Measurement of natural radioactivity in sand samples collected from the Baoji Weihe Sands Park, China

The activity concentrations and the gamma-absorbed dose rates of the primordial naturally occurring radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K were determined for sand samples collected from the Baoji Weihe Sands Park, China, using γ-ray spectrometry. The natural radioactivity concentration of sand ranges from 10.2 to 38.3 Bq kg⁻¹ for ²²⁶Ra, 27.0 to 48.8 Bq kg⁻¹ for ²³²Th and 635.8 to 1,126.7 Bq kg⁻¹ for ⁴⁰K with mean values of 22.1, 39.0 and 859.1 Bq kg⁻¹, respectively. The concentrations of these radionuclides are compared with the typical world values and the average activity of Chinese soil. The measured activity concentration of ²²⁶Ra and ²³²Th in sand is lower than the world average while that of ⁴⁰K is higher. . To evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity, the external hazard index, the absorbed dose rate, and the effective dose rate have been calculated and compared with internationally approved values. The radium equivalent activity values of all sand samples are lower than the limit of 370 Bq kg⁻¹. The values of the external hazard index are less than unity. The mean outdoor air absorbed dose rate is 69.6 nGy h⁻¹ and the corresponding outdoor effective dose rate is 0.085 mSv y⁻¹.     

航空伽马能谱测量在突发核事件中的应用

航空放射性测量由于其独特的优点,在区域环境辐射测量、突发核事件测量等方面具有广泛的应用前景,通过一些实例来展现航空放射性测量在突发核事件测量中的优势,讨论了制定航空放射性应急测量预案的可行性。     

Resuspension of radioactive fall-out from the soil surface and particulate contamination of vegetative cover

A method for the determination of resuspension parameters of radioactive fall-out from nuclear explosions, deposited on soil from the stratospheric reservoir, is presented. The seasonal variation ofk -¹³⁷Cs resuspension parameter, the trend ofk with time in 1963–1978, the trend over this period of time of the wind component fraction of the concentration of global¹³⁷Cs in the surface boundary layer over arable and natural soils are given. An estimate of radioactive contamination of vegetation by the effect considered is given as an example of practical use of this work.     

江西相山地区航空放射性钾增量异常特征及其地质成因探讨

本文基于航空放射性K能谱数据再开发,结合野外地质调查、显微岩石学、元素地球化学等手段,分析并探讨了相山火山盆地航空放射性钾增量异常特征及其地质成因。研究表明,相山地区钾增量正值域与负值域呈NE带状相间分布,其空间延伸方位与地层的走向不一致,表现出跨地质单元现象,反映了增量场受断裂构造控制以及成岩后热液改造的基本属性。不同地质体钾含量存在差异,然而与正常未蚀变岩石比较,与铀成矿作用相关的水云母化蚀变岩石中的钾增量值表现出相对降低的趋势。钾增量亏损场(带)的形成与成矿流体在蚀变过程中具有"去钾"作用相关,是水云母交代钾长石作用的结果。铀矿床的定位与钾增量相对亏损场(带)具有良好的对应关系。根据钾增量相对亏损场可以大致圈定水云母化蚀变场,进而确定成矿流体活动范围,为铀成矿远景预测提供较为可靠的信息。     

河北宽城蛇纹石玉的宝石矿物学特征研究

河北宽城蛇纹石玉结构细腻,颜色可呈肉红色、绿色,当地市场称之为"热河玉"。本文通过常规宝石学测试结合激光拉曼光谱、电子探针、X射线粉晶衍射、激光剥蚀等离子质谱以及可见光吸收光谱等手段对其进行了系统分析,并采用伽玛能谱仪对其放射安全性进行了检测。结果表明,肉红色样品折射率及相对密度值均较低,折射率为1.54~1.55,相对密度为2.33~2.43,主要组成矿物为斜纤蛇纹石,主要具纤维交织结构、纤维柱粒交织结构,局部可见变余生物骨架结构,次要矿物有方解石和透辉石,Fe和Mn元素含量相对较高,Fe元素含量范围在184.9×10^-6~951.7×10^-6,Mn元素含量为106.4×10^-6~287.3×10^-6;绿色样品折射率为1.55~1.56,相对密度为2.58~2.62,主要组成矿物为叶蛇纹石,具更加细腻的纤维交织结构,次要矿物为滑石及四方硫铁矿,Fe元素含量极高,可达5 979×10^-6~6 359×10^-6。结合可见光吸收光谱分析结果认为Fe³⁺、Fe²⁺以及Mn³⁺的综合作用是导致样品呈现肉红色的主要原因,而Fe²⁺和Fe³⁺则是导致绿色的主要原因。放射性检测结果显示样品的内、外照射指数及放射性比活度值均低于标准要求,对人体无放射性危害。