爆破后压入式通风独头巷道内氡的运移模型

为有效指导铀矿井下独头巷道的通风设计,基于质量守恒定律和置换通风理论,首先建立了描述爆破后压入式通风独头巷道内抛掷空间和风流末端氡活度浓度随通风时间变化的计算模型,利用该模型得到了达到氡活度浓度限值条件的最短排氡通风时间的确定方法;然后分析了不同参数对风流末端氡活度浓度以及最短排氡通风时间的影响。结果表明,爆破后,独头巷道风流末端氡活度浓度在一定通风时间内保持不变,之后瞬间增至峰值,最终逐渐衰减至稳定;在其他参数一定的情况下,风流末端氡活度浓度开始剧增的时间随巷道长度的增加而减小,随风量增加而增大;风流末端氡活度浓度衰减速率随风量的增加而增大;风流末端氡活度浓度峰值随掘进面铀品位的增加而增大;最短排氡通风时间随巷道长度和掘进面铀品位的增加而增大,随通风量的增加而减小。     

压抽混合式通风独头巷道内氡及氡子体浓度的计算模型及其分布规律研究

压抽混合式通风是长距离独头掘进巷道内控制氡及氡子体浓度重要的通风方式,研究该种通风方式下巷道风流中氡及氡子体浓度分布规律对指导其通风和辐射防护设计具有重要的意义。为此,根据氡与氡子体之间的衰变关系,建立了风流中氡子体α潜能浓度与氡活度浓度之间的简化数学计算模型;接着,分析了独头巷道受限空间内氡及氡子体的来源,并基于巷道风流的紊流传质理论,建立了压抽混合式通风方式下风流中氡活度浓度与氡子体α潜能浓度分布的数学计算模型;最后,针对一个具体的独头巷道,探讨了通风量和岩壁氡析出率对整个巷道内氡浓度和氡子体α潜能浓度分布的影响,同时提出了独头巷道内降低氡及氡子体致工作人员剂量的防护措施。     

抽出式通风独头巷道内氡及氡子体浓度的分布及特性分析

铀矿井下的独头巷道是氡及其子体浓度分布很高的场所。为指导抽出式通风独头巷道的排氡和排氡子体通风设计,初步完善了独头巷道通风气流中氡浓度与氡子体α潜能浓度之间的简化数学关系,分析了通风阻力对独头巷道岩壁氡析出率的影响;分别得出了抽出式通风独头巷道风流中氡浓度与氡子体浓度分布的数学计算模型,利用该模型分别得到了排氡和排氡子体最小风量的计算公式;针对具体的独头巷道,研究了巷道内氡浓度及氡子体浓度的分布规律以及排氡和排氡子体最小风量的变化规律。研究结果表明,距离抽出式通风独头巷道入口越远,巷道内氡浓度及氡子体浓度越高,氡及氡子体的浓度均随通风量的增大而减小,随岩壁氡析出率而增大;排氡和排氡子体所需的最小风量均随岩壁氡析出率而增大,随巷道长度而增大。     

2021年丹东市办公场所室内氡浓度及其影响因素分析

为明确丹东市办公场所室内氡活度浓度水平及其影响因素,并估算室内氡对公众所致年有效剂量是否对人体有潜在危害。选择丹东市42处办公场所,使用RAD7测氡仪对其不同楼层室内氡活度浓度进行测量,并计算室内氡及其子体年有效剂量。结果表明,丹东市内办公场所氡活度浓度的范围为4.17-113.29 Bq/m³,平均值为32.99 Bq/m³,符合GB/T 16146—2015《室内氡及其子体控制要求》,室内氡导致的年有效剂量为0.46 mSv。丹东市办公场所室内氡活度浓度处于安全范围。室内氡活度浓度随房屋建造年代的增加基本呈降低趋势;室内氡活度浓度随楼层的增高呈下降趋势;铺装地面的室内氡活度浓度低于未铺装地面的室内氡活度浓度;通风条件好可以显著降低室内氡活度浓度。     

土壤氡测量在呼斯梁—柴登壕地区砂岩型铀矿勘查中的应用

通过呼斯梁―柴登壕地区土壤氡活度浓度测量数据的处理,划分出土壤氡活度浓度异常范围,圈定了测区内重点成矿预测区土壤氡活度浓度异常分布范围:盐路渠和巴定壕附近。证明区域土壤氡活度浓度测量可实现盆地砂岩型铀矿快速评价的目的。     

ISO 11665-5:2020 环境中放射性活度测量-空气:氡-222 第5部分:放射性活度浓度的连续测量方法

正该文件描述了连续测量氡-222的方法。显示了连续测量开放或封闭大气环境中氡活度浓度的时间变化。该文件旨在评估环境、公共建筑、家庭和工作场所中氡活动浓度的时间变化,作为通风和/或气象条件等影响量的函数。该测量方法适用于氡活度浓度大于5 Bq/m~3的空气样品。     

长沙市地铁一号线车站内氡活度浓度的调查与评价

为了调查长沙市地铁一号线车站内氡活度浓度水平,采样典型抽样法,随机抽取5个车站对其中的氡活度浓度进行测量及评价。借助于径迹蚀刻片,用累积法对车站内的车控室、站台、客服中心的氡活度浓度进行调查。结果表明,长沙市地铁1号线车站内氡活度浓度的范围为22.5～53.0 Bq/m³,均值为35.3 Bq/m³,与长沙市室内氡活度浓度平均值(37.4 Bq/m³)的偏差仅为5.6%,远低于国家现行标准《公共地下建筑及地热水应用中氡的放射防护要求》(WS/T 668—2019)的限制要求;车站内氡活度浓度所致工作人员及公众的年均有效剂量分别为0.28 mSv和0.08 mSv,地铁内的氡气所致工作人员及公众年均有效剂量处在本底水平范围内,满足《电离辐射防护与辐射源安全基本标准》(GB 18871—2002)的限制要求。     

青岛市区土壤中氡的测量与分析

用0.2 km×0.2 km的网格布点,采用FD-3017型RaA测氡仪测量了青岛地区岩石、土壤共2 401个样点中的氡活度浓度,对本区土壤氡的分布规律进行了分析.结果表明,青岛土壤氡活度浓度点位平均值为4 483 50 Bq/m3,属于土壤氡活度浓度正常地区;本区地下土层中土壤氡活度浓度与岩性酸性强弱有一定的关系,一般情况岩性酸性偏强地区的土壤氡活度浓度也偏高;另外在构造的断裂地带有多处氡活度浓度偏高点出现,这进一步证实了土壤氡的析出与地质岩性和构造裂隙之间存在一定关系.     

成都市某办公场所室内氡活度浓度水平调查及污染研究

采用固体径迹蚀刻法和瞬时法对成都某办公场所室内氡活度浓度展开调查研究。结果表明:该办公场所室内累积氡活度浓度的范围为10.82～102.50 Bq/m³,算术平均值为(36.56±17.38) Bq/m³,低于全国和世界平均水平。调查研究证实了玻璃墙体和橡胶地面等新型装修材料可有效减少室内氡,验证了通风是降低室内氡活度浓度的有效措施。研究发现,环境空气质量中高浓度的PM_2.5和PM₁₀对办公场所室内和户外氡活度浓度水平均会产生影响。通过发现污染并处理低本底实验室内的氡活度浓度异常给出建议:避免放射性核素浓度较高的样品暂存于测试设备附近;为降低氡及子体对测试的干扰,提高分析结果的准确度,建议升级改造低本底实验室的新风系统。     

土壤氡测量在温家梁地区砂岩型铀矿勘查中的应用

通过处理温家梁地区土壤氡放射性活度浓度测量数据,划分出土壤氡放射性活度浓度异常范围,在测区内重点成矿预测区圈定了2条EW向土壤氡放射性活度浓度异常带:边家渠—徐家梁—先锋3队—温家湾—皮匠壕和农胜4队—色连3队异常带。证明区域土壤氡放射性活度浓度测量可实现快速评价北方中新生代盆地寻找砂岩型铀矿的目的。     

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.     

The control system for SSRF injection and extraction

This paper introduces the injection and extraction control system design for SSRF,which is a distributed control system aimed at stability and reliability of the pulse power supplies,PPS(Personnel Protection System)and MPS(Machine Protection System).The hardware environment is mainly based on PLC(Programmable Logic Con- troller),and ARM(Advanced RISC Machine)is also applied for studying stability of the power supplies.WinCC and EPICS(Experimental Physics and Industrial Control System)have been selected as the platforms of SCADA(Super- visory Control and Data Acquisition).For unifying the interfacing to the control computer,all front-end equipments are connected via Industrial Ethemet.     

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.     

Gamma radiation levels in the ambient environment of the QNPP Base

Monitoring results of gamma dose rate level in 1992～2004 in the ambient environment of the Qinshan Nuclear Power Plants(QNPP)Base,the northeast of Zhejiang Province,are reported in this paper.It is shown that the gamma dose rate of five monitoring sites of 2.5 km to QNPP Base is 84～113 nGy/h,with an average of 96 nGy/h in the 13 years.The average value is close to the background level of 93 nGy/h prior to operation of the QNPP Base,and is lower than the monitoring result of 101 nGy/h at the reference site in Hangzhou City.Within 50 km from the QNPP Base,the cumulative dose rate of the thermoluminescent dosimeter(TLD)is 90 nGy/h,which is lower than the back- ground level of 111 nGy/h.