扩散型氢计系统在中国实验快堆的实际应用研究

在快堆运行中,钠泄漏是快堆核电厂运行的一大安全隐患,特别是二回路蒸汽发生器换热管破损引起的钠水反应将对反应堆的安全运行造成极大的损害。本文通过对中国实验快堆(CEFR)蒸汽发生器氢计系统在不同工况下的在线监测响应特性的研究分析,掌握氢计的实际运行特性,并对氢计系统在实际应用中存在的问题给出相应的解决措施及建议,优化CEFR氢计系统运行维护技术,对于保证氢计系统可靠运行,及时发现蒸汽发生器换热管的微小泄漏,防止蒸汽发生器中、大泄漏事故的发生,优化工程应用,确保反应堆运行安全,具有重要意义。     

CEFR二回路水锤分析

CEFR以液态钠作为一、二回路冷却剂。二回路蒸汽发生器泄漏发生钠水反应会在二回路系统中引起水锤,水锤事故可以引起管道的甩摆,拉断管道支撑,使管道破裂,甚至直接造成核电厂事故停堆。因此,水锤是CEFR设计和安全分析中的一个重要问题。本工作在清华大学按照CEFR一、二回路系统初步设计参数编制的水锤分析程序的基础上,采用CEFR二回路冷却系统施工设计参数重新进行分析计算。CEFR二回路水锤分析@唐龙 @王彬     

CEFR和BN800系统运行工况的分析和比较

研究反应堆系统的运行工况,对于反应堆的安全运行是非常重要的,本文对我国实验快堆CEFR和俄罗斯BN800快堆的总体特征进行了比较,并对CEFR和BN800的系统运行分类情况进行了比较分析,在此基础上,对CEFR和BN800系统的主要运行工况进行了细致的比较和分析,详细地分析了两个反应堆系统在各种运行工况下运行的要求、工况参数和运行过程以及相应的各项安全要求,比较分析了它们之间的相同之处和区别所在。     

CEFR一回路钠净化系统雾火计算与分析

CEFR一回路钠净化系统是一回路冷却剂边界的一部分,在正常运行时,该系统从反应堆主容器冷池取钠,钠经省热器冷却进入冷阱净化,然后返回省热器加热,最后回到主容器的冷池。本文根据CEFR一回路钠净化系统工艺间内管道和设备的布置,以及通风系统进出口的位置,建立发生事故的工艺间几何模型,确定泄漏点及泄漏流量,使用雾火程序FEUMIX程序进行计算,给出事故房间的气体压力,墙壁混凝土温度,气溶胶浓度的值及相应曲线。计算结果表明,CEFR一回路钠净化系统在发生钠雾火时,事故房间热力学后果在建筑结构可接受的范围内,放射性后果也在可接受…     

中国实验快堆全堆芯流量分配计算与试验

针对中国实验快堆(CEFR)堆芯和一回路的设计特点,开发水力特性计算程序DAEMON,完成不同工况下的全堆芯流量分配计算,给出流量分配不均匀性等参数。在反应堆调试阶段,进行全堆芯流量分配试验。结果表明,程序计算值与试验值符合较好。在此基础上,验证了CEFR堆芯的流体力学设计,并为反应堆调试和运行提供了基础数据。     

中国实验快堆堆芯围桶开孔对正常运行工况影响的分析

堆芯围桶开孔是中国实验快堆(CEFR)事故余热排出系统的重要组成部分之一,是保证该系统形成自然循环排出反应堆事故后剩余发热的关键环节。本文应用通用计算流体力学软件CFX对CEFR堆芯围桶开孔对反应堆正常运行工况的影响进行了模拟,计算了在正常工况运行时,CEFR的反射组件与屏蔽组件热功率对堆芯围桶开孔附近温度场以及流场的影响,给出了堆芯围桶开孔区域的三维温度场、三维流场以及压力分布矢量图。结果表明,目前的设计在满足事故余热排出的要求同时,对反应堆正常运行工况的影响是可以接受的。     

基于Flowmaster的中国实验快堆汽轮机组仿真研究

汽轮机组在中国实验快堆(CEFR)三回路中承担了将热能转换为电能的重要作用,但自安装以来,未在40%P0(P0为满功率)以上工况下运行,故需对其进行必要的仿真模拟。本文根据CEFR中汽轮机组的实际模型,通过Flowmaster仿真平台建立了汽轮机组的仿真模型。利用该模型,得到了满功率运行工况下的稳态结果,该结果验证了设计参数。同时,完成了由满功率到40%P0工况下的瞬态仿真模拟,验证了汽轮机组的部分性能和运行情况。仿真结果表明,利用Flowmaster建立的仿真模型运行情况基本符合设计要求,并为实际运行提供了一定的参考价值。该模型对后续验证快堆三回路其他系统的仿真模型具有一定的参考意义。     

基于Labview的相关法测量钠流量系统设计

为满足中国实验快堆(CEFR)一回路主泵旁路钠流量计校准的需求,设计了1套基于Labview软件的相关钠流量测量系统。本文介绍了相关法的测量原理、设计的相关钠流量测量系统、对该系统的仿真试验和钠回路上的验证试验。试验结果表明,这套基于Labview的相关钠流量测量系统是可行的。本文还进行了该系统的测量误差分析,给出了减小误差的方法。该系统及其试验为CEFR一回路主泵旁路钠流量计在役校准装置的设计、调试和运行提供了依据。     

中国实验快堆蒸汽发生器首次进水试验分析研究

中国实验快堆(CEFR)作为中国第一座钠冷快中子反应堆,蒸汽发生器作为分隔二回路和三回路器的重要设备,其运行的稳定性、可用性对于中国实验快堆的稳定运行具有重要意义。中国实验快堆蒸汽发生器首次进水试验验证了蒸汽发生器具备了在低功率下运行的完整性、可用性、稳定性和良好的传热性能。根据记录数据就钠侧和水侧的对流换热进行了热平衡校核计算,计算结果表明了本次试验钠侧和水侧换热量平衡,计算结果表明在低流量、低钠温的运行工况下水侧为主要换热热阻,该热阻值可以由格尼林斯基(Gnielinski)公式确定。     

池式钠冷快堆二回路钠比活度研究

池式钠冷快堆中的二回路钠比活度影响二回路钠工艺间中的辐射剂量及分区、二次钠泄漏事故的环境影响和运行维修期间工作人员接受的辐射剂量。二回路钠比活度水平是由堆本体屏蔽决定的。本文以中国实验快堆(CEFR)为研究对象,通过研究它们之间的关系,找到设计池式钠冷快堆时确定二回路比活度设计值的方法。研究表明,二回路工艺间中冷阱间的剂量当量率决定了二回路钠比活度值的上限;而从堆容器材料损伤和二次钠事故后果等方面限制推算出的比活度限值远高于上限值,可以据此规律来确定中国示范快堆的二回路比活度设计值,并通过堆本体的屏蔽达到此设计值。     

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.     

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%。     

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.