中子活化瞬发γ射线元素分析技术初探

自六十年代中期以来,中子活化瞬发γ射线元素分析技术(PNAA)在地质勘探、材料成份分析、工业流线监测、以及医学生物学中得到实际应用。与通常的中子活化(NAA)技术相比,它分析的是样品主要成份的百分比含量,由于可利用同位素中子源,这样可在现场进行在线测定。PNAA和NAA一样,都是非破坏性分析,它适宜于大块物质的体分析、生物     

铀芯块样品的核法证分析研究

正核法证学研究能有效应对核安全事件和潜在的核恐怖威胁,防止放射性犯罪或恐怖袭击。通过对核燃料循环不同阶段的核材料分析,揭示核材料的初始来源和整个历程,发现由于不同地质条件与工业过程而遗留在核材料独特的、可区分的特点。在核材料分析过程中,核材料"年龄"、痕量杂质与稳定同位素组成等特征非常重要。本工作以核燃料循环中最重要的产品铀芯块为分析对象,采用核法证分析技术溯源铀芯块的     

从工业γ射线探伤应用中的辐照事故看企业放射源管理

工业γ射线探伤放射源相比其他核技术利用行业用放射源,由于其体积小、重量轻、便于携带等特点,在管理不善情况下,更容易发生事故并产生较大的危害。本文简要总结了我国及其他国家工业γ射线探伤应用中的辐射事故教训,分析事故发生原因,提出工业探伤放射源的管理建议以减少因放射源失控造成的辐射事故的发生。     

从工业γ射线探伤应用中的辐照事故看企业放射源管理

工业γ射线探伤放射源相比其他核技术利用行业用放射源,由于其体积小、重量轻、便于携带等特点,在管理不善情况下,更容易发生事故并产生较大的危害。本文简要总结了我国及其他国家工业γ射线探伤应用中的辐射事故教训,分析事故发生原因,提出工业探伤放射源的管理建议以减少因放射源失控造成的辐射事故的发生。     

美国控制数据公司简介

目前美国控制数据(CDC)公司的Cyber计算机已在全世界核电工业中广泛应用,特别是四大核电设备制造厂(西屋、通用电气公司、燃烧公司及巴布科克和威尔科克斯公司)在反应堆的设计和分析中全都采用cy ber系统。在核电工业中,有许多核应用软件都是     

中子水分仪测量方式的改进研究

中子水分仪在工业现场应用时,有时会因被测量物料中水分不均匀而引起测量误差。本工作利用蒙特卡罗方法模拟了中子水分仪应用中由于物料中水分不均匀所带来的测量误差。为了减小由于水分不均匀带来的测量误差,提出了一种新型的测量方式,即透射加散射测量方式。实验证明,透射加散射测量方式能够有效降低中子水分仪在被测量物料水分分布不均匀情况下的测量误差。该方法用于水分分布复杂条件下的现场测量还需作进一步的分析和研究。     

铀成矿学现实问题

目前,由于对铀矿床形成条件的观点不同。还缺乏一种统一的铀矿床分类方法。苏联学者提出以大地构造学为基础的前寒武纪含铀区域的划分方案。在划分出的每个前寒武纪地壳大地构造单元类型中均产有一定工业类型的矿床(表1)。工业矿床产于活动带和克拉通活     

内生铀矿床成矿物质来源

众所周知,研究地质过程的演化问题是研究地质科学的基础。地质学家非常重视金属矿床在地槽褶皱系、地台和构造岩浆活化区发展史中的位置。由于铀在自然界中非常活跃,以及工业铀矿床产出的地质环境的多样性,因此在这方面铀矿床具有特殊的意义。     

氟和含氟化物的分离和测定方法

一、前言氟及其化合物广泛分布于自然界中,与人类关系极为密切。例如氟化物在原子能工业中起着关键性的作用;在石油、橡胶、塑料等部门中也是重要的组成元素,很有价值;在农药、医药、制铝、冷冻、水处理等工业中也有重要的地位;甚至环境保护、生物生态、人类健康等都有重要作用。因此,其测定方法早为人类所重视。由于氟是极其活泼的元素,与许多元素都有强烈的络合作用,如与常见的元素铁、     

哈萨克斯坦铀工业的困厄及对策

哈萨克斯坦拥有丰富的铀、石油、天然气、煤资源,是世界上最重要的能源矿产地之一。在计划经济向市场经济的转换进程中,哈萨克斯坦铀工业的生存与发展遇到了强劲的挑战和机遇。一方面,由于资金匮乏,铀生产设备与工艺陈旧,铀工业活动导致的环境问题严重,给铀工业的生存带来众多困厄;另一方面,哈境内业已探明的大量低成本、可地浸砂岩铀资源是国家潜在的宝贵财富。多渠道引进外资(向世界银行贷款改造、开发地浸砂岩铀矿山,让外资或由外商与哈合营开发铀矿、积极出口铀、接纳境外核废等)已成为哈萨克斯坦在新世纪初振兴铀工业的希望。     

Preparation of Zn/TiO2 powder and its photocatalytic performance for oxidation of P-nitrophenol

Zn-doped TiO2 catalysts were prepared using a sol-gel method and characterized by XPS,UV-Vis, BET, XRD in this study. Under the irradiation of simulant sunlight, the photocatalytic activity for the degradation of p-nitrophenol was studied too. After irradiation for 2.5 h, the degradation percentage of p-nitrophenol could rise to more than 80 %. The results showed that the spectrum absorption band edge of Zn/TiO2 powder does not broaden obviously comparing with pure TiO2 powder. Zinc exists as Zn （11）. When calcined at 973 K, there is a new phase as ZnTiO3 in Zn/TiO2 catalyst. The order of photocatalytic activity of Zn/TiO2 catalysts calcined at different temperatures for p-nitrophenol is 773 K 〉 673 K 〉 873 K 〉 573 K 〉 973 K and the photocatalytic activity of Zn/TiO2 catalyst calcined at 773 K is better than TiO2 catalysts heated at the same temperature, and outclasses that of commercial TiO2 catalyst. It also showed that the photocatalytic degradation of p-nitrophenol follows first-order kinetics under the irradiation of simulant sunlight.     

Current status of radiation therapy for prostate cancer

Radiotherapy for the treatment of prostate cancer has been extensively explored in the past. Along with the comprehensive understanding of the biology of prostate cancer and rapid advances in terms of technology, the out- come of treatment for the patients with prostate cancer has improved. The authors review radiotherapy as the primary treatment for the disease, with particular emphasis on the technological advances from both the radiobiological and radiophysics aspects. Nonconventional fractionated irradiation like hyper- or hypo-fractionation has been imple- mented in the clinic, the final results still need to be confirmed in the future. Technological advances like IMRT, IGRT, in the last two decades have significantly improved the delivery of external radiotherapy to the prostate. This has re- sulted in an overall increase in the total dose that can be safely delivered to the prostate, which has led to modest im- provements in the biochemical outcome. However, establishing the standard therapy for prostate cancer remains con- troversial. It is hoped that the next decades will bring continued advances in the development of biologicals that will further improve current clinical outcomes.     

水平管内含空气蒸汽强制对流冷凝换热模型研究

为研究含空气蒸汽在水平管内强制对流冷凝换热特性,基于对传热传质过程的分析,建立了管内为环状流与波状流条件下的流动冷凝换热模型。从潜热、显热和液膜3个环节对整个换热过程进行建模,最终得到计算局部冷凝换热系数的理论关系式。模型预测结果与实验数据的对比表明,二者相对偏差在±20%以内,验证了该换热模型的准确性与适用性。通过进一步的研究发现：从换热管入口至出口,随着冷凝的进行,管内换热主要热阻由液膜热阻向气液界面的凝结热阻转变;主流气体对流换热过程基本可忽略。     

Investigations on landmine detection by BF3 detector

Experiments were carried out to investigate the possible use of neutron backscattering for the detection of polyethylene (PE) sample buried in the soil. In detection of landmine by neutrons, the neutron detector and its shield play an important role. In this paper, the effects of graphite, heavy water, polyethylene and boric acid moderators on the flux of back scattered neutrons were investigated. We have also experimentally verified the effect of BF3 detector shield and obtained good agreement with theory.     

Web Services interface of SSRF archive data analysis system

Accelerator database stores various static parameters and real-time data of accelerator. SSRF (Shanghai Synchrotron Radiation Facility) adopts relational database to save the data. We developed a data retrieval system based on XML Web Services for accessing the archive data. It includes a bottom layer interface and an interface applicable for accelerator physics. Client samples exemplifying how to consume the interface are given. The users can browse, retrieve and plot data by the client samples. Also, we give a method to test its stability. The test result and performance are described.     

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.     

Preparation and properties of 117m Sn(IV)-TTHMP in in-vitro and in small animals

In this work,TTHMP was synthesized and labelled with 117m Sn.The preparation conditions,stability and lipophilicity of 117m Sn(IV)-TTHMP were investigated.Biodistribution of the complex in rabbits and mice was studied.It was found that the quantity of TTHMP and pH value of the prepararion solution had vital effects on the labeling yield of 117m Sn(IV)-TTHMP.It was also found that 117m Sn(IV)-TTHMP was hydrophilic and stable at room temperature and 37℃ in open air 117m Sn(IV)-TTHMP showed unexpectedly high bone uptake and bone-to-blood ratio in the animals.This made it potentially useful as an reagent for skeletal scintigraphy and radiotherapy of bone tumors.     

The role of AGFA high-energy CR in the calibration and quality control of multileaf collimators （MLC）

Linear accelerators equipped with multileaf collimators （MLC） are becoming more common and are widely used in the intensity-modulated radiotherapy （IMRT）. There is an imperative need to ensure the commissioning specification of the linear accelerators for the sake of quality assurance （QA） and quality control （QC）. This paper is aimed to investigate the role of AGFA high-energy CR （Computed Radiography） in calibrating dynamic multileaf collimators and evaluating the accuracy of the leaf position. The result shows that AGFA high-energy CR can easily and conveniently be used to calibrate MLC and verify its position. Hence, the application of AGFA high-energy CR is proved to be an accurate and time-saving method for routine MLC QC, especially when MLC calibration adjustments are required.     

微型X射线管空气比释动能和能谱的测量

为研究微型X射线管的特性,通过电离室测量光管出射口30 cm远处的空气比释动能,使用高纯锗探测器分别测量了Ag过滤和Cu过滤下的X射线能谱。结果表明,空气比释动能随电流的增加有线性增加的趋势,能谱图明显的观察到银的两个特征X射线。完成了微型X射线管空气比释动能和能谱的测量方法以及实验测量的工作,为微型x射线管下辐射质的建立提够了条件基础。     

Gamma-ray attenuation technique for measuring void fraction in horizontal gas-liquid two-phase flow

The measurement of void fraction is of importance to the oil industry and chemical industry. In this article, the principle and mathematical method of determining the void fraction of horizontal gas-liquid flow by using a single-energy γ-ray system is described. The γ-ray source is the radioactive isotope of 241Am with γ-ray energy of 59.5 keV. The time-averaged value of the void fraction in a 50.0-mm i.d. transparent horizontal pipeline is measured under various combinations of the liquid flow and gas flow. It is found that increasing the gas flow rate at a fixed liquid flow rate would increase the void fraction. Test data are compared with the predictions of the correlations and a good agreement is found. The result shows that the designed γ-ray system can be used for measuring the void fraction in a horizontal gas-liquid two-phase flow with high accuracy.