高灵敏中子剂量当量率仪宽能区响应函数曲线的校准

参考国家相关标准和国际标准化组织(ISO)及国际电工委员会(IEC)对中子剂量当量(率)仪校准的相应标准,对已设计加工组装完毕的一台长圆柱型、较大体积高灵敏中子剂量当量率仪在宽能区(热中子～20MeV)内进行了能量响应和剂量灵敏度的实验校准。能谱响应函数曲线实验校准采用参考仪器和监测仪器归一校准法,利用实验和理论计算方法确定了NH-1型中子剂量当量率仪在较宽能区(热中子～20MeV)内的能量响应曲线;并给出了仪器的综合灵敏度48.9cps/(μSv.h-1)以及在3种特征能谱中的剂量响应。     

改建后的研究性重水反应堆周围中子、γ混合辐射场的测量与评价

本工作对中国原子能科学研究院研究性重水反应堆周围的中子谱进行了测量。对于不同测点处的中子谱,中子平均能量在11—201keV 之间,最大能量低于5MeV;有效品质因数在2.5—5之间;在中子剂量当量总额中,以快中子剂量当量为主。还在反应堆正常运行条件下,测量了人员活动区的中子、γ剂量当量率。在大厅和地下室,中子、γ剂时当量之比的平均值分别为15%和31%,工作人员的年剂量当量有可能大于剂量当量限值。     

双探测器中子剂量当量仪的探头设计

针对单探测器中子剂量当量仪的能量响应性能普遍不好的问题,设计了一种新型中子剂量当量仪,该中子剂量当量仪的探头包含有两个不同厚度慢化体球壳和两个球形3He正比计数管。用MCNP程序对分别嵌入到两个慢化体球壳中心的两个3He正比计数管的能量响应进行了计算。在周围剂量当量的结果计算时,用两个探测器的计数率之比确定1个修正因子以对探测器的计数率转换成中子周围剂量当量率进行修正。经过理论分析和实验验证,该中子剂量当量仪的能量响应性能有一定改善,可使热中子～14MeV范围内的能量响应缩小到0.7～1.3范围内。     

基于3层硅探测器的主动式中子个人剂量计研制

研制了一种具有能量分辨能力的中子个人剂量计。该个人剂量计由3层硅探测器组成，硅探测器周围装有⁶LiF、聚乙烯和含硼聚乙烯作为转化体、慢化体和吸收体。个人剂量计有直读和解谱两种工作模式。直读模式将中子能区划分为低能、中能和快中子3个能区，可实时测量。解谱模式可获得快中子能区的中子能量分布。利用GEANT4程序模拟了7 MeV γ射线的能量沉积谱，设置适当的甄别域以降低γ射线的影响。采用GEANT4程序模拟了个人剂量计对不同能量入射中子的个人剂量当量率响应。在加速器单能中子参考辐射场中完成了单能中子剂量响应的实验校准，对模拟计算的响应函数进行了实验修正，并得出了不同能区的平均中子个人剂量当量率响应。     

高灵敏中子剂量当量率仪的能量和剂量响应校准

参考国内标准化和国际标准化组织（ISO）及国际电工委员会（IEC）对中子（率）仪校准的相应标准,对已设计、加工、组装完毕的1台长圆柱状、较大体积、高灵敏中子剂量当量率仪,在宽能区（热中子～20MeV）内进行了能量响应和剂量灵敏度的实验校准。本文介绍了仪器能谱响应函数曲线实验校准方法、实验方案和结果分析,给出了仪器的综合灵敏度48.9s－1/（µSv•h－1）及在3种特征能谱中的剂量响应。     

西藏地区天然中子能谱测量

本文采用多球中子谱仪和中子周围剂量当量（率）仪分别对西藏地区的天然中子能谱和周围剂量当量率进行了测量,得到了西藏地区不同海拔处的室外天然中子能谱和周围剂量当量率。研究结果表明：该地区室外天然中子的能谱形状基本保持不变,其各能区的中子注量率随海拔的增加而增大,天然中子的总注量率和有效剂量率及周围剂量当量率均随海拔的增加呈指数规律增大;此外,天然中子的有效剂量率可用中子周围剂量当量（率）仪的测量结果乘以能谱 有效剂量转换因子得到。     

中子剂量当量仪的设计

为了提高中子剂量当量测量的准确度,利用MCNP5程序模拟优化了一种球形中子剂量当量仪的能量响应曲线。模拟结果表明,当聚乙烯厚度为10 cm,镉片处于聚乙烯慢化体中0.9–1.0 cm、半径为0.45 cm、长度0.1 cm时,在能量为2.53×10–8–10 MeV,能量响应因子为0.2–1.8,并与相关剂量仪性能进行比较,从而验证了此中子剂量当量仪设计的准确性。     

高灵敏度中子雷姆计数器的研制

本文介绍了两种高灵敏度中子雷姆计数器(NR 1和NR 2)的结构与性能。在热能-17MeV能区,NR 1计数器的剂量探测范围约为10~(-4)—10~2mrem/h,中子剂量灵敏度为140cps/mrem·h~(-1);在热能-7Mev能区,NR2计数器的剂量探测范围约为10~(-4)—65mrem/h,灵敏度为209cps/mrem·h~(-1)。并在现场与2202D型可携式中子雷姆仪(瑞典制)作了比对,在中子近似垂直入射计数器轴线时,±10%内相符。     

高气压组织等效电离室用于混合辐射场测量的实验研究

介绍了基于复合理论的组织等效电离室的设计原理,利用该原理设计的区域中子、γ剂量当量仪可使用1个探头间接测量周围剂量当量、吸收剂量和品质因子。利用加速器和标准辐射场对该装置进行测试,测试结果表明,该装置对于中子和γ辐射场,尤其是对于高能γ、热能至几十MeV的中子具有较好的能量响应和较高的灵敏度,在剂量率高于几十μSv/h时,测量不确定度可控制在±50%以内。该系统可为存在中子、γ辐射场的场所提供必要的测量手段和监控技术。     

BH3105E型中子剂量当量仪研制

研制成功BH3105E型中子剂量当量仪.仪器采用镉吸收棒法实现热中子至14 MeV区间等剂量当量测量;选用6Li玻璃闪烁体作为中子探测器;探头输出信号送至硬件电路进行处理.信号经主放大器、脉冲幅度甄别器、整形器由处理器进行计数采集.仪器系统软件设计实现了测量数据存储,采用串口协议与单片机进行通讯.     

Identification of radiation treatment of wheat （Triticum aestivum. L）and rice （Oryza sativa. L） samples using thermoluminescence of contaminating minerals

Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food. Because of the rapid commercialization of irradiated foods throughout the world, compliance of different regulations relating to use of technology in different countries and demand of consumers for clear labelling of irradiated foods, there is need for the development of analytical methods to detect radiation treatment of food. Among several methods studied so far, thermoluminescence （TL） is an important method that can be used to find out the irradiation history of food that contain even a very minute amount of dust particles. In this study, the irradiated and unirradiated wheat and rice samples were analyzed using the TL method. The samples were purchased from the local market of Peshawar and irradiated to radiation doses of 0.5 and 1.0 kGy using Co-60 gamma irradiator at the Nuclear Institute for Food and Agriculture （NIFA）, Peshawar. The mineral contaminants were isolated by jet water, ultrasonic treatment, and density gradient. TL glow curves of the isolated minerals from irradiated and unirradiated samples were recorded between the temperature ranges of 50-500℃ using a TL reader. Generally, the glow curves for irradiated samples showed much higher TL intensities （TL1） than the unirradiated samples. The results were normalized by rerradiation of mineral samples to gamma-ray dose of 1.0 kGy followed by determination of the second glow curves （TL2）. The ratio of the area of first glow curve to that of second glow curve （TL1/TL2） was calculated for selected temperature intervals and compared with the recommended values for unirradiated and irradiated samples. Finally, the shapes of the glow curves for irradiated and unirradiated samples were also analyzed. On the basis of these results （comparison of TL-intensities, TL1/TL2 ratios and shapes of the glow curves）, all the irradiated and unirradiated samples of wheat and rice were unequivocally identified.     

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。     

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.     

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.     

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.     

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.     

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.