某铀矿冶设施退役前后氡浓度调查及剂量评价

采用RAD7电子测氡仪对某铀矿冶设施退役前、过程中及退役后氡水平进行了调查,并估算了氡子体所致成年人有效剂量。结果表明,退役前、过程中和退役后该铀矿冶设施厂区氡浓度平均值分别为（35.5±3.8）Bq/m3～（38.7±4.1）Bq/m3、（14.8±2.2）Bq/m3～（84.9±6.8）Bq/m3和（10.6±1.6）Bq/m3～（11.4±1.7）Bq/m3。厂区内氡浓度退役前接近本底水平上限且数值稳定;退役过程中呈先增后减趋势,高于本底水平;退役后达到本底水平且数值稳定。该设施场所退役前、中、后氡子体照射所致成年人平均年有效剂量分别为0.97 mSv、1.34 mSv和0.27 mSv。     

厦门市土壤氡浓度水平及其分布规律调查

为获得厦门市的土壤氡浓度水平及其分布规律,使用FD-3017型RaA测氡仪,于2009年5月4日—5月12日对厦门市土壤氡浓度进行布点测量,对实测的100个数据进行统计分析并绘制土壤氡浓度等值线图。结果表明,厦门市土壤氡浓度范围为450～40 800 Bq/m3,平均值为7 538 Bq/m3;同安区的土壤氡浓度水平较高;不同类型土壤中氡浓度不同,粉质黏土土质和干硬性地表形态测量的土壤氡浓度较高。     

北京市地铁站台及车箱内氡浓度水平调查

地铁作为城市公共交通系统的重要组成部分,发挥着越来越大的作用.由于地铁所处地下环境的特殊性,其空间氡浓度水平及其对健康的可能影响受到越来越多的关注.本文介绍了近年北京市地铁氡浓度监测与调查工作的开展情况,汇总了地铁站与车箱内的氡浓度监测结果,分析了地铁工作人员与日常乘地铁出行公众的受照剂量水平,并提出了今后对地铁环境氡...     

The Effect of Some Soil Characteristics on Soil Radon Concentration and Radon Exhalation from Soil Surface

To find out the impacts of soil characters on radon concentrations in soil and radon exhalation from soil, field measurements on soil radon concentrations (60 cm under the soil surface) and radon exhalation rate from soil surface were carried out in totally 31 points with different types of soil in three cities in both South and North China. Soil radium contents, water contents, soil porosity and grain size were concretely analyzed in our laboratory. The linear simulation was used to analyze the above data. The results showed that radon exhalation rate from soil and radon concentrations in soil have direct proportion to soil radium contents. Rather high radium content and radon exhalation rate were measured in Guiyang area, 67±28Bq/kg and 40±59mBq/m²-s, however no high soil radon concentration was found due to the difficulties in the measurements on clay soils with high water saturation. Compared with soil radium contents, radon exhalation rate from soil and soil radon concentrations are more easily impacted by soil characters and change in a rather large range.     

成都地区室内氡浓度调查

采用固体核径迹法,对成都市不同建筑类型、建筑结构、装修材料以及不同楼层的100间居室进行了室内氡浓度测量。调查结果表明:成都市居室环境中氡浓度的最高值为177.1 Bq/m3,最低值为8.4 Bq/m3,算术平均值为(39.4±22.9)Bq/m3;不同类型房屋室内氡浓度水平有显著差异;氡及其子体照射所致的人均年有效剂量为0.99 mSv,低于世界平均水平。     

密闭空间氡气浓度变化规律与估算方法研究

目前在氡气研究领域中对氡气析出率的研究较为深入,但对氡气反扩散讨论和研究还较少。本文讨论了在密闭空间条件下氡气浓度计算的理论方程,并讨论了氡气反扩散对氡气浓度的影响,同时开展密闭空间实验,对集氡罩内氡气浓度进行连续测量。基于实验数据讨论氡气反扩散,通过理论方程与实测数据比较,验证氡气浓度与析出率、反扩散系数之间的关系,研究结果可为室内或矿井内等密闭空间中氡气浓度分析和估算提供参考。     

室内氡浓度及其控制措施

在不同时期,对不同建筑类型的建筑物,北京砖混房居室及办公室的室内氡浓度进行了监测,年平均氡平衡当量浓度分别为10．9,10．0,15．9Bq/m^3。估算了氡所致有效剂量为0.67mSv,略低于世界平均水平。对于室内氡含量较高的情况,提出控制措施。     

低射气介质地区浅部土壤氡气迁移规律研究

以内蒙古乌兰察布低放射性地区所测氡浓度作为分析对象,运用分形理论,提出了氡浓度分形分析法,得到在坑深30～60 cm范围内氡浓度分布的分形规律和分形维数。结果表明,不同坑深下,氡气分布具有很强的自相似性,符合分形规律,且分形维数在坑深40 cm左右达最小值。氡气浓度均值变化系数定量地表征了不同坑深下氡浓度变异程度,得出坑深40 cm左右变化率最小,分布相对稳定。两种方法相结合表明,野外测氡时,坑深取40 cm效果较好。     

氡通过不同滤膜的扩散系数测量研究

基于气体透过滤膜的扩散原理,对应用于固体核径迹探测器累积测氡的三种滤膜在四种不同湿度下的氡扩散能力进行研究。实验结果表明:醋酸纤维滤膜和普通滤纸的扩散能力明显强于PE滤膜,更适用于固体核径迹测氡,且湿度对三种滤膜氡扩散能力的影响不明显。通过本次实验得到,醋酸纤维滤膜的扩散系数为1.46×10~(-9)m~2/s~2.59×10~(-9)m~2/s,普通滤纸的扩散系数为1.01×10~(-9)m~2/s~1.45×10~(-9)m~2/s。     

The Levels of Indoor Thoron and Its Progeny in Four Areas in China

Small surveys on thoron, radon and their progeny were carried out in four areas in China. Both high thoron concentrations near to walls and high thoron progeny concentrations were found in some dwellings through the surveys. It is suggested from the limited data that attention shall be paid to the exposure from the inhalation of thoron and its progeny in some kinds of dwellings or areas, and much works on thoron study in detail is necessary.     

土壤潜势氡浓度快速测量方法理论模型的建立与验证

与室内氡水平直接相关的是土壤潜势氡浓度（土壤中潜在的最大氡浓度）,其直接测量深度通常需数米,测量非常困难,需探索快速获得土壤潜势氡浓度的方法。本工作通过对土壤氡运移规律的深入研究,建立了一个由土壤浅层氡浓度和土壤表面氡析出率确定土壤潜势氡浓度（双源法）的理论模型,并加以实验验证。实验证明了该理论模型的可靠性。该理论模型的建立为土壤潜势氡浓度快速测量方法的进一步研究奠定了基础。     

AlphaGUARD在主/被动模式下对~(222)Rn体积活度的响应

AlphaGUARD是目前技术性能最优的测氡仪之一,常用作氡测量传递标准。文章介绍了AlphaGUARD主动与被动测量模式的原理,对AlphaGUARD在主动和被动两种工作模式下和不同采样流速下的氡体积活度响应作了分析对比,实验结果表明:主动模式下AlphaGUARD体积活度响应小于在被动模式下,采样流速对AlphaGUARD的体积活度响应无明显影响;AlphaGUARD对222Rn体积活度的测量重复性随222Rn体积活度的增大而减小,但是尚得不到其重复性随采样流量的变化规律。     

气溶胶对氡室氡浓度影响的探讨

通过实验测试往氡室中充入气溶胶对氡室氡浓度的影响,及测试在不同氡浓度及气溶胶浓度的条件下气溶胶对氡子体的吸附.实验结果显示:气溶胶对氡室氡浓度的稳定性没有影响,不同气溶胶浓度则会改变氡子体的结合状态,从而影响氡子体的扩散系数,所以会影响总量测量仪的测量结果.     

我国部分地区室内外氡水平及其剂量评价

本文汇总了我国部分地区室内外氡浓度调查结果,特别指出了铀矿区附近、煤渣砖和石煤渣砖建筑物、窑洞、地下室及高本底地区室内的氡水平。确定了剂量评价中所采用的氡子体暴露量-有效剂量转换因子、平衡因子及室内停留因子,给出有效剂量估计值,最后,简单讨论了有关室内氡的防护问题。     

新风换气对室内氡浓度的影响

使用RAD7测氡仪对氡模拟实验房进行氡浓度连续测量,研究不同新风换气率对室内氡浓度的影[JP2]响。结果表明：氡模拟实验房内氡浓度最高可累积至2 000 Bq/m³,墙面平均氡析出率为14.5 Bq·m^-2·h^-1;氡模拟实验房在连续均匀地通入新风情况下,室内氡浓度随时间呈指数递减趋势;当新风换气率变化时,氡模拟实验房内的平衡氡浓度和平衡时间随新风换气率的增加呈指数递减趋势;当新风换气率由大变小时,室内氡浓度会再次累积增加。     

DSZ-3型标准氡室的研制及性能测试

报道DSZ-3型标准氡室的研制及性能测试工作。DSZ-3型标准氡室实现了在3个氡浓度区间的独立运行、氡浓度自动控制、氡室内温、湿度自动控制。性能测试结果表明：主要技术参数达到了设计要求,氡室氡浓度空间均匀性、长时间稳定性、密封性能符合国家有关标准要求,系统运行良好。     

Airborne Radon-222 Measurement by Active Sampling with Charcoal Adsorption and Gamma-Ray Spectrometry

A simple method for measuring radon concentration in air is presented. Airborne radon is adsorbed in a charcoal bed by an active air sampling. In time, the adsorbed radon comes to attain radioactive equilibrium with its short-lived progeny ²¹⁴Pb. Utilizing this fact, radon concentration is derived from γ-ray measurement of ²¹⁴Pb. This method is estimated to be capable of detecting radon concentration in air down to 0.79Bq·m^?3 The adsorption coefficient obtained with the method is compared with what is obtainable with passive sampling. Applications of this method to indoor and outdoor radon measurements are described.     

连续测氡方法迭代修正因子的理论计算与实验测定

研究了一种连续测量环境氡浓度的方法,该方法需确定前次测量对当次测量的影响,即迭代修正因子。推导了适用于上述连续测氡方法的迭代修正因子的理论公式,并计算了迭代修正因子的理论值。用基于上述方法研制的NRL-1型氡连续测量仪进行了迭代因子的测量,并对测量结果的影响因素进行了讨论。结果表明,理论计算结果与实验测量结果符合较好,迭代修正因子仅与取样时间和测量时间有关。     

A practical soil radon （^222Rn） measurement method

<正>Soil radon measurement of high stability and sensitivity is widely applied,and in some applications,such as in uranium prospecting,~(222)Rn should be distinguished from ~(220)Rn.To meet this requirement,a practical method based on soil radon diffusion and accumulation theory to measure soil radon by Alpha Particle Spectroscopy(α-PS)is discussed in this paper.Theα-PS measurement method can effectively overcome the effects of ~(220)Rn and its daughters (~(216)Po,~(212)Bi,~(212)Po).The system can eliminate the impact of soil radon field disturbance and non-uniformity through soil radon static diffusion.Radon daughters(~(218)Po,~(214)Po)are accumulated under the action of an electrostatic force, which not only enhances the measurement sensitivity,but also increases robustness of the measurement.Simultaneous measurement of multiple points can increase the comparability of measurement data and the measurement efficiency. Experimental data shows that the soil radon measurement method was robust.So it has wide applications such as in geological prospecting,in fissure groundwater exploration and in ground subsidence inspection.     

Radon Emanation Phenomena: A Probabilistic Basis to Estimate Radon Emanation Coefficients Based on Its Zigzag Travel

Previous theoretical approaches based on mathematical models by other researchers to the subject of radon emanation assumed straight linear travel of radon generated in grains constituting rocks or soils. However, it is difficult for these approaches to explain high radon emanation coefficients for rocks or soils without the introduction of the ideas of radon indirect recoil or a threshold for imbedding into grains. Unlike them, the present authors proposed anotherhypothesis based on the idea of radon zigzag travel and elucidated high radon emanation in a previous paper. The radon zigzag travel is caused by many collisions of radon with atoms constituting the grains. The results of the theoretical calculation successfully supported the claims of nanopore presence by Rama and Moore and radium layer presence near grain surfaces by Krishnaswami and Seidemann in a unified manner. However, the present authors think there is still room to improve their theory and they want to entice researchers toward a better explanation of high radon emanation for rocks or soils. Therefore, they give a probabilistic basis for their hypothesis and make a comparison between radon emanation coefficients obtained on straight linear and zigzag travel models, before concluding with a validity check of the models.