BP神经网络改进算法在核电设备故障诊断中的应用

根据训练误差大小自适应调整神经元输入特性参数,并应用改进的遗传算法对神经网络的权值和隐含层数目进行优化,对传统的人工神经网络误差反传算法进行了改进,使训练算法的收敛速度大大提高.将人工神经网络技术和改进的BP网络训练算法应用于核电设备故障诊断,并以核电蒸汽发生器U形管破裂为例,建立了故障诊断模型.仿真结果表明,该算法的应用是可行的.     

基于粗糙决策模型的核电厂故障诊断方法

将粗糙集和信息熵相结合,提出了改进的决策树ID3算法,并提出了基于此算法和粗糙集约简算法的故障诊断方法.将该方法用于核电厂故障诊断.结果表明,该方法具有良好的故障诊断性能,可在核电厂故障诊断领域中应用.     

低能重离子束注入小麦种子诱导根尖细胞有丝分裂畸变的研究

比较研究了低能重离子束注入小麦干种子和萌动的种子对种子发芽及根尖细胞有丝分裂畸变的影响。结果表明,离子注入对萌动的种子的发芽有明显的影响,而对干种子的发芽影响不明显。在一定剂量范围内(0-6×1016/cm2),N+注入诱导的萌动种子的有丝分裂畸变率略高于干种子,并且随辐射剂量的升高而升高;但超过一定的剂量(>6×1016/cm2),无论是干种子还是萌动种子的有丝分裂畸变率达到一定程度的饱和。就实验结果对N+离子束注入诱变的机理进行了一些探讨。     

Characterization of silicon oxynitride films using ion beam analysis techniques

Heavy-ion elastic recoil detection analysis (HIERDA) is the ideal technique for quantitative analysis of silicon oxynitride films on silicon because of its unique ability to measure simultaneously all elements of interest (i.e., H, C, N, O and Si), thereby permitting key parameters such as the O/N-ratio to be determined in a single measurement. However, high-energy accelerators suitable for such HIERDA measurements are becoming much less readily available. Hence, the present paper investigates and calibrates an alternative IBA technique for simultaneous O, N and C analysis – namely, the use of (d,p) and (d,) nuclear reactions. Under optimum analysis conditions (850 keV deuterons and 150° detector angle), the Si background level sets a lower detection limit of 1×10¹⁶ nitrogen atoms/cm² and 3×10¹⁵ oxygen atoms/cm². H analysis is carried out separately, using low-energy ERDA and a 2 MeV ⁴He beam. Absolute cross-sections have been obtained for each of the (d,p) and (d,) groups. Comparison with data in the recent Handbook of Modern Ion Beam Materials Analysis shows reasonable agreement (10–15%) for the (d,p) reactions on oxygen and carbon. However, in the case of nitrogen, the measured cross-section values are 70% larger than the Handbook data. Several silicon oxynitride samples have been analyzed, first at UWO using 850 keV deuterons, and subsequently at ANU using HIERDA and a 200 MeV Au beam. The resulting O/N-ratios agree to within 10%. The relative importance of radiation damage effects is briefly discussed.     

振动监测与分析技术在核电站中的应用

从保障核全安、提高核电经济运行水平、解决重大技术问题和预测性维修等４个方面介绍了振动监测与分析技术在核电站中的应用,并通过实例说明了振动监测及分析技术在大亚湾核电站安全,稳定,经济运行中所起的重要作用。     

某待建滨海核电厂址事故冲洗因子计算模式探讨

本文参照当前国内外常用导则给出的估算事故扩散因子的模式,提出了一套估算事故冲洗因子的确定论模式与概率论模式,并根据我国东部某待建滨海核电厂址的实测气象资料,分别估算了事故后各时段（０～８ｈ、８～２４ｈ、１～４ｄ和４～３０ｄ）的冲洗因子（确定论模式）和事故概率冲洗因子以及相应的沉积外照射剂量。结果表明,对事故后０～８ｈ时段而言,由确定论模式给出的冲洗沉积外照射有效剂量分别为相应的干沉积外照射有效剂量     

Seawater desalination plant using nuclear heating reactor coupled with MED process

A small size plant for seawater desalination using nuclear heating reactor coupled with MED process was developed by the Instituted of Nuclear Energy Technology,Tsinghua University,China,This seawater desalination plant was designed to supply potable water demand to some coastal or island where both fresh water and energy source are severely lacking ,It is also recommended as a demonstration and training facility for seawater desalination using nuclear energy. the desing of small size of seawater desalination plant couples two proven technologies:Nuclear Heating Reactor(NHR) and Multi-Effect Destination (MED) process.The NHR desing possesses intrinsic and passive safety features,which was demonstrated by the experiences of the project NHR-5.The intermediate circuit and steam circuit were designed as the safety barriers betewwn the NHR reactor and MED desalination system.Wihin 10-200MWt of the power range of the hating reactor,the desalination plant could provide 8000 to 150,000m^3/d of high quality potable water,The desing concept could provide 8000 to 150,000m^3/d of high quality potable water,The design concept and parameters,safety features and coupling scheme are presented.     

“医疗照射中的放射防护”专题介绍

由于医疗照射是公众所受到的非天然电离辐射中的最主要部分 ,而近几十年来新的放射性诊断和治疗设备不断出现 ,并且很快地被投入临床使用之中 ,因此“医疗照射中的放射防护”专题成为了 IRPA-1 0大会的主要内容。会议中各国学者分别就在放射诊断学 (包括介入放射学 )、核医学和放射治疗临床工作中 ,病人与工作人员受照剂量的测量、降低其照射剂量的方法、对健康状况的评价、质量保证 /控制工作等等问题发表了各自的论文并进行了广泛的讨论。     

核电站辐射防护的现状和趋势

核电站辐射防护的任务主要包括 :个人和集体剂量控制 ,放射性物质管理以防止失控和污染扩散 ,辐射事故预防 ,其中最能衡量核电站辐射防护管理和 ALARA实施水平的指标是集体剂量控制。控制集体剂量可以从控制剂量率水平、控制照射时间和控制受照人数 3个方面着手 ,而这 3个方面的控制又可以通过源项控制、安全文化培养、工作过程管理和优化等措施来达到。在日本举行的 IRPA-1 0上发表的有关报告 ,也表明目前的核电站辐射防护有以下 3个特点和趋势 :1 )重视核电站安全文化的培养 ;2 )重视对放射性源项的监测和控制 ;3 )重视对高风险工作过程的 ALARA控制。本文对这些方面分别进行了阐述。