承压热冲击下压水堆压力容器壁面换热特性的数值模拟研究

为了研究压水堆因安注冷水直接注入反应堆压力容器下降环腔而导致的承压热冲击（PTS）热工水力问题，基于1∶10比例模型，应用计算流体力学商用软件FLUENT5．4进行了紊流流动换热的数值模拟分析，同时进行了常压传热实验研究。针对下降环腔折算流速0．5m/s，安注流速10m/s的典型工况，研究了压力容器下降环腔的壁面换热特性。通过分析下降环腔内的流动及混合特性，从流动机理上解释了压力容器内壁上准重接触点附近换热强烈的现象，并指出壁面换热强弱与近壁流体紊流脉动动能密切相关，为热冲击分析提供参考。     

PTS瞬态流动与换热数值模拟研究

为了研究压水堆因“直接安注”冷水注入压力容器下降环腔而导致的承压热冲击（PTS）热工水力问题,基于1:10比例模型,应用计算流体力学软件FLUENT5.4进行了紊流流动换热的数值模拟分析,同时进行了常压瞬态传热实验研究。针对下降环腔折算流速0.5 m/s,安注流速10m/s的典型工况,研究了安注水开启后下降环腔内的瞬态流动换热特性,数值模拟与实验结果吻合良好。考察了压力容器安注接管出口区环形焊缝区及堆芯段筒体中子强辐照区所承受的热冲击状况,基于稳态流动研究了下降环腔内流体混合特性及流动机理,为热冲击分析提供参考。     

反应堆压力容器直接安注热分布特性研究

我国非能动系列压水堆将应急冷却系统冷却水的注入管道直接连接于压力容器上,与传统的冷管段安注不同,这种安注方式被称之为反应堆压力容器直接安注。本文以安注条件下的反应堆压力容器为研究对象,采用物理实验与数值分析结合的方法,对安注流体在压力容器表面形成的热分布形态进行研究。研究发现,不同于传统的主管道冷段斜接管安注方式,直接安注条件下安注流体在下降环腔中的分布形态接近于等腰三角形。以实验结果为基础,结合数值计算验证,发现了压力容器热分布角与流速比成正比关系,并进一步提出了安注流体分布计算模型,从而为反应堆安全设计提供参考。      

带热套管的T型接管内流动换热的数值模拟和实验研究

为了分析核反应堆冷却剂系统中带热套管T型接管内由于注入非等横向射流导致的构件热冲击状况，本文应用计算流体力学商用软件FLUENT5．3进行了紊流流动换热的数值模拟，分析了主管及接管与热套间环腔内的流动换热特性，针对套管上开有通流小孔，并采用凸台支撑的热套管结构形式，模拟了射流与主流流速比为0．05及0．5两种典型工程，传热实验，研究了主管及接管内壁近壁区域的传热特性，并讨论了热套管尺寸变化对接管热冲击的影响，结果表明，数值模拟与实验数据吻合良好，热套管对构件的热保护程度与热套管结构形式及流速比密切相关，适当减小流速比有利于改善构件热应力状况。     

反应堆压力容器下降环腔在有安全注入流动时的瞬态温度变化

在1／10的比例模型上完成了反应堆压力容器下降环腔在有安全注入流动时的瞬态温度变化。实验考察了有一回路流动和无一回路流动对瞬态温度变化的影响。实验证明：无一回路流动时，下降环腔内瞬态温度的变化速度和幅值随安全注入充速的增加而增加；有一回路流动时，下降环腔内瞬态温度的变化幅值比同安全注入流速时无一回路流动的变化幅值要小。     

承压热冲击下反应堆压力容器中流体的瞬态混合特性

热冲击下,反应堆压力容器中的热工水力特性是一个与反应堆安全密切相关的课题。本文在1/10的模型体上进行了高温高压下安全注水时流体的瞬态混合特性实验,得到了在有回路流动和无回路流动时以及不同的环腔流体温度下的混合特征。结果表明,环腔无流动时,随着安全注水流速的提高,混合函数下降得更快,幅度更大;环路有流动时,混合函数变化缓慢：当环腔内的流体温度达到一定的数值后,压力容器部分区域的混合函数发生明显变化。     

承压热冲击下AP1000压力容器直接安注瞬态数值模拟研究

基于计算流体动力学(CFD)分析方法,采用流固共轭传热方式,对非能动堆芯冷却系统(PXS)的堆芯补水箱(CMT)热态功能试验、CMT注入同时自动减压系统(ADS)动作、蓄压安注箱(ACC)安注后CMT再注入以及常规余热排出系统运行等4种工况下反应堆压力容器(RPV)环腔内流动传热状态进行瞬态数值模拟,研究RPV壁面温度瞬态变化以及环腔下降段内流体的混合特性。结果表明:4种工况下直接安注(DVI)接管管嘴与RPV内壁面相交斜面处冷却水混合剧烈,冷段是否有流体注入环腔对其内流体温度分布变化影响巨大,且DVI接管管嘴局部区域将发生较大的温度变化。     

反应堆直接安注结构热工影响分析

建立了反应堆压力容器直接安注的实验模型,进行传热和流动实验。实验对比研究了文丘里管和直管两种不同安注管结构下压力容器不同区域的流动混合、传热系数以及相应的温度变化,并通过可视化实验对比验证了不同安注模型的流场,对不同结构下安注管的阻力特性进行了分析。研究结果表明,不同安注管在流动阻力上存在较大差异。研究结果为反应堆压力容器安注管的设计选择提供了重要依据。     

反应堆压力容器下降段水-蒸汽CCFL实验与模型研究

为探究反应堆压力容器下降段在喷放末期冷段安注过程中的水-蒸汽逆流特性,建立下降段逆向流动限制(CCFL)模型,开展了基于压力容器模化本体的下降段CCFL实验研究以及建模分析。通过实验研究获得了不同入口安注水流量、安注水过冷度、堆芯蒸汽流量等条件下的下降段环腔内的安注特性数据,并基于实验数据进行了CCFL建模分析。结果表明,开始发生CCFL的蒸汽无量纲流速与入口安注水无量纲流速呈现正相关,基于无量纲流速建立的模型斜率与入口安注水无量纲流速呈现高度指数关联。本文建立了适用于从不发生CCFL至不完全CCFL,再到完全CCFL的下降段水-蒸汽气液逆流全过程预测模型。     

不同倾角射流时近壁区流动与传热特性研究

针对反应堆冷却剂系统中不同倾角三通构件射流时近壁区流动与传热特性,在试验研究的基础上,比较分析了流速比在0～2范围内,射流以45°、90°倾角入射主流时三通构件不同区域的流动特性、近壁区混合函数及无量纲换热系数。结果表明,不同入射角对混合函数及无量纲换热系数的变化趋势影响不大,控制变化趋势的关键参数依然是流速比,入射角仅对混合函数及无量纲换热系数的幅值大小有一定影响。     

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.     

有效探测面积大于1000 cm2的正比计数器测量系统性能测试

为对自制的活性面积高达1 000 cm²的大面积源进行表面发射率定值,同时作为现有2πα、2πβ表面发射率标准装置能力的扩充,研制了一套内置式大面积2π多丝正比计数器测量系统,并利用活性区直径为8 mm的²⁴¹Am点源及活性区面积为10 cm×15 cm的大面积²⁴¹Am和⁹⁰Sr-⁹⁰Y源对其进行计量学性能测试。结果表明：计数器内计数响应均匀性优于±0.4%,有效探测面积达1 400 cm²;所得²⁴¹Am源高压坪曲线的坪长为1 400 V,坪斜为0.27%/100 V,坪区内计数变化为0.87%;⁹⁰Sr-⁹⁰Y源高压坪曲线的坪长为300 V,坪斜为0.75%/100 V,坪区内计数变化为0.80%;10次测量重复性好于0.4%,8 h内短期稳定性好于0.3%,1 a内长期稳定性好于0.8%。     

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.     

Interaction between uranium and humic acid (Ⅰ): Adsorption behaviors of U(Ⅵ) in soil humic acids

The adsorption behaviors of uranium on three soil humic acids (HAs), which were extracted from soils of different depths at the same site, were investigated under various experimental conditions. The adsorption results showed that U(Ⅵ) in solutions can be adsorbed by the three soil HAs, with the order of FHA (HA from 5 m depth of soil) ＞SHA (HA from the surface) ＞THA (HA from 10 m depth of soil) for adsorption efficiency in each desirable condition, and the adsorption reached equilibrium in about 240 min. Although the maximum adsorption efficiency was adsorption could be described with Langmiur isotherm or Freundlich isotherm equation. The L/S (liquid/solid, mL/g)ratio and pH were important factors influencing the adsorption in our adsorption system besides uranium concentration. The adsorption efficiency decreased with the increase of the L/S ratio and pH at the pH range of 2.0-3.0 for SHA and THA or 2.5 - 6.0 for FHA. However, no significant difference in adsorption of U(Ⅵ) was observed at the experimental temperature. All the results implied that humic substances have different characteristics in samples even collected at the same site.     

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。     

The preclinical pharmacological study of dopamine transporter imaging agent 18F-FP-β-CIT

The paper is to study pharmacologic characteristics of 18F-FP-β-CIT (18F-N-(3-fluoropropyl)-2β- carbomethoxy-3β- (4-iodophenyl)nortropane) as an imaging agent for dopamine transporter. The radiochemical purity of 18F-FP-β-CIT in aqueous solution was over 95% after standing at room temperature for 4h. Biodistribution displayed rapid uptake in rat brain (1.375 %ID/organ at 5min and 0.100 %ID/organ at 180 min) and the striatal uptake was 1.444,0.731, 0.397, 0.230 and 0.146 %ID/g at 5, 30, 60, 120 and 180 min, respectively. The values of striatum/cerebellum,striatum/frontal cortex and striatum / hippocampus in rat's brain at 30 min were 3.38, 2.17 and 2.40 respectively. The uptake in striatum can be blocked by β-CFT, suggesting that 18F-FP-β-CIT binds to DAT peculiarly. The compound was rapidly cleared from monkey's blood. The striatal uptake was bilaterally decreased in the left-sided lesioned PD rats, compared with normal control. Brain PET imaging studies in normal monkey showed that 18F-FP-β-CIT was concentrated in striatum. The test of undue toxicity showed that the dose received by mice was 1250 times as by human, which indicates that 18F-FP-β-CIT is very safe. So 18F-FP-β-CIT is a promising PET imaging agent for DAT with safety and validity.     

Information for authors

<正>1.NUCLEAR SCIENCE AND TECHNIQUES(NST),a bimonthly journal,is devoted to all aspects of nuclear science and technology,theoretical or experimental.Its special interest lies in the subjects of synchrotron radiation science and technology;low energy accelerators,radiation technology and applications;radiochemistry,radiopharmaceuticals and nuclear medicine;nuclear electronics and instrumen-     

PLASMA SCIENCE AND TECHNOLOGY AUTHOR INDEX TO VOLUME 16(2014)

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