双钩波形板汽水分离器疏水钩优化研究

为提高双钩波形板汽水分离器的分离性能，采用计算流体力学方法建立波形板内的两相流动模型，并对不同结构疏水钩的波形板汽水分离器进行研究。通过数值计算得到了波形板内的速度云图和液滴运动轨迹，并分析了不同进口速度下疏水钩结构对压降和分离效率的影响。结果表明：大部分液滴在前两级通道被分离，进口速度为0.922 m/s时其质量份额可超过50%；疏水钩通过影响流场的局部流速和湍流强度进而影响压降和分离效率，疏水钩对液滴的直接拦截作用有利于提高分离效率。综合考虑分离效率和压力损失获得了综合性能良好的双钩波形板汽水分离器结构型式。     

基于液滴碰撞模型的AP1000波形板汽-水分离器性能及结构优化研究

基于已有的液滴碰撞模型,采用数值模拟方法研究了AP1000波形板汽-水分离器的分离性能,通过优化波形板内部结构得到了具有高效低阻特点的波形板。首先采用液滴碰撞模型对波形板内液滴行为进行数学描述,然后对模型进行了数值求解。随后通过模拟液滴在波形板内的运动和碰撞等行为,得到了波形板对含有不同直径液滴、不同入口液滴体积份额的湿饱和蒸汽来流的分离性能与其内部湿度分布。进而通过对波形板结构的改造设计,达到了提高分离效率、降低流动阻力的目的。本文所采用的数值模拟方法对AP1000波形板汽-水分离器的性能优化有着实际的指导意义。     

旋叶分离器中液滴运动相变特性分析

为研究AP1000核电站蒸汽发生器中初级旋叶分离器的液滴运动相变特性以及液滴相变对汽水分离性能的影响,通过建立液滴运动相变模型,基于AP1000旋叶分离器三维模型,采用欧拉-拉格朗日方法求解气液两相流动模型,计算得到了不同工况下旋叶分离器的汽水分离效率和压降的变化规律,并分析了液滴相变特性对分离效率的影响,获得了不同初始半径液滴的相变特性。计算结果表明:随着蒸汽流速的增加,分离效率和压降快速增加;压降相同时,半径较小的液滴在运动蒸发过程中半径变化百分比较大,相比半径较大的液滴其运动轨迹容易改变,更易逃逸出分离器,造成考虑相变时的分离效率降低;在正常运行工况下,液滴相变对分离效率的影响可忽略。计算结果可为进一步研究汽水分离装置中的汽水分离性能提供理论依据,并用于指导汽水分离装置的设计。     

基于大涡模拟的波形板汽水分离器数值研究

采用Lagrange-Euler方法对波形板汽水分离器内离散气-液两相流动进行了数值模拟研究。对于连续相,使用大涡模拟(LES)湍流模型替代常见的雷诺平均模型(RANS)进行数值模拟。大涡模拟方法将湍流分为大、小两种尺度,大尺度涡采用直接数值求解,只对小尺度湍流脉动建立模型。此方法不仅可给出更准确的分离效率等整体性能,同时可得到流动的瞬态细节和湍流脉动对液滴的影响,进而获得更为准确可信的液滴轨迹。计算结果表明,大涡模拟得到的结果同实验结果符合良好;与雷诺平均模型相比,大涡模拟可为汽水分离器的机理研究和优化设计提供更基础的模型。     

AP1000旋叶式汽-水分离器分离效率与压降的数值模拟

建立基于拉格朗日-欧拉方法的气-液两相流动的数学模型,利用商用计算流体力学软件CFX对该模型求解,数值模拟几何缩比后AP1000旋叶式汽-水分离装置内部冷态工况下气-液两相流动特性。模型中空气为连续相,其内运动的液滴视作离散相,针对液滴在流场中的运动特点,考虑液滴受到曳力、虚拟质量力、浮力和重力,并以此建立空气和液滴动量双向耦合的动力学模型。针对9个不同工况,利用CFX软件对两相流模型进行求解,得到不同直径大小的液滴在流场内的运动轨迹,进而得到分离器的分离效率和进出口总压降。结果显示:分离效率的计算值与冷态实验数据非常吻合,且压降计算值与冷态实验值变化趋势基本一致,验证所建立模型的正确性。     

波形板汽水分离器的实验研究

实验测量了三种不同结构型式波形板汽水分离器的流动阻力、分离效率,观测了水膜流动状态。实验结果表明:各种型式的波纹板汽水分离器都存在一最佳板间距,圆弧形波纹板汽水分离器有良好的性能。     

旋叶汽水分离器试验和数值模拟研究

针对旋叶汽水分离器的缩比模型展开空气-水冷态试验性能分析和数值模拟研究。试验表明：分离效率主要受水流量的影响,随水流量的增大呈逐渐上升的趋势,当水流量增大到0.3 m³/h后增加趋势逐渐减缓进而出现下降的趋势。压降对空气流量变化敏感,随空气流量的增大显著上升。进一步建立旋叶分离器CFD数值分析模型,采用欧拉两流体模型,气相为连续相,液相为离散相,并使用雷诺应力RSM方法求解湍流应力。计算分析了液滴粒径对分离特性的影响,结果表明,液滴粒径分布对分离效率有显著影响,微小粒径液滴的存在显著降低了气液分离效率。     

液滴模型在波形板汽水分离器中的应用

基于液滴运动的物理描述和机理研究,根据液滴在蒸汽流场中的受力及液滴的物性,对液滴的物理状态进行了描述,将单液滴的三维运动模型应用于波形板汽水分离器,对波形板内部蒸汽流场进行了数值模拟,结合单液滴模型程序计算了液滴在波形板内部蒸汽流场中的运动。探讨了液滴在波形板汽水分离器中的分离。     

两级旋风式汽水分离器的分离性能研究

在研究国内外相关资料的基础上,设计了一种两级旋风分离器结构并针对该结构的分离性能进行了详细的数值模拟研究:依据两级旋风式汽水分离器的结构建立计算分析模型,采用数值模拟分析计算了汽水分离器的分离性能,研究不同入口速度、不同湿度对分离器分离特性的影响,搭建了气-水冷态试验回路对模型进行了验证。分析结果表明数值模拟计算结果与冷态试验结果趋势一致,分离效率计算结果偏差小;设计工况中,分离器总体分离效率优于99.5%;一级分离器适用于粗分离,其分离效率随入口湿度和速度的增大而减小;二级分离器适用于小液滴分离,其分离效率与入口速度呈正相关,与入口湿度呈非线性关系。      

蒸汽发生器一级汽水分离器内流场数值模拟

以压水堆核电厂蒸汽发生器一级汽水分离器为研究对象，采用基于计算流体动力学（CFD）的计算软件ANSYS Fluent对湿蒸汽进入汽水分离器后的流场特性和汽水分离性能进行模拟，在模拟过程中采用了欧拉多相流模型和k-ε Realizable湍流模型相结合的计算模型。对工质流经汽水分离器的模拟结果表明，在汽相与液相经由汽水分离器流至各自出口时，出现明显的分层现象。对比不同切向出口和不同液滴粒径下的模拟结果表明，出口面积越大，汽水分离器对液滴的分离效果越好；在0.01~0.10 mm的粒径范围内，液滴粒径越大，分离效果越好。对不同负荷条件下汽水分离器分离效率的模拟结果表明，分离效率随机组负荷升高略有降低。      

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.