共查询到20条相似文献,搜索用时 93 毫秒
1.
整体加热球床通道内流动过冷沸腾起始点的实验研究 总被引:1,自引:0,他引:1
以新概念球床水冷反应堆为背景,对含内热源球床通道中流动过冷沸腾起始(ONB)点的相关特性进行实验研究。选用直径8 mm的表面氧化碳钢球形成随机堆积床,利用电磁感应技术对球床整体加热,研究孔隙质量流速G、工质入口温度Tin和轴向测量位置对ONB点热流密度qONB的影响。实验结果表明,当热流密度q增加到一定值时,壁温Tw随热流密度q的变化曲线会出现拐点,此拐点即为含内热源球床通道内流动ONB点;qONB随G的增加而增大,随Tin的升高而减小;越靠近球床通道出口,qONB越小。导出了计算含内热源球床通道内qONB的无量纲准则关系式,预测值与实验值的偏差在±20%的范围内。 相似文献
2.
3.
石墨粉尘通过高温气冷堆堆芯球床结构的运动行为研究 总被引:1,自引:1,他引:0
高温气冷堆在运行过程中产生带有放射性的石墨粉尘,对反应堆的运行安全和环境安全造成一定影响。本文选取二维球床流场,采用离散相模型分析了堆芯球床结构对石墨粉尘颗粒的扩散和沉积的影响。计算结果表明:球床结构能有效阻碍石墨粉尘颗粒的扩散;沉积在球床结构上的石墨粉尘颗粒数目随堆芯内氦气流速的增加而增大,而由于受到颗粒惯性及热泳力的作用其增长趋势逐渐放缓;石墨粉尘颗粒在球床结构上的沉积效率随粒径的逐渐增加呈现"几乎不变-快速增长-缓速增长"的态势。 相似文献
4.
5.
6.
中国科学院上海应用物理研究所设计的10 MW固态燃料钍基熔盐实验堆(Thorium-based Molten Salt experimental Reactor with Solid Fuel,TMSR-SF)是一种球床型氟盐冷却高温堆,其三维球床随机堆积结构对于堆芯反应性变化和换料分区方案以及热工水力分析中的流动传热都具有重要的影响。为了研究TMSR-SF堆芯球床随机堆积规律,基于PFC3D(Particle Flow Code 3 Dimensional)程序,分别计算并分析了填充颗粒球大小、颗粒间摩擦系数以及填充颗粒球数对球床稳态堆积结构的影响。结果表明:填充直径小的颗粒球,可使球床孔隙率振荡减弱,有利于堆芯功率密度分布的展平;通过减小颗粒间摩擦系数能较好地模拟振动压实效果,压实过程中颗粒间摩擦系数与稳态堆积球床孔隙率和配位数满足负指数关系。当填充颗粒球数超过约8 000个后,球床平均孔隙率和配位数变化趋于恒定,分别稳定在0.43和5.6左右;此时颗粒球数量对球床稳态堆积结构的影响降至最低,可被用来代替满装堆时的球床用于TMSR-SF自然循环的热工水力数值分析,达到节省计算资源的目的。本研究对理解TMSR-SF堆芯球床结构特性与堆积规律具有参考价值。 相似文献
7.
氢-水液相催化交换(LPCE)是处理大量含氚废水的有效途径,而疏水性载体苯乙烯-二乙烯基苯共聚物(SDB)是LPCE的关键材料,对活性组分Pt起到承载作用。采用30mm×400mm玻璃柱模拟催化反应床,研究了SDB疏水性载体与填料的填装方式、气体流速、液体流速、温度以及分层装填高度等工艺条件对床层压力降和持液量的影响。结果表明:当不锈钢θ填料与SDB疏水性载体的体积比为4∶1时,无论采用混合装还是分层装,床层压力降均随气体流速、液体流速和温度的增加而升高,而动持液量随气体流速的增加而减小,随液体流速的增加而增大;混合装的压力降低于分层装,不同分层装对应的床层压力降大小为:四层装三层装一层装两层装。 相似文献
8.
实验研究了不凝性气体(空气)含量、水温和蒸汽质量流速对蒸汽浸没射流冷凝压力振荡特性的影响,实验工况横跨冷凝振荡(CO)区和稳定冷凝(SC)区。结果表明:对于纯蒸汽射流,压力振荡主频随水温的升高而降低,振荡强度随水温的升高而升高;在CO区,振荡主频和振荡强度均随蒸汽质量流速的升高而升高;在SC区,振荡主频随蒸汽质量流速的升高而降低,振荡强度基本上不随蒸汽质量流速的变化而发生改变;对于含空气射流,随空气质量分数的增加,振荡主频总体呈下降趋势,振荡强度先迅速下降后小幅上升,在空气质量分数为0.05~0.1区域内振荡主频和振荡强度均存在极小值。 相似文献
9.
10.
堆芯入口流场设计是小型固态燃料熔盐堆系统项目内容之一,它对反应堆结构的稳定性、堆芯温度和流场分布有着非常重要的影响。研究了熔盐流道流通面积变化对堆芯入口温度、流场分布及压降的影响,优化熔盐流道几何结构。以小型熔盐球床堆模型为研究对象,取符合实际边界条件的输入参数,通过改变熔盐流道流通面积,使用计算流体力学(Computational Fluid Dynamics,CFD)通用程序Fluent 16.0对堆芯入口内熔盐的热工水力特性进行数值模拟。在考虑实际下反射层流道的流通面积占比最大为18.14%下,研究了熔盐流道流通面积占比在区间[0,15.00%]变化。结果表明,堆芯活性区熔盐最高局部热点温度随熔盐流道流通面积比的增大而增高;堆芯入口内的压降随下反射层熔盐流道流通面积比的减小而增大;在径向方向上流进孔道的熔盐流速随着孔道远离堆芯位置而增大。本研究可为小型固态燃料球床熔盐堆优化设计提供一定的参考价值。 相似文献
11.
LIU Xiuhua XU Yunshu ZHONG Zhijing FU Yibei DENG Yi 《核技术(英文版)》2007,18(1):59-64
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. 相似文献
12.
FU Shen SUNYi LU Yaohong 《核技术(英文版)》2007,18(2):65-72
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. 相似文献
13.
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. 相似文献
14.
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。 相似文献
15.
D.Rezaei OCHBELAGH H.Miri HAKIMABAD R.Izadi NAJAFABADI 《核技术(英文版)》2007,18(4):237-241
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. 相似文献
16.
LI Lin SHEN Liren ZHU Qing WAN Tianmin 《核技术(英文版)》2007,18(4):193-197
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. 相似文献
17.
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. 相似文献
18.
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. 相似文献
19.
WENG Jianqing HE Jun XIANG Yuanyi WANG Kan LI Xia HAN Zhengdong 《核技术(英文版)》2007,18(6):366-371
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. 相似文献
20.
LI Zhaobin XIONG Fei HUANG Guofeng CAO Zheng JIANG Ruiyao FU Shen 《核技术(英文版)》2007,18(3):145-149
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. 相似文献