广东下庄铀矿田土壤的天然放射性研究

Studies on natural radioactivity of soil in Xiazhuang uranium ore field, Guangdong

用γ能谱分析方法测量了广东下庄铀矿田土壤中放射性核素226Ra,232Th和40K的含量,分别为111.7(40.2～441.5)Bq/kg,71.5(32.6～ 88.1)Bq/kg, 672.1(441.8～912.6)Bq/kg.同全国和广东省的平均值相比,226Ra的含量明显偏高.在此基础上,计算了距地面1m高处空气(辐射吸收剂量率、等效镭浓度和外照射指数,平均值分别为123.9nGy/h, 265.7Bq/kg, 0.7,表明广东下庄铀矿田的(辐射外照射水平远高于正常值.应用氡的对流和扩散理论,计算了空气中氡的理论浓度,平均值为80.2Bq/m3,计算结果与实测值基本吻合.

The contents of radioactive nuclides 226Ra, 232Th and 40K in the soil of Xiazhuang uranium ore field Guangdong were measured using γ-ray spectra analysis, these contents were 111.7(40.2 - 441.5), 71.5(32.6 - 88.1), 672.1(441.8 - 912.6) Bq/kg, respectively. Compared with the average value of Guangdong Province and countrywide, the content of 226Ra was higher obviously. On this basis, the absorbed dose rate, the radium concentration of equivalent effect and the external irradiation index in the air 1m above ground surface were calculated, these contents were 123.9 nGy/h, 265.7 Bq/kg and 0.7 in average, respectively. The γ-radiation external irradiation level of Xiazhuang uranium ore field Guangdong was much larger than normal value. The theoretical concentration of radon in air was calculated applying the convection and dispersion theories, the content was 80.2 Bq/m3 in average, which was approximately in accord with the measured value in field.