Measurement of Natural Radioactivity in Lagoon Sands Used in Construction in the District of Abidjan, Côte d’Ivoire

Sand is an important natural material for the construction of houses, work buildings and other public spaces. This work, which is one of the first contributions to the environmental quality of construction materials, concerns the measurement of natural radioactivity in the lagoon sands collected in the district of Abidjan. Nineteen (19) samples of these sands are analyzed by gamma-ray spectrometry equipped with HPGe detector. The mean values obtained for 226Ra, 232Th and 40K are respectively 7.76 ± 1.84 Bq·kg-1, 5.21 ± 1.36 Bq·kg-1, and 217.31 ± 5.03 Bq·kg-1. The estimated average value of radium equivalent (Raeq) is 31.94 Bq·kg-1. The results show that the average values obtained are far lower than the global limits of 35, 30, and 400 Bq·kg-1 for the concentrations of 226Ra, 232Th and 40K, respectively, and 370 Bq·kg-1 for the equivalent radium established by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Therefore, the use of the analyzed lagoon sand samples in the different construction sectors should not cause serious radiological effects on the populations living in the District of Abidjan. Our results provide new data on building materials radioactivity in Côte d’Ivoire and all over the World. They can also be used as a reference for future work.

Environmental Radiation Measurement and Assessment of Natural Radioactivity in Soil, Water and Vegetation

Environmental radioactivity is produced by radioactive materials in the human environment. While some radioisotopes, such as strontium-90 (90Sr) and technetium-99 (99Tc), are only found on Earth as a result of human activity, and some, like potassium-40 (40K), are only present due to natural processes, a few isotopes, e.g. tritium (3H), result from both natural processes and human activities. The concentration and location of some natural isotopes, particularly uranium-238 (238U), can be affected by human activity because of the constant exposure of Human beings to radiation caused by terrestrial, extra-terrestrial and anthropogenic radio nuclides, it is necessary to determine and estimate the activity of various radio nuclides in environmental media such as vegetation, soil, and water. In the present research, the activities of 226Ra, 232Th and 40K are measured in soil, vegetation and water samples, collected from Yangdong District, Yangxi County, and Yangjiang County of Guangdong Province, China using an HPGe based gamma spectrometry system. The measured mean activity of 226Ra, 232Th and 40K in soil samples was found to be 31.19 ± 1.2, 47.00 ± 2.30 and 589.31 ± 17.52 Bqkg-1, respectively. The measured mean activity of these radionuclides in all water samples was found to be below minimum detectable activity. The measured mean activity of 226Ra, 232Th and 40K in vegetation samples was 19.92 ± 3.09, 25.36 ± 8.11 and 4982.94 ± 85.68 Bqkg-1, respectively. No anthropogenic 137Cs was detected in these environmental samples. Mean radium equivalent activity (Raeq), external radiation hazard index (Hex), internal radiation hazard index (Hin) and absorbed dose rate (D) for the area under study were determined as 142.92 Bqkg-1, 0.38, 0.47 and 66.47 nGyh-1, respectively. The annual effective dose equivalent (AEDE) varied in the range from 0.03 to 0.12 mSvy-1. It is concluded that the surveyed area do not pose any significant radiological risk to the population and environment.

某深埋输水隧洞放射性环境地质调查与评价

为探究某深埋输水隧洞穿越地层的放射性环境质量,采用原位测试和样品分析等手段,研究隧洞施工期的不利因素。结果表明:隧洞地表沿线的放射性元素含量在背景值变化范围内,未发现放射性异常现象。隧洞穿越的7个钻孔内γ总量和地温测井的结果表明:孔内核素放射性水平较低,基本处于豁免水平,但地温存在异常区域,施工期务必引起重视。钻孔目的层的岩心放射性核素活度浓度低,属于豁免范围内,孔内地下水放射性水平低,满足Ⅲ类地下水要求。辐射防护的计算结果显示,隧洞段地表沿线γ有效剂量当量为0.15 mSv/年,符合国家要求。隧洞段内照射指数和等效镭浓度符合约束值,ZK16钻孔的目的层外照射指数略高于标准值。因此,地下隧洞在施工期需着重关注洞内放射性水平,在辐射异常地段加强岩石采样与分析工作,以保证施工安全。

新型墙材用工业废渣中天然放射性核素分布研究

目的研究在新型墙体材料中大量使用的粉煤灰、煤矸石以及各种炉渣中的天然放射性核素分布特点,为降低公众受照剂量提供科学依据。方法使用高纯锗γ谱仪分析各种工业废渣的核素分布。结果镭当量浓度从高到低依次为粉煤灰(279.13Bqkg-1)、炉渣(225.69Bqkg-1)、煤矸石(141.26Bqkg-1)均不超过OECD规定的限值。226Ra、232Th、40K的活度浓度平均值,粉煤灰分别为127.88,93.83,221.75Bqkg-1;炉渣分别为73.89,97.13,293.44Bqkg-1;煤矸石分别为47.85,45.21,413.56Bqkg-1。同一电厂,不同时间采集的粉煤灰的放射性核素活度浓度会有很大差异,最大值可达到最小值的2倍以上。结论粉煤灰和炉渣在掺入比例上要严格控制在合理的范围,不宜将掺入量超过70%。煤矸石的平均放射性水平与黏土相当,一般在生产过程中掺入比例可以不受限制。新型墙材企业在生产过程中应经常性的检测废渣的放射性水平,使生产的产品中放射性核素达到合理的近可能低的水平。

青岛市区土壤天然放射性核素的外照射水平估算研究

城市的辐射环境质量对于人居和发展规划有重要意义。利用伽玛能谱仪对青岛市区内的天然放射性核素进行了大规模高密度的现场测量,采用Beck公式计算了离地面1m高处的空气吸收剂量率,进而计算了外照射年有效剂量、外照射指数和等效镭浓度,对研究区的外照射水平进行了系统的评价。与和其他国家全国比较,虽然该区的空气吸收剂量率较高,但是其他衡量天然放射性核素外照射水平的指标均在容许范围之内。因此该区属于外照射水平的安全区域,人居环境不受影响。

西安灞桥燃煤电厂周围土壤天然放射性水平

应用低本底多道γ能谱仪测定了燃煤电厂周围土壤中天然放射性核素226Ra、232Th和40K的比活度,评价了其辐射危害。测定结果表明,土壤中226Ra、232Th和40K的比活度分别为27.60～48.78、44.39～61.39和640.19～992.25 Bq/kg,平均值分别为36.07、51.13和733.91 Bq/kg。电厂周围土壤中226Ra比活度大于陕西土壤平均水平,稍小于全国土壤平均值;232Th和40K比活度均大于陕西省土壤和全国土壤平均水平。在距离电厂1 000 m范围内,土壤中226Ra和232Th无明显空间差异,而40K比活度在距电厂100 m处土壤中明显低于400 m和1 000 m处。等效镭活度、空气吸收剂量率和年有效剂量率评价结果表明,燃煤发电对灞桥电厂周围土壤放射性有一定影响,但放射性水平处于正常。

成都市土壤天然放射性核素的外照射水平估算研究

利用IED 22000 A便携式微机多道能谱仪对成都市区土壤的天然放射性核素进行了直接就地测量,估算出天然环境放射性核素^(238)U、^(232)Th、^(40)K的比活度范围分别为10.37～77.19 Bq/kg、17.85～225.74 Bq/kg、284.83～892.67 Bq/kg;外照射指数范围为0.16～0.8;离地面1m高的空气吸收剂量率均值为83.23 nGy/h;γ外照射年有效剂量当量为0.34～0.70 mSv;等效镭浓度的变化范围是59.06～386.45 Bq/kg,均值为164.15Bq/kg。各项指标均在容许范围之内,因而成都市属于外照射水平的安全区域,人居环境不受影响。

Fertility Cancer and Hereditary Risks in Soil Sample of Nasarawa, Nasarawa State, Nigeria

A survey of Fertility Cancer and Hereditary Risks in Soil Sample of Nasarawa was carried out.This study assessed the level of Fertility Cancer and Hereditary Risks from the naturally occurring radionuclides;^(232)Th,^(226)Ra and ^(40)K.12 soil samples collected from the respective part of the Nasarawa were analyzed using the gamma-ray spectrometry NaI(Tl)detector system.The mean concentration for ^(40)K was 645.29±07.32 Bq/kg,for ^(226)Ra was 28.43±4.8422 Bq/Kg and for ^(232)Th was 66.84±2.0201 Bq/Kg.The average effective dose due to the ingestion was 0.36±0.1μSv/y which was approximately 1000 times lower than the world average effective dose.Radium equivalent activity Ra_(eq)(Bq/kg),alpha index and total cancer risk were found to be 161.44±8.08 Bq/kg,0.142±0.02 and(0.21±0.05)×10^(-5) respectively.UNSCEAR/USEPA stipulated that;radium equivalent activity,alpha index,effective dose and total cancer risk should not exceed the limit of 370 Bq/kg,unity,300μSv/y and 1×10^(-4) respectively.Hence the values obtained in this work were within the acceptable limits.This implies that the ingestion or inhalation of soil is not associated with any radiological risk of concern.

北京市花岗石放射性水平调查及核素差异分析

目的通过检测花岗石226Ra、232Th、40K含量,探究可能影响放射性核素差异的因素,根据国家标准以及内外照射指数、镭当量、γ外照射有效剂量当量的计算结果和探究结论为今后在选择花岗石装修或制定防治措施方面提供指导性建议。方法用ORTEC高纯锗(HPGe)γ谱仪测量北京市某石材交易市场采集的放射性样本镭、钍、钾核素含量和226Ra、232Th、40K比活度。结果不同产地、不同颜色的花岗石放射性核素的含量有差别:一般而言南方所产的花岗石放射性核素含量高于北方地区;颜色较深的花岗石核素含量比颜色浅的含量高。基性、超基性的岩石放射性水平比较低;未发生蚀变的岩石放射性水平较低;地质年代越久远放射性水平就越低。此结果仅是我们在选取的19中样品中总结出来的,仅作参考。结论选购花岗石作为装饰材料时尽量选择放射性核素含量低的种类,结合国家安全标准注意其分类和适用范围,注意日常的防护措施,加强通风,加大建材产品监测监督力度,减少辐射对身体的伤害。