DQ-2型气载放射性碘采样器的研制

本文主要介绍了DQ 2型气载放射性碘采样器的结构特点和技术性能的测试结果。粒子碘单元采用直径 60mm的高效过滤膜 ,气态碘单元采用 2级以粒径 60～ 80目、厚度为 2cm的浸渍椰壳活性炭为吸附剂的活性炭盒采样。测试结果表明 :1 )气密性好 ,气态碘单元未见可检出的泄漏 ,粒子碘单元的泄漏率小于 0 .1 % ;2 )阻力较小 ,在 8.0m3/h的流量下 ,采样器的总阻力为 3 0kPa;3 )效率高 ,对粒子碘的采样效率可达 99.9% ,甲基碘的吸附效率随采样流量和相对湿度的增加而下降 ,当流量为 3 .0m3/h,相对湿度低于 40 % ,炭层厚度为 2cm时 ,对甲基碘的吸附效率达到 99.997% ,可用于碘吸附器的除碘效率试验 ;4)采样器在 80℃下仍可使用 ;在高相对湿度 (95 % )时 ,推荐的采样流量为不超过 3m3/h。     

DQ—2型气载放射性碘采样的研制

本文主要介绍了DQ－2型气载放射性碘采样器的结构特点和技术性能的测试结果。粒子碘单元采用直径60mm的高效过滤膜，气态碘单元采用2级以粒径60－80目，厚度为2cm的浸渍椰 壳活性炭为吸附剂的活性炭盒采样。结果表明：1）气密性好，气态碘单元未见可检出的泄漏，粒子碘单元的泄漏率小于0．1％；2）阻力较小，在8.0m^3/h的流量下，采样器的总阻力为30kPa;3）效率高，对粒子碘的采样效率可达99．9％，甲基碘的吸附效率随采样流量和相对湿度的增加而下降，当流量为3.0m^3/h，相对湿度低于40％，炭层厚度为2cm时，对甲基碘的吸附效率达到99．997％，可用于碘吸附器的除碘效率试验；4）采样器在80℃下仍可使用；在高相对湿度（95％）时，推荐的采样流量为不超过3m^3/h。     

α粒子微束定点照射--细胞的放射生物学效应及精确性分析

进行微束试验的关键是能够精确地控制照射的粒子数和将粒子准确地射入受照射位点.该研究通过对哥伦比亚大学单粒子微束装置在精确性、准确性以及各项指标的分析发现该装置可精确地控制照射粒子数,精确率为98.4%.同时,它可将α粒子准确地射入受照射位点,束半径为34,达到设计4的标准.在对细胞特定位点如细胞质照射上,粒子击中细胞质至少一个位点的概率为90%,在这一过程中的偶然核击中率,对大多数照射剂量(8个粒子)均小于0.8%.应用该微束装置的放射生物学研究发现单个α粒子仅导致大约20%的致死率,其存活率曲线类似于用常规照射获得的平均粒子存活曲线.诱变试验首次证实单个α粒子在AL细胞的CD59基因位点可诱导出比对照高出3倍数量的诱变子,诱变率随粒子数的增加而增加.这一结果不同于常规照射中,诱变率在高剂量照射后下降的结论.     

反应堆安全壳的局部泄漏率试验

本文扼要介绍了安全壳密封(泄漏)试验中局部泄漏率试验的类型和项目、典型试验方法、使用仪表的选择要求以及允许泄漏率和试验周期等     

基于β-γ符合法测量的在线啜吸检测装置的研制

反应堆运行期间燃料包壳时常会发生破损，当燃料组件发生破损后，核电厂通常会在换料过程中使用在线啜吸装置对每个燃料组件进行啜吸试验，通过裂变产物分析确定被测组件是否发生破损，然而受核岛内过强的辐射环境干扰影响，传统单一β或单γ粒子检测设备的检测结果时有误判或漏判发生。本文设计了一种基于β-γ符合法测量技术的在线啜吸检测装置，装置含有β和γ粒子探测器，并构建了β-γ符合检测通道，融合了现有β、γ破损判断技术，同时增加了基于β-γ符合判断的结果。相关应用结果表明：在核岛内较强辐射干扰下，本系统符合测量本底计数率可达到0.04 s^-1，装置对¹³³Xe最小可探测活度(MDA)达23.7 Bq，检测灵敏度优于单一β粒子或γ粒子检测模式；3种判断模式的应用大幅提升了破损判断结果的可靠性。该装置可以替代现有单一粒子检测模式的在线啜吸检测装置应用于核电厂开展相关检测工作。     

Cx F-2气溶胶两级个人采样器

该仪器由采样头和驱动装置(主机)组成(外配有自动充电器)。采样头可把被采样的粒子分为“可吸入”与“不可吸入”的两个部分而分别收集起来。仪器体积小重量轻,可佩带在接触有害气溶胶人员的身上,采集呼吸带的粉尘粒子,为吸入危害评价提供可靠数据。采样器流量稳定使用方便,适用于工作场所粉尘的个体采样和常规采样。仪器也可配接各种采气头,用于工作场所和环境中有毒气体的采样,做到一机多用。     

大亚湾核电厂反应堆一回路开口后泄漏率试验优化

大亚湾核电厂《安全相关系统和设备定期试验监督要求》中规定,在打开了反应堆冷却剂系统的任何操作之后,都需要将一回路压力提升到绝对压力15.8 MPa,执行一回路泄漏率试验。试验超出运行技术规范对第二道屏障15.5±0.1 MPa的参数要求限制,存在安全风险。通过对反应堆一回路开口后泄漏率试验的研究,分析了核电厂一回路开口后泄漏率试验的设计目的、稳压器安全阀换型对试验内容的影响。综合考虑大亚湾核电厂系统及设备的实际情况,经过试验风险分析及优化试验先决条件的参数,制定了该试验的优化方案。结果表明,大亚湾核电厂反应堆一回路开口后泄漏率试验压力由15.8 MPa调整为15.5 MPa,可以在满足核安全要求的前提下降低试验的安全风险,减少超正常运行范围时限。     

环己烷法用于碘吸附器泄漏率检测技术研究

环己烷法是人员可居留空间碘吸附器有效性评价试验方法之一。通过泄漏率模拟试验、环己烷法与氟利昂法对比试验、重复性试验、现场应用对比试验等研究结果表明:环己烷试验方法能够有效测量通风系统中碘吸附器微小泄漏,是一种灵敏度高且重复性好的检测方法;采用环己烷法泄漏率测量结果与氟利昂法和放射性甲基碘法结果一致,各项性能指标均满足碘吸附器泄漏率检测要求,可替代氟利昂法和放射性甲基碘法用于碘吸附器泄漏率检测试验。     

核电厂蒸汽发生器一次侧向二次侧泄漏率取值研究北大核心CSCD

合理确定蒸汽发生器一次侧向二次侧泄漏率取值,并据此制定核电厂运行策略,对核电厂的安全及稳定运行意义重大。本文根据泄漏率数值使用目的,将泄漏率分为用于辐射防护设计的泄漏率取值、用于核电厂运行控制的泄漏率控制值、用于保证蒸汽发生器传热管完整性的泄漏率保护阈值三大类,并探讨了各类取值的确定依据。完成了对国内外核电厂蒸汽发生器一次侧向二次侧泄漏率取值情况的调研分析,结合研究情况,提出了我国核电厂蒸汽发生器一次侧向二次侧泄漏率取值及控制的建议。     

虹吸破坏装置设计验证试验研究

<正>为了对示范快堆虹吸破坏装置进行设计验证,建造了一套可用于该装置功能验证的试验系统以完成相关试验研究。示范快堆的虹吸破坏装置是用于一回路净化装置堆外管路发生破口时,终止或延缓由虹吸现象引起的液钠泄漏事故的专用安全设施。针对该装置的运行特点验证试验系统模拟了虹吸破坏装置的设计结构、堆内相对位置、堆外管路流动特性,并在试验中模拟堆内稳态     

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.