我国部分地区煤矿原煤中天然放射性水平调查分析

目的 了解我国部分地区煤矿原煤中天然放射性核素⁴⁰K、²²⁶Ra、²³²Th和²³⁸U的活度浓度，探讨不同活度浓度的矿石与工作场所氡及其子体浓度的关联性。方法 采集5省12家煤矿的原煤样品，使用高纯锗γ能谱测量系统测量其中的⁴⁰K、²²⁶Ra、²³²Th和²³⁸U活度浓度。结果 12家煤矿原煤样品中4种天然放射性核素活度浓度均低于1000 Bq/kg，其中有1家煤矿²³⁸U活度浓度接近100 Bq/kg；不同煤矿⁴⁰K、²²⁶Ra、²³²Th和²³⁸U的含量差别很大，但对同一煤矿²²⁶Ra、²³²Th和²³⁸U含量基本在相同水平上。结论 12家煤矿均不属于伴生放射性矿，有1家煤矿接近限制使用管理类矿山标准限值，建议开展原矿、中间产品、尾矿（渣）或者其他残留物中²²⁶Ra的含量与氡及其子体浓度的关联性研究，并对²²⁶Ra、²³²Th和²³⁸U 3种天然放射性核素活度浓度较高的煤矿加强其衰变链中氡及其子体监测与防护。

Natural radioactive level in raw coal of coal mines in some regions of China

Objective To understand the activity concentrations of natural radionuclides ⁴⁰K, ²²⁶Ra, ²³²Th, and ²³⁸U in raw coal of coal mines in some regions of China, and to explore the correlation between ore with different activity concentrations and the concentration of radon and its progeny in the workplace. Methods Raw coal samples were collected in twelve coal mines in five provinces, and the activity concentrations of ⁴⁰K, ²²⁶Ra, ²³²Th, and ²³⁸U were measured by a high-purity germanium γ-ray spectrometric system. Results The activity concentrations of four natural radionuclides in the raw coal samples of twelve coal mines were all lower than 1000 Bq/kg, and the activity concentration of ²³⁸U in one coal mine was close to 100 Bq/kg. The content of ⁴⁰K, ²²⁶Ra, ²³²Th, and ²³⁸U in different coal mines varied greatly, but ²²⁶Ra, ²³²Th, and ²³⁸U were basically at the same level in the same coal mine. Conclusion None of the 12 coal mines belong to radio active mines. One of the coal mines investigated has the activity concentrations of ²²⁶Ra, ²³²Th, and ²³⁸U close to the standard limit for restricted-use management mines. It is suggested to study the correlation between the content of ²²⁶Ra in raw ore, intermediate products, tailings(slag), or other residues and the concentration of radon and its progeny in mines. Monitoring and protection of radon and its progeny in the decay chain should be strengthened for coal mines with high activity concentrations of natural radionuclides ²²⁶Ra, ²³²Th, and ²³⁸U.