222Rn-220Rn累积探测器参加日本组织的国际比对结果分析

目的 通过参加国际比对,提高²²²Rn和²²⁰Rn累积测量的水平,保证测量的质量。方法 将本实验室的LD-P型²²²Rn-²²⁰Rn探测器寄往日本放射线医学综合研究所(National Institute of Radiological Science,NIRS),参加²²²Rn-²²⁰Rn累积探测器的国际比对。²²²Rn比对在NIRS的标准²²²Rn室进行,按暴露量分低、中、高3个水平;²²⁰Rn比对在NIRS的²²⁰Rn室进行,也分低、中、高3个水平。暴露结束后将探测器寄回本实验室进行蚀刻、分析,然后把测量结果报给NIRS,最后NIRS将暴露的参考值反馈回本实验室。结果 LD-P探测器²²²Rn比对测量低、中、高3个暴露水平的测量值与参考值的相对偏差(RPD)分别为-13.8%、-14.4% 和-17.1%;²²⁰Rn比对测量低、中、高3个暴露水平的测量值与参考值的RPD分别为-14.4%、 8.9%和-3.2%。结论 本次比对LD-P探测器²²²Rn和²²⁰Rn的测量结果均在NIRS规定的RPD为20%的一级标准范围内。     

我国非铀矿山222Rn、220Rn浓度季节变化研究

目的 研究非铀矿山中²²²Rn、²²⁰Rn浓度的季节变化规律。方法 选取云南、山东、新疆、黑龙江、湖南和贵州6个省份的铜、金、铝、锰、锑、钨、铜镍和煤矿共8类9个矿山,采用LD-P型²²²Rn-²²⁰Rn分辨探测器对井下不同季节²²²Rn和²²⁰Rn浓度进行了测量。结果 井下²²²Rn浓度存在明显的季节变化,夏季²²²Rn浓度为35.5~4841 Bq/m³,其中4个矿²²²Rn浓度均值超过1000 Bq/m³。冬季²²²Rn浓度均值为5~1917Bq/m³,只有1个矿超过1000Bq/m³。夏季与冬季的比值在2~12之间。各矿间²²²Rn浓度差异很大,通风是影响其变化的重要因素。²²⁰Rn浓度的季节变化略呈夏高冬低的趋势,由于受到布放位置的影响,其规律性有待进一步确认。结论 井下²²²Rn、²²⁰Rn浓度随季节而变化,在估算矿工受照剂量时应考虑季节变化的影响;在矿山氡测量中应避免采用瞬时测量方法;采用累积测量方法时,也应考虑季节变化的影响,合理的暴露时间应为半年,同时要注意季节的选择;对于季度性(3个月)的测量结果应该进行季节修正。     

我国非铀矿山222Rn和220Rn水平初步调查研究

目的 测量非铀矿山²²²Rn、²²⁰Rn水平,了解我国矿山氡超标比率和矿工受照剂量。方法 根据典型抽样方法选择12个省17类44座矿山,采用LD-P分辨型探测器测量²²²Rn、²²⁰Rn累积浓度。结果 ²²²Rn、²²⁰Rn浓度呈对数正态分布,金属矿(25座,147处)²²²Rn浓度算数均值(AM)和几何均值(GM)分别为(1211±2359)和(311±5.5) Bq m³;²²⁰Rn浓度AM和GM分别为(269±700)和(71±4.4) Bq m³。非金属矿(18座,118处)²²²Rn浓度AM和GM分别为(98±207)和(55±2.5) Bq m³;²²⁰Rn浓度AM和GM分别为(60±76)和(38±2.4) Bq m³。测量地下矿井40处,其中6处²²²Rn浓度均值超过1000 Bq m³ (工作场所氡浓度限值),占抽样率15.0%;约有7%测点²²²Rn超过浓度3700 Bq m³ (我国铀矿冶氡浓度限值),个别测点超过10 000 Bq m³。井下和地面工作区室内²²²Rn平衡因子分别为0.33±0.15和0.47±0.18。²²⁰Rn平衡因子的波动范围较大,为0.001～0.032。地下矿山矿工的年均受照剂量约为8.15mSv。结论 我国金属矿山特别是有色金属矿井下²²²Rn浓度偏高的问题依然严重,值得关注和进行跟踪研究。     

浙江部分地区室内222Rn和220Rn水平及剂量估算

目的 调查浙江省余杭区和三门县居室内²²²Rn、²²⁰Rn及其子体水平,明确其所致公众有效剂量。方法 采用固体径迹探测器测量余杭区和三门县两地居室中²²²Rn和²²⁰Rn浓度,探测器均放置于卧室或客厅,在不改变居民日常通风习惯情况下连续暴露6个月。结果 不同房屋类型室内²²²Rn和²²⁰Rn测定,均显示平房室内氡浓度最高。室内²²²Rn浓度与不同建筑年代无关(F =0.53, P >0.05),而室内²²⁰Rn浓度与不同建筑年代有相关性(F =3.56, P <0.05)。室内²²⁰Rn浓度未装修居室高于装修居室(t =2.33, P <0.05)。余杭区调查的居室内平均²²²Rn浓度为32.5 Bq/m³,²²⁰Rn为314.3 Bq/m³,所致有效剂量分别为0.88 和0.42 mSv;三门县调查的居室内平均²²²Rn浓度为26.8 Bq/m³,²²⁰Rn为399.5 Bq/m³,有效剂量分别为0.72 和0.53 mSv。结论 浙江余杭和三门室内²²²Rn浓度属正常天然本底水平,两地农村居室内²²⁰Rn浓度较高,²²⁰Rn及其子体的剂量贡献超过了²²²Rn及其子体引起的年有效剂量的50%。     

3H-TdR与125I-UdR掺入淋巴细胞增殖的比较

目的 比较 ³H-TdR与 ¹²⁵I-UdR掺入淋巴细胞的增殖效应。方法 用 ³H-TdR与 ¹²⁵I-UdR掺入法测定淋巴细胞和Daudi淋巴瘤细胞的增殖效应。结果 ³H-TdR和 ¹²⁵I-UdR在正常淋巴细胞中的掺入率分别为20.95%±1.06%和1.00%±0.04%,在Daudi淋巴瘤细胞中的掺入率分别为29.94%±4.10%和6.02%±0.73%。 ³H-TdR在细胞中的掺入率明显高于 ¹²⁵I-UdR;且 ³H-TdR和 ¹²⁵I-UdR在淋巴瘤细胞中的掺入率高于正常淋巴细胞。结论 就淋巴细胞而言,作为示踪剂 ¹²⁵I-UdR不能替代 ³H-TdR;但对于淋巴瘤细胞,能否代替 ³H-TdR有待于进一步研究。     

云南芒市地区野生食用蘑菇中137Cs、40K含量及所致居民剂量估算

目的 检测可食用野生蘑菇中人工放射性核素¹³⁷Cs和天然放射性核素⁴⁰K的含量及分布特点,计算野生蘑菇中放射性核素水平及其所致剂量。方法 采集了产自云南省芒市的18类33份可食用野生蘑菇样品,用实验室低本底高纯锗（HPGe）γ谱仪分析了其中放射性核素¹³⁷Cs、⁴⁰K的含量。结果 33份样品中,仅1份样品¹³⁷Cs的含量在探测限之下,其余32份样品中均可检测出¹³⁷Cs,比活度范围值为0.45~339.58 Bq/kg（干重）,平均值25.47 Bq/kg（干重）。所有样品均检测出天然放射性核素⁴⁰K,核素比活度最小值和最大值分别为453.4、1 882.6 Bq/kg（干重）,平均值为815.1 Bq/kg（干重）。当去除只有1个样品数的蘑菇种类后,毛钉菇、美味牛肝菌、白牛肝菌、锈盖粉孢牛肝菌、香菇、茶褐牛肝菌6个种类蘑菇间¹³⁷Cs含量差异有统计学意义（F=21.13,P<0.05）,而⁴⁰K含量差异无统计学意义。结论 6类不同蘑菇中¹³⁷Cs含量不同,其中毛钉菇、香菇中人工放射性核素¹³⁷Cs含量相对较高。但食入此类蘑菇对成人所致待积有效剂量极其微小,不会影响健康。     

阴离子交换树脂除210Bi技术在90Sr分析中的应用

目的 为了克服现有分析标准推荐的硫化铋沉淀法除铋存在的弊端,提升分析结果质量。方法 基于201×7阴离子交换树脂设计了除铋实验流程,并通过加标样品和国际原子能机构（IAEA）国际比对样品分析予以验证。结果 采用阴离子交换树脂进行除铋。在锶、钇、铋去除实验中,锶和钇的化学回收率可分别达到（98.6±0.8）%和（98.5±0.7）%,且未发现有Bi₂S₃沉淀生成;在加标土壤分析中,所得到的分析结果与理论值的相对标准偏差为-2.97%~5.94%,优于标准除铋方法的3.96%~17.80%;采用IAEA国际比对样品进行验证,⁹⁰Sr的报出值与目标值的相对标准偏差介于3.40%~7.09%,结果均可接受。结论 阴离子交换树脂对铋能够实现很好的定量去除,同时不吸附锶和钇。另外,阴离子交换树脂的除铋溶液体系与⁹⁰Sr分析时的解吸体系相同,无需转换体系即可实现快速除铋的目的。与现行标准分析方法相比,基于阴离子交换树脂定量除铋是可行的且更优,能够满足⁹⁰Sr常规分析工作需求。     

ICP-MS法分析尿中总铀和235U/238U比值及其不确定度评价

目的 建立电感耦合等离子体质谱（ICP-MS）快速测量尿中总铀含量和²³⁵U/²³⁸U比值的方法,并进行不确定度评价。方法 尿样经浓HNO₃和H₂O₂处理后,一部分定容直接进入ICP-MS测定总铀含量;一部分经磷酸三丁酯（TBP）萃淋树脂分离富集铀,采用ICP-MS测定其中²³⁵U/²³⁸U比值。以人尿样为例,通过样品前处理、测量、标准曲线计算,建立数学模型分析总铀及²³⁵U/²³⁸U比值的不确定度来源,进行不确定度合成。结果 该方法分析尿中总铀加标回收率为98.4%~102.4%,方法检出限为0.002 μg/L。经过不确定度评价,尿样中总铀含量的相对扩展不确定度为 0.26（k=2）;²³⁵U/²³⁸U比值的相对扩展不确定度为0.001 1（k=2）。结论 该方法加标回收率高,检出限低,精密度较好,能够实现尿中总铀的定量和²³⁵U/²³⁸U比值的快速分析,适用于放射职业照射或核应急的公众照射中尿铀及²³⁵U/²³⁸U比值的分析;尿中总铀及²³⁵U/²³⁸U比值不确定度评定结果准确可靠。     

甘肃陇东地区室内222Rn、220Rn浓度季节变化的调查分析

目的 研究我国传统住房室内222Rn、220Rn随季节变化的规律.方法 选择甘肃省陇东地区5种不同类型的传统建筑44间及普通砖瓦房5间.采用LD-P型222Rn-220Rn分辨累积探测器,按冬、春、夏、秋4个季节对室内222Rn、220Rn浓度进行测量.结果 室内222Rn浓度随季节变化而变化,不同种类房屋变化规律不同...     

56Fe17+、12C6+重离子束与60Co γ射线对人淋巴细胞染色体畸变、细胞周期

目的 比较⁵⁶Fe¹⁷⁺、¹²C⁶⁺重离子束与⁶⁰Co γ射线对人淋巴细胞染色体畸变、周期、凋亡的影响。方法 ⁵⁶Fe¹⁷⁺、¹²C⁶⁺重离子束和⁶⁰Co γ射线分别照射人淋巴细胞系Peng-EBV,吸收剂量均为0、0.5和2.0 Gy,⁵⁶Fe¹⁷⁺重离子束剂量率为0.26～0.55 Gy/min,¹²C⁶⁺重离子束剂量率为0.30～0.50 Gy/min,γ射线照射剂量率为0.75 Gy/min。研究不同射线对染色体细胞畸变率、“双+环”畸变率的影响。利用流式细胞仪检测细胞周期和细胞凋亡。结果 ¹²C⁶⁺、⁵⁶Fe¹⁷⁺重离子与⁶⁰Co γ射线照射后细胞畸变率与0 Gy相比,差异有统计学意义（χ²=12.08～322.97,P<0.05）。“双+环”畸变率与0 Gy相比,差异有统计学意义（χ²=4.06～205.37,P<0.05）。其中,¹²C⁶⁺重离子束诱导的细胞畸变率和“双+环”畸变率最高,其次是⁵⁶Fe¹⁷⁺重离子束,而且二者均高于⁶⁰Co γ射线。⁵⁶Fe¹⁷⁺、¹²C⁶⁺离子束与⁶⁰Co γ射线均能诱导人淋巴细胞发生明显的G₂期阻滞,差异有统计学意义（t=-80.9～0.17,P<0.05）,¹²C⁶⁺重离子、γ射线及⁵⁶Fe¹⁷⁺重离子诱导的G₂期阻滞程度依次降低。⁵⁶Fe¹⁷⁺、¹²C⁶⁺离子束与⁶⁰Co γ射线均能促进细胞凋亡,差异有统计学意义（t=-22.65～0.87,P<0.05）,¹²C⁶⁺重离子、γ射线及⁵⁶Fe¹⁷⁺重离子诱导的早期凋亡率依次降低。结论 ⁵⁶Fe¹⁷⁺、¹²C⁶⁺离子束与⁶⁰Co γ射线均能诱导人淋巴细胞发生明显的染色体畸变、G₂期阻滞及细胞凋亡。¹²C⁶⁺离子束诱导的染色体畸变、周期阻滞和凋亡程度最高。⁵⁶Fe¹⁷⁺、¹²C⁶⁺离子束与γ射线的生物学效应与LET相关。     

Performance test for radon measuring instruments using radon chamber at PTB

An intercomparison on radon ((222)Rn) measuring instruments was carried out at the Physikalisch Technische Bundesanstalt, Germany (PTB). Two types of alpha track detectors based on a passive (222)Rn-thoron ((220)Rn) discriminative measurement technique were used: these were the commercially available Raduet and Radopot detectors that were developed and calibrated by the National Institute of Radiological Sciences, Japan (NIRS). The (222)Rn grab sampling and continuous measurement methods were also compared using the PTB pulse ionization chamber. The results using the passive detectors showed that there was a good agreement between the time-integrated (222)Rn concentrations obtained from the Raduet detectors and the PTB pulse ionization chamber, as in the case with the Radopot detectors. In the grab sampling measurements, the agreement between the (222)Rn concentrations measured using the NIRS gas storage ionization chamber and the PTB pulse ionization chamber was within 5% as in the case with the NIRS scintillation cell measurement. Similar to the measurements of the passive detectors and grab sampling, little distinct difference in the (222)Rn concentration was observed for the NIRS continuous electrostatic collection monitor.     

International intercomparisons of integrating radon detectors in the NIRS radon chamber

An international intercomparison of integrating detectors was conducted at NIRS (National Institute of Radiological Science, Japan) with a 24.4 m³ inner volume walk-in radon chamber that has systems to control radon concentration, temperature and humidity.During the first intercomparison (05.2007) four groups participated from four countries and for the second intercomparison (10.2007) 17 participants were involved from 11 countries.Most of detectors are in good agreement with each other when compared to the radon level provided by the radon chamber. It appeared that the 70% of detectors are unified within the 20% margin of uncertainty.     

Comparison between different methodologies for detecting radon in soil along an active fault: The case of the Pernicana fault system,Mt. Etna (Italy)

Three different methodologies were used to measure Radon (²²²Rn) in soil, based on both passive and active detection system. The first technique consisted of solid-state nuclear track detectors (SSNTD), CR-39 type, and allowed integrated measurements. The second one consisted of a portable device for short time measurements. The last consisted of a continuous measurement device for extended monitoring, placed in selected sites. Soil ²²²Rn activity was measured together with soil Thoron (²²⁰Rn) and soil carbon dioxide (CO₂) efflux, and it was compared with the content of radionuclides in the rocks. Two different soil–gas horizontal transects were investigated across the Pernicana fault system (NE flank of Mount Etna), from November 2006 to April 2007. The results obtained with the three methodologies are in a general agreement with each other and reflect the tectonic settings of the investigated study area. The lowest ²²²Rn values were recorded just on the fault plane, and relatively higher values were recorded a few tens of meters from the fault axis on both of its sides. This pattern could be explained as a dilution effect resulting from high rates of soil CO₂ efflux. Time variations of ²²²Rn activity were mostly linked to atmospheric influences, whereas no significant correlation with the volcanic activity was observed. In order to further investigate regional radon distributions, spot measurements were made to identify sites having high Rn emissions that could subsequently be monitored for temporal radon variations. SSNTD measurements allow for extended-duration monitoring of a relatively large number of sites, although with some loss of temporal resolution due to their long integration time. Continuous monitoring probes are optimal for detailed time monitoring, but because of their expense, they can best be used to complement the information acquired with SSNTD in a network of monitored sites.     

Seasonal levels of radon and thoron in the dwellings along southern coastal Orissa,Eastern India

Inhalation of radon (²²²Rn) and thoron (²²⁰Rn) are a major source of natural radiation exposure. Indoor radon–thoron study has been carried out in some dwellings of Ganjam district, southern coastal Orissa, India using LR-115 type II plastic track detectors. Seasonal variation of indoor radon and thoron shows high values in winter and low values in both summer and rainy. The inhalation dose lies in the range of 0–0.06 μSv h^?1 and is not high from those found elsewhere in India.     

Indoor 222Rn measurements using an activated charcoal detector

A commercially available activated charcoal detector for measuring ²²²Rn activity concentrations in air was calibrated with known amounts of ²²²Rn and examined in terms of air luminescence counts and interferences from ²²⁰Rn and ²¹⁹Rn. The results for conditions normally encountered indoor indicate that the detector is simple and reliable. The method has been applied to assay indoor ²²²Rn activity concentrations in 387 homes in Tokyo and the adjacent four prefectures, which ranged from 0.7 to 140 Bq/m³ and averaged 22.7 Bq/m³.