拉萨市天然石材放射性水平调查

目的 对拉萨市天然石材进行放射性水平调查研究，了解其放射性核素比活度范围及使用限制。方法 对拉萨市各天然石材矿区进行辐射监测和调查取样，对采集的样品进行放射性核素含量分析，根据分析结果计算内、外照射指数，并根据建筑材料放射性核素限量标准进行分类。结果 拉萨市天然石材样品中⁴⁰K、²²⁶Ra、²³²Th和²³⁸U比活度均值分别为912、59.0、77.1和64.4 Bq/kg，样品内、外照射指数均<1。结论 本次调查的拉萨市产天然石材放射性核素含量水平总体低于全国平均水平，可作为建筑主体材料及A类装饰装修材料。

Investigation on the radioactivity level of natural rock in Lhasa

Objective To investigate the radioactivity level of natural rocks in Lhasa in order to obtain the radionuclide contents and availiability of the rock. Methods Radiation monitoring and sampling were carried out in the natural rock mining area in Lhasa, and the contents of radionuclides in the samples were analyzed. Both internal and external exposure indexes were calculated, and the rocks were classified according to the relevant national standards on building materials. Results The average specific activity of ⁴⁰K, ²²⁶Ra, ²³²Th and ²³⁸U in the rock samples were 912, 59.0, 77.1, and 64.4 Bq/kg, respectively. Internal and external exposure indexes were both less than 1. Conclusions The radioactivity level in natural rocks in Lhasa were lower than the national levels. The natural rocks could be used as main building materials and Class A decoration materials.