γ辐照装置屏蔽方案评价

依据《γ辐照装置的辐射防护与安全规范》,针对典型γ辐照装置升源状态不同辐射照射途经进行计算分析，以验证屏蔽设计的可靠性；对不同照射途经的辐射剂量率进行比较，提出优化屏蔽计算及设计建议。结果表明：(1)该γ辐照装置屏蔽设计方案满足辐射屏蔽要求；(2)屏蔽计算过程中，屏蔽体外天空反散射剂量率贡献大于直射辐射剂量率，迷道入口散射辐射剂量率贡献大于直射辐射剂量率；(3)考虑γ辐照装置工作负荷较大，并遵循辐射防护最优化原则：在屏蔽设计过程中应考虑一次散射照射剂量率贡献，必要时进行局部加厚处理，对于迷道散射设计次数应在5次以上，楼顶区域不建议布置长期人员居留场所。     

湖南某核技术利用项目辐射防护设计与辐射环境监测验证

为了满足《电离辐射防护与辐射源安全基本标准》(GB 18871—2002)的要求,对湖南某核技术利用项目进行了辐射防护屏蔽设计并在设计的基础上进行了辐射环境监测验证。监测结果表明,该项目辐射防护设计符合相关标准或规范要求。     

贫化铀用于舰艇核动力装置辐射防护的屏蔽性能分析

贫化铀的合理利用和安全处置是国际核工程界长期存在的难题,用作舰艇核动力装置的一次屏蔽结构材料是贫化铀利用的一条途径。文章对贫化铀材料主要是DU混凝土作为辐射防护材料的物理、化学、力学、屏蔽等方面性能进行了调研综述,结合舰艇核动力装置对辐射防护的具体要求,针对舰艇反应堆四层三维屏蔽结构简化模型,利用蒙特卡罗方法模拟计算了贫化铀材料对中子、γ射线的屏蔽性能,通过与铅、钨、铸钢等材料进行对比分析,初步说明了贫化铀或贫化铀混合物用于舰艇核动力装置辐射防护材料的可行性。     

新疆某医院介入诊疗机房辐射屏蔽分析

为了解新疆某医院介入诊疗机房辐射防护水平,判定屏蔽效果是否符合国家标准要求。本文按照设备的运行上限参数和机房相关参数,运用理论估算法,对介入诊疗机房的屏蔽效果进行估算和分析。结果表明:介入诊疗机房四周墙体(地板除外)的设计厚度均大于理论计算厚度,表明机房(地板除外)的屏蔽效果满足国家标准的要求,地板需增加至少0.94衄铅当量厚度才能满足屏蔽要求。     

用于监督样品中子衍射残余应力测量的屏蔽装置

在核工业领域中,有些工程部件在服役过程中会诱发产生一定的放射性,具有放射性的样品在中子残余应力测试过程中首先要考虑辐射安全的问题。基于中子衍射实验技术和辐射安全要求,提出了一种反应堆监督样品中子残余应力测试分析的实验方法和流程。根据该方法和流设计加工了一套实用的屏蔽装置。该装置可以有效屏蔽样品的核辐射,满足一定辐射剂量的安全要求,同时满足中子衍射三维残余应力测量的基本实验要求。     

中子残余应力谱仪静态屏蔽体表面辐射剂量率初算

中子残余应力谱仪静态屏蔽体主要用于对谱仪装置的附加闸门、中子导管等组件的辐射剂量的屏蔽,使装置操作人员可以安全地在装置周围活动。通过MCNP5程序对谱仪装置静态屏蔽体的屏蔽能力进行了计算,可为该方案的改进、优化提供依据,以便最终制造出满足辐射剂量要求的屏蔽体。     

EPR机组堆芯测量系统校验装置的改进

欧洲压水堆(EPR)电厂堆芯测量系统的气动小球测量系统(AMS)校验装置中含有较强的放射源。经评估,该设备屏蔽设计上存在缺陷,增加电厂相关工作人员的工作剂量和意外照射风险。为降低辐照剂量和意外照射风险,采用"迷宫式屏蔽"原理改进了校验装置的屏蔽,并通过蒙特卡洛(MCNP)模拟软件进行效果评估,实现了设计的辐射防护最优化。     

ADS实验大厅中子防护工程技术研究

为了保障加速器驱动次临界系统(ADS)散裂靶与反应堆耦合特性及影响验证实验的顺利进行,以原子能院现有的临界实验装置为基础,对堆厅部分墙体进行屏蔽改造。建造由聚乙烯、镉、铅、钢以及混凝土等材料构成的屏蔽装置,以防止临界装置产生的射线外泄,使工作人员受到的照射保持在合理水平。通过MCNP模拟计算,完成了屏蔽结构的优化设计。基于槽钢支撑结构、铅屏蔽层、镉屏蔽层和聚乙烯屏蔽层等材料组成的组合屏蔽结构建立简化模型,采用ANSYS有限元分析程序计算分析得出各部分应力小于许用应力,稳定性符合要求。最后通过工程实践,完成对屏蔽性能理论计算结果的验证。     

内辐射带质子和电子被动屏蔽

高能量/高通量的质子和电子环境对穿越地球内辐射带的椭圆轨道卫星造成超高剂量的累积辐射效应。代替传统单质铝屏蔽防护措施，提出一种用于屏蔽空间质子和电子的复合材料屏蔽结构。采用多层屏蔽程序(Multi-Layered Shielding Simulation Software,MULASSIS)对穿越内辐射带的卫星轨道质子和电子与4种屏蔽材料(聚乙烯、聚丙烯、钽、铝)相互作用进行仿真计算，比较分析屏蔽后的总剂量、位移剂量随4种屏蔽材料面密度变化规律。结果表明：相同面密度下4种不同材料轨道粒子综合屏蔽效能从大到小分别是：聚丙烯、聚乙烯、铝、钽，其中聚丙烯和聚乙烯对质子和电子的屏蔽效果几乎相同。综合考虑4种材料的质子和电子屏蔽效果及机械性能，设计采用聚乙烯/铝复合屏蔽结构。为保障穿越内辐射带的卫星在轨可靠运行，要求总剂量和位移剂量屏蔽防护目标分别为：50 krad(Si)、2×10¹⁰ p·cm^-2(等效10 MeV质子)。仿真验证结果表明，实现上述卫星抗辐射防护指标条件下，聚乙烯/铝复合结构比单质铝结构节省了至少约27.8%屏蔽质量。     

核电站辐射热点临时屏蔽装置研制现状

在核电站运行和停堆检修期间,使用临时屏蔽装置对辐射热点进行屏蔽是一种常用且有效的辐射防护手段。国内核电站目前使用广泛的辐射热点临时屏蔽装置存在品种单一,功能简单,使用不便等缺点。文章对比总结了国内外辐射热点临时屏蔽装置的应用范围及优缺点,综述了辐射热点临时屏蔽装置的使用情况、发展现状和研究方向,为核电站辐射防护装备的使用和开发提供了参考。     

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.     

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.     

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.