基于概率因果模型与遗传算法的船舶核动力装置故障诊断的新方法

介绍一种将概率因果模型和遗传算法相结合的核动力装置二回路凝给水系统的故障诊断方法,它将概率因果模型的似然函数作为遗传算法的适应函数,从而将复杂系统的故障诊断转化为最优问题。仿真结果表明,该方法能够适应诊断过程中出现的不确定性,并实现多故障诊断,具有较高的诊断可靠性和实用性。     

BP－RBF神经网络在核电厂故障诊断中的应用

本工作将BP（backpropagation）神经网络与RBF（radialbasisfunction）神经网络相混合,并将其应用于核电厂的状态监测与故障诊断系统中,通过对核电厂典型故障的特征分析,建立相应的网络结构。为验证该混合网络的有效性,在核动力装置模拟器上进行了仿真实验研究,并用VisualBasic6.0编写了网络程序。研究结果表明：该混合网络具有良好的诊断准确性、实时性和可扩充性。     

压水堆核电厂二回路ETA水化学处理研究

秦山核电厂320 MW核电机组使用乙醇胺(ETA)替换氨作为二回路系统p H调节剂后,在给水p H相同的条件下,汽-水分离再热器(MSR)疏水、蒸汽发生器(SG)排污水的p H明显升高;汽-水两相中水相区域设备的腐蚀产物铁含量明显降低,流动加速腐蚀得到抑制,有效改善二回路系统的腐蚀状况;腐蚀产物向蒸汽发生器二次侧的转移得以降低;同时进一步提高凝水混床的周期制水量,减少了凝水混床树脂的再生次数及再生酸、碱的用量和耗水量,从而减轻运行人员的工作负担和再生废液对环境的污染。     

核电厂智能诊断方法研究的进展

文章评述神经网络、模糊逻辑和专家系统3种典型的智能方法在核电厂(NPP)运行状态监测和故障诊断中的应用研究进展.分析了基于神经网络(ANN)、模糊逻辑和专家系统的核电厂运行状态监测和故障诊断方法的研究状况及其特点.探索了核电厂智能诊断方法应用研究的发展趋势.分析表明:基于模糊逻辑和专家系统的核电厂智能诊断方法的研究成果相对较少;核电厂智能诊断方法研究主要集中在基于神经网络的状态监测与故障诊断方面;多种智能诊断方法的结合、神经网络与其它方法的结合,以及基于多神经网络的核电厂运行状态监测和故障诊断方法研究是核电厂智能诊断方法研究的重要发展趋势.     

除氧器水位控制的人-机接口设计研究

基于人因工程（HFE）的设计原则,以核电厂二回路主给水除氧器系统为例进行性能需求分析,得到不同层次的静态功能数据库,确定了主给水除氧器系统运行所需的基本信息流及其处理要求。为应对核电厂冷态启动、低负荷和高负荷工况下的操作要求,通过建立给水加热和除氧功能（F01）模块图和运行模式表,明确与控制室有关的功能因素。基于功能分配原则对除氧器水位控制进行研究,实现水位控制的无扰动过渡方案,通过了人-机接口设计验证,为国内开展HFE分析研究提供借鉴。      

卡利纳循环在核电厂二回路系统的应用探讨

在朗肯循环的基础上,介绍了卡利纳循环的特点和优势,简述了卡利纳循环在国外的发展概况,从理论上重点分析和阐述了卡利纳循环应用于核电厂二回路系统的可行性.结论表明,应用卡利纳循环可以提高核电厂热效率10%以上,并将显著减少循环冷却水系统和回热、再热系统的投资成本.但是,核电厂二回路工质的改变将改变热力系统,将牵涉到整个热力系统设备的重新研究开发.卡利纳循环是否能够应用于核电厂二回路系统还有待进一步的研究探讨.     

AP1000主给水管道断裂事故中PRHR系统冷却能力分析

使用机理性分析程序建立包括主冷却剂系统、专设安全设施及相关二回路管道的AP1000核电厂模型,对AP1000核电厂主给水管道断裂事故进程进行计算分析。着重分析了非能动余热排出（PRHR）系统在主给水管道断裂事故工况中的瞬态响应、热工水力行为及其冷却能力,并针对PRHR系统流道阻力特性的不确定性对冷却能力的影响进行分析。分析结果表明,在主给水管道断裂事故中,PRHR系统的热移出功率最终能够与堆芯的衰变功率相匹配,有能力带走衰变热,保证一回路系统最终处于安全停堆状态,不发生堆芯损伤,当PRHR系统阻力系数增加时,PRHR系统的流量和换热功率会降低,对PRHR系统冷却能力造成影响。     

基于RELAP5的核动力装置故障诊断数据源研究

为解决故障状态下的核动力装置数据源问题,本文建立了核动力装置一、二回路系统的模型,选择秦山一期核电站为对象,利用RELAP5对蒸汽发生器U型管破裂进行计算.通过结果分析可知所建立的模型节点划分是合理的、数据卡编制准确,基于该模型产生的数据可信.将开发的数据与基于神经网络的故障诊断系统联调,诊断测试结果表明数据准确、充分,可以为核动力装置的故障诊断系统的研究提供数据支持.     

美浜核电厂2号机组发生泄漏

【日本关西电力公司网站2003年5月21日报道】 日本关西电力公司美浜核电厂2号机组(压水堆,额定电功率为500 MW,额定热功率为1456 MW)在以额定热功率运行的过程中,二回路给水系统B系统利用第5高压给水加热器(为加热送入蒸汽发生器的二回路冷却水而设置的U形管热交换器。它是通过高压汽轮机排出的蒸汽加热传热管内流动的二回路冷却水的装置。完成加热工作的蒸汽变成冷凝水,回到给水系统。)的冷凝水流量出现了微增的倾向。于是,工作人员从5月8日开始加强了对各种相关参数的监控,发现冷凝水流量微增的倾向仍在继续,因此断定故障的最大可能是…     

AP1000核电厂主给水管道断裂事故瞬态特性分析

AP1000是目前国际上典型的“三代”非能动核电厂,基于最佳估算程序RELAP5/MOD3.3,对AP1000核电厂系统进行了详细的建模分析,获得了主给水管道断裂事故下AP1000核电厂关键参数的瞬态特性和非能动系统响应特性。结果表明,事故过程中一、二回路的压力和温度呈现波动变化,一回路压力最大值为17.13 MPa,低于设计压力的91%,主蒸汽系统的压力也低于设计值的91%,满足验收准则的要求。     

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。     

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%。     

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.     

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.