中国实验快堆单组件完全堵流后钠沸腾的预测

为预测正常功率下快堆单个燃料组件的瞬间完全堵流导致的后续事故序列及其潜在的破坏能力,对模拟这种现象的SCARABEEBE 1实验在包壳流动之前的阶段进行了数值模拟。在此基础上对中国实验快堆(CEFR)在此事故工况下的冷却剂沸腾进行了预测。计算结果表明:对于CEFR,沸腾的过程中也出现了实验中观测到的出口处流量波动和通过组件盒的热流通量的快速增长。SCARABEEBE 1实验中,干涸发生之前,沸腾持续了大约2.2s;对于CEFR,沸腾开始后0.3s便发生了干涸。造成这一差异的主要原因是CEFR的燃料组件规模和单位体积的热功率更大。     

基于两区模型的钠冷快堆无保护失流事故

为了研究钠冷快堆的固有安全性,研究了适用于钠冷快堆系统分析的理论模型,根据钠冷快堆的特点开发了SAC程序。针对钠池温度计算不准确问题,提出了两区模型。利用三维模型计算钠池主流区,采用提出的两区模型计算钠池温度的瞬态响应。选取了美国实验增殖反应堆(EBR-II)的无保护失流事故实验进行计算对比分析,采用三维钠池模型对钠池流场进行计算和分析,采用两区模型有效地计算了钠池温度瞬态响应。程序计算的事故瞬态结果与实验结果符合较好,验证了SAC程序进行快堆瞬态计算的准确性,同时证明了利用金属燃料的钠冷快堆的固有安全性。     

穿透概率法求解二维六角形几何多群中子积分输运方程

讨论了用穿透概率法求解二维六角形几何轻水堆燃料组件中子通量的分布,提出了一种简易计算模型。子区内中子源采用各向同性平源分布,子区量在方向上采用简化６Ｐ１近似。根据提出的模型,编制了ＴＰＨＥＸ＿Ａ程序,并对一些轻水堆六角形组件问题作了计算,计算结果与ＤＲＡＧＯＮ程序计算结果以及ＭＣ结果进行了比较,符合较好,本程序可用于轻水堆六角形燃料组件计算。     

MCNP程序在CARR物理启动计算中的应用

 中国先进研究堆(CARR)既没有参考堆,也不进行零功率物理模拟实验,其物理启动工作完全以理论分析结果为依据,这在国内大型研究堆的启动中尚属首次。CARR堆芯结构复杂,启动过程中堆内标准燃料组件、跟随体燃料组件和贫铀组件混装,堆芯装载变化大,大部分基于扩散理论的物理计算程序较难完成CARR物理启动的理论分析工作。选用MCNP程序对CARR物理启动的各项实验进行模拟计算,该程序强大的几何描述功能很好地解决了上述难点。得到的计算结果为CARR物理启动工作提供了重要依据和参考,保证了CARR物理启动工作的安全顺利进行,实验结果表明,MCNP的计算结果准确可信,该程序在CARR物理启动工作中的应用是成功的。     

NHR-200燃料组件定位格架水力学模拟实验研究

为了掌握２００ＭＷ核供热堆定位格架对燃料组件阻力系数的影响,采用１１的实验本体,模拟条件为几何形状,雷诺数相同,在ＨＲＨＴＬ－２００水力实验回路上完成本实验研究。描述了实验本体的设计及制作方法,研究了燃料组件进口节流孔板在开孔直径分别为７０ｍｍ,９０ｍｍ和１１０ｍｍ条件下,燃料组件及模拟定位格架的流动阻力特性。分析了定位格架对燃料组件阻力系数的影响。实验还研究了有、无定位格架时棒束机械振动对燃料组件阻力系数的影响。实验结果表明棒束机械振动对燃料组件阻力系数的影响可以忽略。研究结果可直接用于２００ＭＷ核供热堆的热工水力学设计。     

一种快堆边界下的裂变气体释放数值模型

裂变气体释放(FGR)对燃料元件的热力演化过程有着极其重要的影响,准确地模拟反应堆中裂变气体释放是燃料元件性能分析程序开发的最基本内容之一, 也是重要的评价准则. 本文围绕快堆边界下的裂变气体释放行为展开详细论述,基于气体原子与气泡行为模型,模拟了晶内气体原子的产生、自由扩散、俘获-再溶解等行为,以及晶内气泡的形成、生长、融合、移动等行为.模拟了晶界气泡的生长、连接、通道形成与气体释放等过程. 通过数值方程组离散和迭代计算,建立了一种快堆边界下的裂变气体释放数值模型. 经过与理论及实验数据对比,结果显示该模型能准确预测燃料元件的裂变气体释放份额与气体肿胀量,能较好地模拟晶内气泡浓度与尺寸. 表明该模型可以用于快堆燃料元件性能分析.     

二维轻水堆燃料组件中子通量和功率分布的计算

本文讨论二维轻水堆燃料组件内中子通量和功率分布的计算。文章第一部分讨论穿透几率方法,提出了一种简易的计算模型。在子区内,中子通量采用线性分布,子区表面上采用P_1近似角分布和线性空间分布,对展开系数导出了简便的表达式,即用表面上的出射和入射中子流来决定,并在迭代过程中逐步更新和精确化,因而减少了求解的未知量,简化了计算。文章第二部分讨论块方法的应用以及栅元等效圆柱化的误差。根据提出的模型,编制了二维TPM2D和BTM计算程序。对轻水堆的一些组件基准问题作了计算。计算结果与其它方法进行了比较,其结果符合得很好。本程序可用于轻水堆燃料组件的计算。     

定位检测破损燃料组件的堆芯啜吸法

破损燃料组件定位检测系统是为了确保反应堆安全运行、及时处理燃料包壳破损事故的安全重要设备.根据目前国际上对有元件盒反应堆采用的堆芯啜吸法,即在反应堆换料期间或发生燃料包壳破损事故时,停堆后直接从仍在堆芯位置的元件盒中取样,进行放射性测量和分析,从而鉴别出有破损的燃料组件的方法,作者设计了200MW低温核供热堆破损燃料组件定位检测系统.该设计既有国际同类设备的先进水平,又结合了低温核供热堆的特点和我国国情,保证了200MW低温核供热堆的安全.     

板状燃料组件流致振动实验研究

针对贫铀叠层板型燃料组件,采用了基于虚拟仪器的软测量方法,在常温、常压下,进行了其在经受冷却剂冲刷时的振动实验。获得了该组件在0～18.8m/s流速下的流致振动动态响应时间域和频率域结果。实验结果表明:燃料组件在流体冲刷下的振动频率包含各种频段,几乎没有主频;组件的行为包含振动和偏移两个方面,偏移量占主要部分,振动量占次要部分;随着流速的增加,燃料组件的振动和偏移不断增加;在整个0～18.8m/s流速范围没有出现流体弹性不稳定的大振幅振动。     

不锈钢陶瓷复合管材剪切过程数值模拟

快堆乏燃料组件进入快堆乏燃料后处理工艺流程的第一步便是剪切解体,因辐射的制约,通常使用不锈钢模拟元件包管和陶瓷模拟燃料芯棒进行实验。将不锈钢模拟元件包管和陶瓷模拟燃料芯棒并组成复合管材模型模拟单根快堆乏燃料组件,根据非线性有限元分析软件Abaqus中Johnson-Cook本构模型与Johnson-Holmquist ceramic(JH-2)本构模型构建不锈钢陶瓷复合管材的材料模型,模拟其剪切断裂过程,并研究不锈钢陶瓷复合管材在剪切过程中断裂损伤失效过程中受力变形情况,以及刀具进给速度、剪切间隙对剪切力的影响。结果表明最大剪切力随进给速度增大而增大,随剪切间隙增大呈现先增大后减小的趋势,能为组件剪切方案和剪切机设计提供参考。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that