Aslam Muhammad, Gul Rahmat, Ara Tauseef, Hussain Manzur
Gamma Spectrometry Laboratory, National Repository, Pakistan Institute of Engineering and Applied Sciences, PO, Nilore, Islamabad, Pakistan.
Radiat Prot Dosimetry. 2012 Sep;151(3):483-8. doi: 10.1093/rpd/ncs018. Epub 2012 Feb 20.
A study on the radiological hazard in Portland cement due to the presence of naturally occurring radioactive materials is being carried out. The Portland cement manufactured in the Islamabad/Rawalpindi region of Pakistan, intermediate products (clinker) and the various raw materials which compose the product have been analysed for (226)Ra, (232)Th and (40)K using a gamma spectrometry system with a N-type high-purity germanium detector of 80 % relative efficiency. From the measured gamma ray spectra, specific activities were determined. The mean values of the total specific activity of (226)Ra, (232)Th and (40)K are 34.2±11.9, 29.1±3.6 and 295.1±66.9 Bq kg(-1), respectively in Portland cement, 28.4±8.7, 11.3±1.7 and 63.1±17.3 Bq kg(-1), respectively in lime stone, 8.2±1.9, 16.2±3.9 and 187.7±53.2 Bq kg(-1), respectively in gypsum, 34.7±13.1, 41.2±6.7 and 187.6±17.2 Bq kg(-1), respectively in clay, 41.1±11.8, 39.3±6.9 and 195.1±29.2 Bq kg(-1), respectively in latrite and 51.1±18.2, 23.2±1.2 and 258.4±15.3 Bq kg(-1), respectively in clinker. The radium equivalent activities (Ra(eq)), external hazard index (H(ex)), internal hazard index (H(in)), absorbed dose rate in air (D) and annual effective dose rate (E(eff)) were also determined. The measured activity concentrations for these radio nuclides and radiological indices were compared with the reported national and international data. All these measured values are comparable with the worldwide data reported in UNSCEAR publications.
一项关于天然存在的放射性物质对波特兰水泥造成的辐射危害的研究正在进行。对在巴基斯坦伊斯兰堡/拉瓦尔品第地区生产的波特兰水泥、中间产品（熟料）以及构成该产品的各种原材料，使用相对效率为80%的N型高纯锗探测器的伽马能谱系统，分析了镭-226、钍-232和钾-40。根据测量的伽马射线能谱，确定了比活度。在波特兰水泥中，镭-226、钍-232和钾-40的总比活度平均值分别为34.2±11.9、29.1±3.6和295.1±66.9贝可勒尔每千克；在石灰石中分别为28.4±8.7、11.3±1.7和63.1±17.3贝可勒尔每千克；在石膏中分别为8.2±1.9、16.2±3.9和187.7±53.2贝可勒尔每千克；在黏土中分别为34.7±13.1、41.2±6.7和187.6±17.2贝可勒尔每千克；在红土中分别为41.1±11.8、39.3±6.9和19年5.1±29.2贝可勒尔每千克；在熟料中分别为51.1±18.2、23.2±1.2和258.4±15.3贝可勒尔每千克。还确定了镭当量活度（Ra(eq)）、外照射危害指数（H(ex)）、内照射危害指数（H(in)）、空气中吸收剂量率（D）和年有效剂量率（E(eff)）。将这些放射性核素测得的活度浓度和辐射指数与已报道的国家和国际数据进行了比较。所有这些测量值与联合国原子辐射效应科学委员会出版物中报道的全球数据具有可比性。
