佳木斯市2004年天然辐射水平与剂量监测分析

为进一步摸清佳木斯市天然γ辐射本底水平和人群受照剂量水平及研究环境辐射对居民机体的影响,我们在1983年的基础上对佳木斯市天然γ辐射水平再一次进行了调查,这也为我市将来核能的利用和发展提供背景材料和科学依据.     

朝阳市建筑材料γ照射量率水平分析

朝阳市建筑材料γ照射量率水平分析辛彩民，王贵学，王军，孙瑞田（辽宁省朝阳市劳动卫生职业病防治所朝阳市１２２０００）朝阳地区建筑材料厂家及品种较多，为保障公众及其后代的健康，促进建材工业合理发展，根据国家《建筑材料放射卫生防护标准》，我们于１９８９年对...     

桂西山区天然环境γ辐射(本底)水平调查

目的 了解桂西山区自然环境γ辐射对当地居民健康的影响。方法 用ＦＤ－７１Ａ型闪烁辐射仪，对室内外及道路环境的５８３个测试点进行γ辐射空气照射量率测定，并估算出当地居民年均吸收剂量。结论 桂西山区属正常天然辐射地区，环境中天然γ辐射对当地长住居民健康无危害。     

宁波北仑港地表γ辐射本底调查

本文报道了宁波北仑港区地表γ射的本底调查情况，根据测量推算该地区的剂量当量率范围在0．12～0．21USV／h，并再次证实了地表γ辐射水平与地面性质的密切关系。同时也对дьг—01H型放射性监测器的使用提出了一点建议．     

思茅地区水泥厂^137Cs应用现状调查

本文对全区水泥厂使用的低活度~(137)Cs铯放射性源、10台核子称、7台料位计,分别安装于生料仓下料口、立窑下料口等生产环节的在放射源封闭及开启条件下不同方向、不同距离进行照射量率测试。结果:10台核子称源密封条件下照射量率均值和标准差范围在171.30～1048.70 uR/h±30.82～1338.56 uR/h,源开启条件下照射量率均值和标准差范围在85.95～1497.08 uR/h±137.51～2382.80 uR/h之间。7台料位控制仪源密封条件下照射量率均值和标准差范围在833.00～2239.86 uR/h±234.43～3236.24 uR/h,源开启条件下照射量率均值和标准差范围在16.02～378.43 uR/h±1.98～1577.83 uR/h之间。其结果属小剂量长期辐照场,全年累积照射量率未大于5雷姆,但提示应对放射源采取相应的屏蔽措施,以保障操作者健康安全,避免辐射损伤。     

某厂生活区居室内γ辐射水平的影响因素

目的 了解某厂生活区各种因素对居民室内γ辐射水平的影响.方法 采用国产FD-71型闪烁辐射仪对居室内γ辐射水平进行测定.结果 白涂料墙壁的居室γ辐射水平明显高于喷塑及水泥墙壁的居室γ辐射水平(P＜0.05),水磨石地板居室比其他地板居室的γ辐射水平均低(P＜0.05),水泥地板的居室γ辐射水平也明显低于地板砖及塑料地板的居室γ辐射水平(P＜0.05).结论 建议装饰居民住宅时应选取γ照射量率低的装饰材料,以减少对人体的危害.     

放射治疗外照射的蒙特卡罗计算

目的 验证MCNP程序计算γ射线的空气比释动能率及周围剂量当量率的准确性。方法 将空气比释动能率的理论计算值与模拟值进行对比,以及将周围剂量当量率的实际测量值与模拟值进行对比。结果 比释动能率的理论值与模拟值吻合良好,而周围剂量当量率的测量值与模拟值最大误差不超过7.9%,两者呈现与距离平方成反比趋势,随距离增大两者之间的误差变小。结论 MCNP程序可准确模拟空气比释动能率和周围剂量当量率,可应用于制定放疗计划和机房防护等工作中。     

佛山市放射工作人员个人剂量水平调查

本文介绍了在佛山市放射工作人员个人剂量监测的试点调查工作。结果表明：佛山市放射工作人员的年剂量当量小于5mSv95.5%，超过5mSv仅占4.5%。文中对调查结果作了分析并讨论了放射防护工作中的经验教训和改进防护措施的意见。     

南宁市医院室内氡浓度及γ辐射水平所致工作人员剂量

目的 了解南宁市医院放射科与核医学科室内氡浓度和γ照射量率水平,估算工作人员受照剂量,为辐射防护管理提供依据。方法 采用ATD累积氡探测器和FH40G环境X、γ剂量率仪测量室内外氡浓度和γ照射量率。结果 核医学、放射科地下和地面工作场所、工作人员和居民受照剂量分别是1.98 mSv、1.84 mSv、1.62 mSv、1.48 mSv和1.49 mSv。结论 核医学科工作人员受到的附加剂量主要与放射性同位素的用量与防护条件有关。放射科工作人员剂量增高的原因主要来自氡污染产生的内照射。     

加速器机房周围剂量当量率理论计算和实际测量结果的对比研究

目的 通过对加速器机房周围剂量当量率理论计算结果与实际测量结果的比较,探讨两者之间的关系及成因。方法 采用十分之一层法估算加速器机房主、次屏蔽墙外的周围剂量当量率,根据国家相关标准推荐的检测方法对加速器机房主、次屏蔽墙外的周围剂量当量率进行检测。结果 各加速器机房周围剂量当量率的实际测量结果均小于理论计算结果,主屏蔽墙周围剂量当量率的测量结果较之理论计算结果偏小30.0%~56.0%。结论 应用十分之一层法来估算加速器机房周围剂量当量率是可行的,偏安全的。     

Air-vegetation partitioning of polychlorinated biphenyls near a point source

We investigated polychlorinated biphenyl (PCB) emissions to the environment from a waste treatment and transfer facility over the course of three years. We show that the facility, which undertakes PCB waste consolidation and maintains a low-yield incinerator for products such as light ballasts, acted as a point source for the spatial distribution of PCBs in vegetation. Concurrent air and vegetation sampling was performed to study the relationship between air-vegetation partitioning and the octanol-air partition coefficient (KOA). We show evidence of equilibrium partitioning for lower-chlorinated congeners (log KOA between 7 and 8.5), kinetically limited deposition on plants for intermediate congeners (log KOA between 8.5 and 11), and particle-bound deposition for congeners with high log KOA values (> 11), consistent with the McLachlan partitioning model. From spring to autumn, heavier congeners become much more concentrated in samples farther away from the facility, possibly because of higher temperatures, which enhance dispersal of these congeners. Multivariate principal components analysis showed that PCB composition in vegetation near the emission source most closely resembled the Aroclor mixtures processed by the treatment facility.     

Assessment of the biological impact of point source discharges employing Asiatic clams

Three thousandCorbicula fluminea were transplanted for six months along a stress gradient produced by the thermal discharge of a power plant to ascertain whether Asiatic clams could be employed to monitor the biological impact of point source discharges. Water temperature at the warmest site (station 1) was between 25 and 35°C, 7–13°C above that in the river. Almost complete clam mortality was recorded here within 60 days. Water temperature at the next cooler site (station 2) was elevated 0.5–2.0°C above ambient river temperature (stations 3 and 4). Adult and juvenile clam shell and tissue growth and condition index was less here (P < 0.05) than at sites 3 and 4 where all three parameters were similar (P > 0.1). A one time measurement of juvenile clam scope for growth (SFG) also demonstrated a decreasing trend along the thermal gradient. SFG was positively correlated with juvenile clam shell and tissue growth (P < 0.01 and P < 0.05) but not with condition index (0.1 > P > 0.05).     

Beta-gamma point source on the skin problem--activity estimation and dose analysis

This paper presents the analytical approaches used and results obtained by the authors in the evaluation of the dose significance of maintaining a microscopic particle of beta-gamma emitting radionuclides on the skin for a finite time interval. The correlation of the response of a portable measuring instrument with radioactivity content of the particle is discussed along with the subsequent evaluation of dose to a limited skin area. Examples are given to show how two independent theoretical approaches were used to estimate the activity of 60Co from a single poor geometry measurement made with a thin window ionization chamber and how the results compared with empirical results from laboratory measurements on a prepared 60Co source. The application of Loevinger's point beta source dose distribution function and other dosimetric information is presented. A summary table and simplified equations to predict beta dose rates to 1 cm2 of tissue at a depth of 7 mg cm-2 for 3.7 X 10(4) Bq point isotropic sources of hypothetical beta emitters ranging in end point energies from 0.2 to 3 MeV and in atomic number from 10 to 90 are also included.     

A point source outbreak of campylobacter infection related to bird-pecked milk.

A point source outbreak of Campylobacter jejuni affected 11 children in a day nursery. Milk consumed by the children was known to have been pecked by magpies on occasions. Illness was significantly associated with consumption of milk on a single morning. Examination of milk from a bottle pecked after the outbreak yielded campylobacters. The level of contamination was approximately six cells of C. jejuni per 500 ml of milk.