华东某铀矿区周边河流表层沉积物的天然放射性评价

利用高纯锗γ能谱分析仪测量中国华东某铀矿区附近河流沉积物的放射性核素比活度,计算γ辐射吸收剂量率(D)、有效镭浓度(Ra_(eq))、外照射指数(H_(ex))、内照射指数(H_(in))、年有效剂量当量(AEDE(室内和室外))和年性腺剂量当量(AGDE)等放射性参数,并开展沉积物的放射性危害评估,最后通过Pearson线性系数确定放射性核素比活度之间的相关性。结果表明,河流沉积物中放射性核素~(238)U、~(226)Ra、~(232)Th和40K的平均比活度分别为51.55、37.32、57.63和756.86 Bq·kg~(-1),除~(226)Ra外,其他放射性核素的比活度均高于中国平均值;距离污染区较远或存在河流稀释作用的区域,沉积物的天然放射性核素处于正常水平,作为建筑材料使用时比活度不存在超标;放射性核素~(238)U、~(226)Ra和~(232)Th之间存在显著相关性。

Natural Radioactivity Evaluation of Surface Sediments of Rivers around a Uranium Mining Area in East China

The specific activity of ²³⁸U, ²²⁶Ra, ²³²Th, and ⁴⁰K in the river sediments near a uranium mine in East CH_ina was measured using high purity gamma spectrometry analyzer. The gamma radiation absorbed dose rate (D), radium equivalent activity (Ra_eq), external hazard indices (H_ex), internal hazard indices (H_in), annual effective dose equivalent (AEDE (indoor and outdoor)), and annual gonadal dose equivalent (AGDE) were calculated, and an assessment for radioactive hazards of the sediments was then conducted. The correlation of the radionuclide concentrations was determined by calculating and analyzing the Pearson linear coefficient. The results indicated that the average specific activities of ²³⁸U, ²²⁶Ra, ²³²Th, and ⁴⁰K in the river sediments were respectively 51.55, 37.32, 57.63, and 756.86 Bq kg^?1. Except ²²⁶Ra, all the average specific activities of radionuclides are higher than the limited values of the averages in CH_ina. For the areas far from the pollution sources or with dilution of river water, the activities of natural radionuclide in the sediments remains at a normal level, which can be therefore used as a building material. A significant correlation between the radionuclides ²³⁸U, ²²⁶Ra and ²³²Th was observed.