Uptake~of U-and Th-series radionuclides by cerral crops in Upper Egypt

The main aim of this study is to determine the activity concentrations of uranium series and thorium series radionuclide in crops cultivated in Upper Egypt. Fifteen types of cereal crops were collected from local markets and analyzed by γ-ray spectrometry. The mean activity concentrations of the natural radionuclides 238U, 226Ra and 232Thdifferent age groups.     

牦牛坪稀土矿区土壤天然放射性水平评价

利用γ能谱仪对牦牛坪稀土矿区土壤的天然放射性核素进行了现场测量,计算了γ射线空气吸收剂量率和年有效剂量,并与白云鄂博稀土矿区以及广东下庄铀矿田进行对比。研究结果显示,该地区土壤中放射性核素238U、232Th和40K的含量,分别为52.36(5.55~201.06)Bq/kg、122.33(38.04~723.70)Bq/kg、1 010.09(125.20~1 705.85)Bq/kg;γ射线空气吸收剂量率平均值177.16 Gy/h,高于全国(81.50 n Gy/h)和世界(80.00 n Gy/h)的平均值,也高于白云鄂博稀土矿区(120.00 n Gy/h)以及广东下庄铀矿田(124.00 n Gy/h)的平均值。但γ外照射有效剂量在国家标准限量控制的范围内,因此,研究区天然放射性水平尚属正常范围内。该地区稀土的开采利用造成土壤天然放射性水平较高;大面积出露上三叠统冕西花岗岩体,导致研究区土壤的天然放射性水平高于白云鄂博稀土矿区以及广东下庄铀矿田。     

土壤和水中放射性核素实验室间测量比对

介绍了2015年度由本实验室组织的关于土壤和水中放射性核素实验室间测量比对的相关情况。土壤分为掺标土壤和实际土壤两类,水为掺标样品。掺标样品的比对项目包括³H(土壤中不分析)、⁹⁰Sr、⁶⁰Co、¹³⁴Cs和¹³⁷Cs,实际土壤的比对项目包括²³⁸U、²³²Th、²²⁶Ra、⁴⁰K、⁹⁰Sr和¹³⁷Cs。8家单位(11个实验室)参加了本次比对活动,比对结果整体良好。针对比对活动中发现的问题进行了分析,并对以后的比对活动提出了建议。     

Level of natural radionuclides in foodstuffs and resultant annual ingestion radiation dose

The natural radioactivities in three major groups of foodstuff widely consumed in Upper Egypt were determined. The specific activities of ^226Ra, ^232Th, and ^40K in cereals, leguminosae, and flour were measured using γ-ray spectroscopy. Another group of hay, water, and soil samples from the same location were also analyzed. Hay samples were found to contain the highest radioactivity concentration among all the samples that were investigated. This increment could be due to the high water content in the shoots which tends to accumulate soluble radionuclides. The average calculated concentrations of soil samples in the present study exhibits the lowest values with respect to those from different countries. In the case of water samples, the average activities of both ^232Th and ^40K were similar to those for soil while ^226Ra was twice that of water sample. The annual ingestion dose from each radionuclide was calculated. The computed annual dose owing to daily intake of radium, thorium, and potassium via wheat flour, lentils, and bean in the present study （214.8 μSv） is ten times lower than the global average annual radiation dose （2400 μSv） from the natural radiation sources as proposed by UNSCEAR. The obtained results show that the dose values are quite low and carry insignificant radiation dose to the public.     

浅议公众照射中婴儿的辐射剂量评价

在正常照射情况下,基于3个月和1岁婴儿以及胎儿/母乳喂养婴儿等不同年龄婴儿的剂量系数和生活习性,对婴儿摄入放射性核素的照射剂量进行了比较与分析。结果表明,采用1岁婴儿的剂量系数和生活习性,用于评价婴儿年龄组(<1岁)预期受照的年有效剂量是合适的,可以代表婴儿年龄组(<1岁)中受照剂量较高的一组婴儿。     

Measurement of natural radionuclides in bricks and brick-making clays from Cuddalore district,Tamilnadu,India

In India,bricks as building materials are mainly prepared by clay using the deposited sediments of rivers,and the radionuclide contents in bricks and brick-making clays should vary with origin and geological condition.In this paper,the radionuclide contents of these materials from river bank areas of Cuddalore district,Tamilnadu India are measured by gamma ray spectrometer using Nal(Tl) detector,and compared with those of other countries.The radiation hazard indices,which are evaluated by radium-equivalent (Raeq) activity,are lower than that of NEA-OECD.     

Gamma-ray measurements of natural radioactivity in sedimentary rocks from Egypt

The aim of this study was to measure concentrations and distributions of natural radionuclides occurring mentary rock samples from Eastern Desert (Um El-Huetat), Nile Valley (Gebel Owina) and from southwest Sinai (Wadi Ghweiba) were measured using a high-purity germanium detector. The samples under investigation (clay, shale and sandstone) were used as raw materials in the construction industry (bricks, ceramics, cement, fillers, etc.). Though the sediments of Egypt have already been investigated in the geological and mineralogical aspects, it is necessary to investigate the natural radioactivity in order to complete their classification. The average concentration values of 226Ra, 232Th, 40K in the surveyed samples were 47 ± 7,21± 5, 393±19 Bq.kg-1 (clay); 23 ± 5, 30 ± 6, 563 ± 24 Bq.kg-1(shale); and 17 ± 4, 14 ± 4, 299 ± 17 Bq.kg-1 (sandstone), respectively. All sediment samples have radium equivalent natural radionuclides present in the samples have been computed and compared with the global averages. In terms of the radiation safety, the natural radioactivity of the sediment in Egypt is below the recommended limits of the gamma dose rate. Therefore, they can be used for all kinds of public buildings.     

Assessment of radioactivity levels in some oil samples from the western desert, Egypt

Distributions of natural gamma-emitting radionuclides were determined in 93 oil samples collected from some petroleum fields in the western desert of Egypt. The radioisotope activities in the area under investigation lay in the range of (21 ± 4) to (38 ± 13) Bq?L-1 for 226Ra, (9 ± 2) to (15 ± 5) Bq?L-1 for 232Th, and (154 ± 28) to (303 ± 54) Bq?L-1 for 40K. The mean values were 27, 12, and 201 Bq?L-1, respectively. Among oils, variations in radionuclide ac- tivities could be on account of differences in TDS, HCO3, and Ba, with high or low pH. In this environment, oil prop- erties differently affected the mobilization of natural radionuclides. The range of 226Ra variation had been compared with available data from other countries. The calculated absorbed dose rate ranged from 22.33 to 32.66 nGy?h-1 in lo- cation (B) and (E) respectively, which was less than the accepted value.     

伴生放射性铁矿中放射性核素的γ能谱测量影响因素研究

利用无源效率刻度软件Angle 3.0模拟分析了铁矿石组分、装样密度及装样高度对探测效率的影响,并用掺铁标准源进行了验证。结果表明,铁元素对低能区探测效率影响显著,在组分未知时,238U的测定采用1001 keV比63.3 keV好。装样时,装样高度保持一致。装样密度与探测效率呈线性关系,在样品与标准源密度不一致的情况下,可以通过密度修正计算效率。     

广东省铀矿山周围环境样品的天然放射性核素水平监测

本文报道2013—2015年广东省环境辐射监测中心采用γ能谱法对广东省内铀矿山周围气溶胶、稻田土、菜地土、河底泥、稻谷、青菜等环境样品中天然放射性核素(²¹⁰Pb、²³⁸U、²²⁶Ra、²³²Th、⁴⁰K、⁷Be等)的监测结果。     

包头市天然放射性环境调查与评价

对包头市城区陆地γ辐射空气吸收剂量率和空气中氡、气土及其子体浓度进行了测量。其中γ辐射空气吸收剂量率瞬时测量平均值为62.5 nGy/h,累积测量平均值为100.7 nGy/h,累积剂量扣除宇宙射线响应值后与瞬时剂量结果一致,与包头市2006年航测结果值(60 nGy/h)相当。气溶胶中氡子体α潜能值12.88 nJ/m³,气土子体α潜能值9.55 nJ/m³,两种子体的α潜能值均在标准限值范围内。通过对照射剂量估算,城区外照射年有效剂量为0.58 mSv,内照射年有效剂量为1.29 mSv,数值略高于全国和世界平均水平,在同水平范围内。包头市城区放射性环境有效剂量未超过规定限值,不会对公众健康造成不良影响。     

2012—2018年度重庆市某医院放射诊疗工作人员职业照射个人剂量监测与评价

采用职业性外照射个人剂量常规监测方法,对重庆某医院放射诊疗工作人员职业性外照射个人剂量进行了监测。监测结果显示,该院2012-2018年度放射诊疗工作人员职业性外照射人均年有效剂量为0.3~0.8 mSv,远低于国家标准中职业照射人员的年剂量限值规定;职业类别年有效剂量,介入放射学>放射治疗>核医学>放射诊断。     

青岛市地表天然放射性水平及其主控因素特征

通过对青岛市1 500 km2范围内大密度土壤放射性核素(238U、232Th和40K)和地表γ辐射测量,系统深入地研究了其放射性特征、分布规律及其影响因素.结果表明,青岛市土壤中核素232Th和40K的放射性比活度偏高,而2388U偏低.地表γ辐射吸收剂量率(平均值91.87 nGy· h-1)略高于全国和世界平均值,研究发现地表93.14％的γ辐射来自地面放射性核素238U、232Th和40K的γ辐射,其中232Th和40K的贡献占81.21％,是主要的贡献者.地质背景是影响地面γ辐射吸收剂量率的主要因素,燕山期各类花岗岩是导致青岛市区—王哥庄一带γ辐射吸收剂量率偏高的主要原因;同时环境因素(路面材料、地貌景观)对地表γ辐射吸收剂量率也存在一定影响.虽然研究区的γ辐射吸收剂量率较高,但其年有效剂量(0.56 mSv)远低于公众照射年剂量当量限值1.0 mSv,人居环境基本不受影响.     

Estimating internal dose coefficients of short-lived radionuclides in accordance with ICRP 2007 recommendations

For radiation protection in high-energy accelerator facilities, internal dose coefficients of short-lived radionuclides were estimated using the dosimetric methodology in accordance with the International Commission on Radiological Protection (ICRP) 2007 Recommendations. A computational program was developed for estimating the dose coefficients. The program was verified by confirming whether it could reproduce the dose coefficients provided by ICRP for intakes of representative radionuclides. In addition, the estimated dose coefficients of short-lived radionuclides were compared to the values generated by Dose and risk CALculation software (DCAL), which is based on a dosimetric methodology that is in accordance with the ICRP 1990 Recommendations, to discuss the reasons why the dose coefficients were changed by the revision of the dosimetric methodologies. The comparison revealed a decreasing trend of dose coefficients in the case of inhalation upon revision of the dosimetric methodologies. By contrast, in the case of ingestion, the dose coefficients tended to increase.     

某核电厂2018年度个人剂量监测

介绍了某核电厂职业照射监测的方法和质量控制措施,从个人剂量的监测人数、剂量范围、人员平均剂量、大修剂量、专业剂量等方面分析了2018年度某核电厂职业照射监测结果,为核电厂个人剂量监测与控制提供参考。     

安徽省歙县石煤矿区天然放射性环境调查

对安徽省歙县石煤矿区开展了γ辐射空气吸收剂量率、空气氡活度浓度的测量,并系统采集了土壤、岩石、石煤、煤渣、煤矸石、水系沉积物等固体环境介质及地表水、地下水样品。结果表明,区内γ剂量率平均值为121.5 nGy/h,远高于安徽省和全国背景值,γ辐射水平受地层/岩性的控制,高值点集中在石煤矿山。室内、外氡活度浓度均值分别为116.8 Bq/m³、47.1 Bq/m³,显著高于背景水平。石煤、煤渣、煤矸石、碳化砖中²³⁸U和²²⁶Ra的含量较高,且碳化砖内、外照射指数超过建筑材料放射性核素限值标准,严禁作为主体建筑材料使用。石煤的私自开发造成周边河段放射性核素浓度明显增加,矿坑水中总α超过污水排放限值,应加强监管。     

中国燃煤发电排放的放射性环境影响评价研究

选取不同装机容量等级的典型燃煤机组作为研究对象,按照不同地理区域划分滨海北方、滨海南方、内陆北方、内陆南方等4个评价区,采用一批新的调查数据和参数,评价当前我国燃煤发电排放的放射性环境影响。结果表明:(1)全国燃煤电厂放射性排放所致80 km范围公众的归一化集体剂量平均值为2.2人·Sv/GWa。(2)小火电机组所致剂量约为6.0人·Sv/GWa,主流燃煤机组约为1.8人·Sv/GWa,小火电机组是主流燃煤机组的约3倍。(3)剂量贡献最大的核素是²¹⁰Po,其次是²¹⁰Pb。食入和吸入内照射是主要照射途径。(4)不同燃煤电厂周围的人口密度差别很大,使得集体剂量相差可达1个数量级。基本结论:与天然辐射源所致公众照射剂量相比,燃煤发电的辐射环境影响仍然很小;煤电的辐射环境影响是核电的34倍。淘汰小火电机组、实施超低排放改造,我国燃煤发电所致公众归一化集体剂量仍有进一步降低的空间。目前电厂除尘技术难以高效去除和有效控制²¹⁰Po排放,有必要进一步研究。     

EDXRF方法在土壤重金属污染评价中的应用

高灵敏度CUT-3000型能量色散X射线荧光(EDXRF)分析仪采用低能X光管和同位素源双激发方式，以电致冷半导体探测器作为探测系统，使该分析仪具有分辨率高、检出限低、分析元素多的特点。采用该仪器成功地分析了攀枝花地区土壤中重金属的含量，评价了该区土壤重金属污染的特征，结果表明该区重金属污染主要与工矿活动有关。     

Estimation of Dosimetric Parameters from Inhaled Activity Distribution in Human Body

A method is proposed to estimate parameters for dose calculation from inhaled activity distribution in the human body.

Inhalation of ⁶⁰Co aerosols is simulated by the metabolic model proposed in ICRP Publication 30. The ranges of parameters for dose calculation are as follows: particle size 1 to 20 μm; inhalation class Y; time after inhalation 1 to 90 d. The ratio of radionuclide retentions in the lower to upper bodies, divided by the diaphragm, is used as the index of activity distribution in the body. The results of computer simulations show that the retained activity ratio is valid to estimate intervals of possible values of particle size and time after inhalation.