) Bq·L-1 (place B) and (231.20 ± 12.12) Bq·L-1 (place A); (230.40 ± 13.02) Bq·L-1 (place B). The average content of 226Ra in spring water was (1.62 ± 0.02) Bq·L-1 (place A, B), which surpassed the national standard of drinking water. 222Rn and its daughter's potential alpha energy concentration of bath room atmosphere was (308.60 ± 15.20) Bq·m-3 (place A), (210.20 ± 12.60) Bq·m-3 (place B) and (38.50 ± 1.60) mWL(place A), (28.00 ±1.40) mWL(place B). Judged with the transmission index which was reported by UNSCEAR in 1993, the annual effective dose equivalent of staffs in bath rooms was 8.42 mSv, 5.76 mSv respectively. Radon area exhalation in the soil in the vicinity of spring was much higher than that in the control area (P<0.05). The fish, poultry and farm products that bred by thermal spring water were contaminated to different extents by U-Ra. Conclusion: Except for using drinking water, other utilizations of thermal spring water are under the limitations of national health standard. Workers whose job involves the use of thermal spring water should pay attention to 222Rn protection