某退役稀土厂环境空气中~(222)Rn、~(220)Rn子体水平及土壤析出率调查

目的了解上海某稀土化工厂周围222Rn/220Rn子体浓度及土壤析出率水平。方法用BWLM-PLUS-S氡、钍射气子体测量仪测量222Rn/220Rn子体浓度以及ERS-2氡析出率仪和RAD-7测量222Rn/220Rn析出率。结果厂区室外222Rn/220Rn子体平衡当量浓度平均值分别是1.08Bq/m3和0.06Bq/m3,室内平均值分别是8.58Bq/m3和0.09Bq/m3;车间内222Rn/220Rn子体浓度平均值是14Bq/m3和0.13Bq/m3,办公室内平均值是3.16Bq/m3和0.05Bq/m3。厂区周围6处土壤中222Rn析出率最高为63.9mBq/(m2s),最低为6.3mBq/(m2s),平均18.9mBq/(m2s);222Rn析出率最高为1.72Bq/(m2s),最低为43.4mBq/(m2s),平均0.41Bq/(m2s)。结论厂区外环境、室内中222Rn/220Rn子体浓度在世界室内外水平之下,222Rn/220Rn析出率总体处于世界土壤的平均值范围内,只在个别测点偏高。     

室内外222Rn浓度及居民所受子体照射剂量测定

目的 检测广州市室内外空气中222Rn浓度水平及其子体所致公众有效照射剂量.方法 于2003年7月～2004年6月,采用CR-39α固体径迹探测器测量广州市201间建筑物室内222Rn累积浓度,计算所致居民年有效剂量当量.结果 室内222Rn浓度范围为15.7～157.9 Bq/m3,平均值为(47.3±23.4)Bq/m3,室外222Rn浓度平均值为(20.5±8.7)Bq/m3.室内外222Rn子体所致居民人均年有效剂量当量为1.322 mSv/a,所致广州市居民集体年有效剂量当量为11 650 man·Sv/a.结论 广州市室内222Rn浓度属正常天然本底水平.     

名古屋市室内空气222Rn、220Rn的测量及EECTn估算

目的 研究室内空气中^222Rn、^220Rn浓度以及室内平衡当量^220Rn浓度EECTn。方法 利用名古屋大学研制的新型被动累积式^222Rn、^220Rn测量杯在日本名古屋市进行了小规模的室内^222Rn、^220Rn的浓度调查，利用Deposition Rate Monitor估算了住宅室内EECTn。结果 在随机抽查的20个住宅室内^222Rn平均浓度为16．94Bqm^-3；其中5个住宅室内^220Rn平均浓度为58．09Bqm^-3，EEGTn平均值为2．75Bqm^-3。结论 本研究结果与日本全国性调查结果^222Rn浓度平均值15．5Bqm^-3相当。^220Rn的浓度在某些泥土墙壁的住房内可能达到比较高的浓度，进行进一步的研究是很有必要的。     

云南省某铅矿^222Rn、^220Rn水平及γ剂量率调查

目的调查云南省某铅矿井下放射性水平,分析可采取的井下辐射防护措施。方法应用瞬时测量技术对铅矿井下不同海拔高度的五个矿洞进行222Rn、220Rn浓度和γ剂量率测量。结果井下矿区222Rn浓度中位数值为1 367 Bq/m3,220Rn浓度中位数值为24 Bq/m3,222Rn子体α潜能浓度中位数值为3.04μJ/m3,γ剂量率平均值为0.08μGy/h;不同监测矿洞的222Rn浓度分布差异有统计学意义（P﹤0.05）,220Rn浓度分布差异无统计学意义（P﹥0.05）;海拔最高的监测矿洞222Rn浓度分布与其他各个监测矿洞差异有统计学意义（P﹤0.005）,222Rn浓度低于其他各个监测矿洞;采场与井下休息区的222Rn浓度分布差异无统计学意义（P﹥0.05）、220Rn浓度分布差异有统计学意义（P﹤0.05）,采场的220Rn浓度高于井下休息区。结论铅矿井下矿区222Rn浓度超过国家标准规定的管理目标值（1 000Bq/m3）,现有井下通风系统不能有效降低222Rn浓度,222Rn浓度是220Rn浓度的50倍,222Rn子体α潜能浓度未超出国家标准规定的限值（3.57μJ/m3）,γ剂量率未超出国家标准规定的限值（1μGy/h）,均在云南省本底范围内,矿井下的工作人员应接受个人剂量监测和职业健康检查。     

中国部分地区~(220)Rn浓度的测量

目的 了解我国不同地区室内外~(220)Rn及其子体的水平及对居民所产生的有效剂量。方法 采用日本名古屋大学提供人的Rn-Tn固体径迹探测器和子体潜能法测量了室内外~(222)Rn、~(220)Rn及其子体的浓度,用UNSCEAR 1996年报告给出的~(222)Rn、~(220)Rn剂量转换系数估算了吸入~(222)Rn和~(220)Rn子体产生的年均有效剂量。对土壤中~(232)Th含量与~(220)Rn浓度的相关性及其影响因素进行了探讨。结果 北京、广州、珠海、平凉等地室内~(220)Rn及其子体的浓度分别是相似文献   

小型222Rn、220Rn室的测试分析

目的建立自制的小型~(222)Rn、~(220)Rn实验用小氡室,以进行~(222)Rn/~(220)Rn探测器设计的多项实验指标的预测试。方法使用铀镭平衡粉末标准源、钍粉末标准源,体积合适的干燥器、以及适量干燥剂制成~(222)Rn、~(220)Rn实验用小氡室,RAD7氡测量仪为其测定装置。结果"~(222)Rn-~(220)Rn混合室"内~(222)Rn浓度随时间的增加而有规律地逐渐增加,当浓度增至一定水平时不再继续增加,其浓度随累积时间的增长基本符合对数函数关系。"~(222)Rn-~(220)Rn混合室"内~(220)Rn浓度在较短的时间很快就达到较高的水平,并且随累积时间的增加没有呈现明显增加的趋势;使用RAD7测氡仪的大体积干燥器测量~(220)Rn存在明显测量延迟。结论该自制小型~(222)Rn、~(220)Rn室能够完成~(222)Rn/~(220)Rn探测器设计用的多项实验指标的预测试。     

河北省地下煤矿222Rn、220Rn水平及γ剂量率的调查

目的调查河北省唐山地区地下煤矿放射性水平。方法应用累积测量和瞬时测量技术对四个地下煤矿氡浓度和γ剂量率进行测量,以及用高纯锗γ谱仪对各煤矿的放射性核素活度浓度测量。结果对四个煤矿累积测量表明:矿区煤矿222Rn浓度约为50.1Bq/m3,220Rn约为38.4Bq/m3,矿井下γ剂量率约为108nGy/h;瞬时取样测量表明矿区煤矿中222Rn浓度约为60.8Bq/m3,矿区地表γ剂量率约为67nGy/h;煤矿中煤和矸石238U,226Ra,232Th,40K放射性活度浓度算术平均值分别为39.6,31.3,36.3,26.0Bq/kg。结论唐山地区地下煤矿氡浓度高于环境氡浓度,该矿区煤的放射性核素含量低于全国平均值,矿区归一化集体剂量4.76人mSv/万t。     

一种内源式^220Rn室的研制

目的为开展各种。^220Rn浓度测量仪器的校准，研制^220Rn室。方法基于程控式恒温恒湿实验箱，设计温度和湿度可控的内源式。^220Rn室；利用树脂吸附法制备颗粒状^220Rn源，合理设置^220Rn源并借助四个内置风扇的风速调节以实现^220Rn浓度的均匀分布。结果在同一温度和湿度条件下，^220Rn室内^220Rn浓度变化范围小于±3．0％，且在有效体积范围内（约200L），^220Rn浓度分布基本均匀（波动范围小于±5．5％）；^220Rn室内^220Rn浓度可忽略不计。结论该^220Rn室内。^220Rn浓度稳定且分布均匀，可用来开展^220Rn浓度测量仪器的校正或比对实验。     

我国居民室内钍射气(~(220)Rn)的水平

居室内钍射气(~(220)Rn)及其子体照射对健康影响越来越受到关注,我国土壤中~(232)Th含量明显高于世界平均水平,使得我国传统建材中~(232)Th含量偏高,我国还有相当数量居民房屋材料是砖和泥土,导致我国居民住房内~(220)Rn水平高于~(222)Rn。从国内外发表的有关~(220)Rn及其子体的报道,其产生的剂量可能比现在估算的世界平均值高。ICRP 50号出版物推算~(222)Rn和~(220)Rn的平衡当量浓度分别为15 Bq/m~3和0.5 Bq/m~3,所导致的肺癌增加分别为每100万人年32人和3.6人。我国不同区域的地质构造和地质断裂构造不尽相同,西北黄土高原、西南地区的个旧市以及华南地区的阳江市是有代表性的钍射气高水平地区,这三个地区室内~(220)Rn浓度水平都高于~(222)Rn,其中以黄土高原的窑洞内~(220)Rn浓度水平最高,~(220)Rn浓度最高可达~(222)Rn的9倍,窑洞中~(220)Rn及其子体所致有效剂量远高于~(222)Rn及其子体所产生的剂量。     

乌鲁木齐地区居室内222Rn及子体辐射影响研究

目的为掌握乌鲁木齐地区居室内222Rn及子体对居民的辐射影响状况,为本地区居室内222Rn污染防治提供科学依据。方法 2008年8月至2009年8月,在全市范围内进行了居室内222Rn浓度累积测量,根据测量结果估算出其所致居民年均有效剂量和部分关键人体器官与组织的吸收剂量。结果乌鲁木齐地区居室内222Rn年均浓度为57Bq.m-3,居室内222Rn及子体致居民的年均有效剂量为1.87mSv,其所致人体支气管上皮组织、肺、性腺、骨髓及骨表面细胞的年吸收剂量分别为2426.36、485.26、39.90、40.90和40.90μGy.a-1,达到了世界平均水平的1.42倍和《全国土壤氡-室内氡关联性研究》课题组10城市平均水平的1.63倍。结论乌鲁木齐地区居室内222Rn与全国相比处于较高水平,应引起高度重视。     

Time-averaged exposures to 220Rn and 222Rn progeny in Colorado homes

Week-long time-averaged exposures to naturally occurring 220Rn and 222Rn progeny have been measured at several locations in Colorado by monitoring the alpha activity collected continuously on a fixed-membrane filter. The alpha-energy spectrum associated with the activity collected on the filter was recorded every 15 min using a microcomputer-controlled alpha spectrometer. The alpha counts observed in three energy regions permitted complete separation of the contributions from each decay chain, and calculation of the separate time-averaged potential alpha-energy concentrations in air from 220Rn progeny, PAEC(Tn), and from 222Rn progeny, PAEC(Rn). The time-averaged PAEC(Tn) ranged from 0.3 to 6.9 mWL at 12 indoor locations, and the time-averaged PAEC(Rn) ranged from 1.0 to 59.0 mWL. The ratios of the indoor PAEC(Tn) to indoor PAEC(Rn) ranged from 0.09 to 0.58, with an overall average ratio of 0.32 and a standard deviation of 0.15. The 10 L min-1 flow rate through the filter was selected to approximate the air intake rate of a resting human; the time-averaged PAEC thus represents the progeny concentrations that would have been inhaled by a person breathing the same atmosphere.     

珠海市环境中^222Rn、^220Rn浓度的调查研究

目的了解珠海市室内外空气中222Rn、220Rn及其子体浓度及由此而对居民所产生的有效剂量.方法采用固体径迹探测器测量222Rn、220Rn浓度,采用α潜能法测量222Rn、220Rn子体浓度.结果珠海市室内外222Rn及其子体的浓度分别为室内60.4Bq·m-3、35.4 EECBq·m-3和室外23.4Bq·m-3、12.3 EEC Bq·m-3.室内外220Rn子体浓度分别为2.7和0.8 EECBq·m-3.222Rn、220Rn及其子体所致居民年有效剂量分别为1.62和0.61mSv.结论珠海市室内外222Rn、220Rn浓度高于世界均值,其原因与珠海地区土壤和岩石中天然放射性核素背景有关.     

Biological variability influencing lung dosimetry for inhaled 222Rn and 220Rn decay products

Particle deposition, clearance and dosimetry of inhaled short-lived 222Rn and 220Rn decay products in the human respiratory tract have been modeled by a stochastic compartment system, based on an already existing deterministic model (Ho82a). In order to allow for statistical uncertainties and biological variabilities, input parameters and transfer coefficients were described by truncated lognormal frequency distributions. Applying Monte Carlo techniques, a set of parameter values is selected randomly in an iterative manner from these prespecified distributions, yielding finally basal-cell doses as probability density distributions instead of single mean doses. The resulting highly skewed dose distributions illustrate the fact that a small percentage of individuals in an exposed population receives considerably higher doses than indicated by a deterministic mean value.     

Relationship of 220Rn and 222Rn progeny levels in Canadian underground U mines

Radon-222 and 220Rn progeny are found in some Canadian underground U mines. Because both can contribute to lung dose, their experimental determinations are important. The relationship between 222Rn progeny Working Level [WL(Rn)] and 220Rn progeny Working Level [WL(Tn)] has been investigated in U mines. Experimental measurements extended from 1981 to 1986 and consisted of about 700 measurements of each WL(Rn) and WL(Tn). The data were analyzed by standard linear and power-function regression analysis. A power-function relationship between WL(Rn) and WL(Tn) seemed to fit the experimental data best. The relationship obtained permits the calculation of WL(Tn) from experimental values of WL(Rn). The relationship is useful for lung-dose-calculation purposes and in mine-ventilation-engineering calculations.     

Relationship between the 210Pb content of teeth and exposure to Rn and Rn daughters

Existing data on 210Pb in human teeth are reviewed for various countries. The mean value of 210Pb in the teeth of population groups exposed to "normal" levels of radon-daughter exposure is about 2 mBq/g. A detailed analysis of 48 samples from a "normal" Italian population group revealed that smoking habits and age may have some influence on 210Pb content of teeth, while this is not the case for differences in sex. A group of 45 Austrians exposed to elevated levels of radon and radon daughters is compared with the Italian group. After subtraction of background levels of 210Pb as found for the normal Italian population, the incremental 210Pb tooth content due to excessive radon-daughter exposure has been correlated with the individual cumulative exposure corrected for background radon-daughter exposure. A statistical analysis shows the significance of the linear correlation at the alpha = 0.01 level. For the incremental increase of 210Pb in teeth, a value of 1.2 mBq/g has been used for a lifetime exposure to 1 WLM. This result is compared to corresponding data published in the literature, which are predominantly related to the 210Pb content of bone after short-time exposure at high levels, e.g. in uranium mines. The comparison seems to indicate the influence of the exposure rate and the need for a comprehensive model, which takes into account radon-daughter inhalation, radon dissolved in body fluids and 210Pb metabolism.