A Fat strange Repeller

This article reports an observation on a fat strange repeller, which appears after a characteristic crisis observed in a kicked rotor subjected to a piecewise continuous force field. The discontinuity border in the definition range of the two-dimensional mapping, which describes the system, oscillates as the discrete time develops. At a threshold of a control parameter a fat chaotic attractor suddenly transfers to a fat transient set. The strange repeller, which appears after the crisis, is also a fat fractal, This is the reason why super-transience happens     

An investigation into the nature and significance of a new critical heat flux correlation

An empirical critical heat flux correlation, which is based upon dimensionless groups, and which was developed from a wide range of experimental data for vertical upflow in uniformly heated tubes, has been further examined to determine if, because of its accuracy and generality, it might provide an insight into the mechanisms of boiling crisis. A parameter survey using the correlation showed that it was well able to predict the so-called ‘crisis of the second kind’ without needing to define any separate or distinct flow regimes.Comparison of the empirical correlation with a general form of theoretical correlation, developed from a combination of several simple physical models which occur during the crisis phenomenon, shows a strong similarity in the form of the dimensionless groups. It also indicates that a further dimensionless group may need to be incorporated in the empirical correlation to achieve complete generality.Rearrangement of the dimensionless groups and the form of the empirical correlation, together with some minor approximations, indicate that boiling crisis is influenced by local hydrodynamic and thermal phenomena and can be related to pre- and post-crisis coolant conditions.     

棒束通道定位格架沸腾临界特性数值研究

为研究核反应堆中定位格架及搅混翼对沸腾临界现象产生的影响,本文采用计算流体动力学（CFD）分析方法,探讨了棒束通道中定位格架的数目、位置和搅混翼的角度对于沸腾临界现象的影响。结果表明:定位格架会对主流流动产生阻力,同时定位格架数目越多,沸腾临界发生的温度也越高,但将定位格架布置在沸腾临界发生位置时,则可有效改善壁面传热环境并降低沸腾临界发生时的峰值温度。搅混翼的存在则会有效降低加热面附近空泡份额,改善传热环境,但搅混翼角度过大时会导致沸腾临界提前发生。      

Review of two-phase flow instability

Boiling flow in a water-cooled reactor, an evaporator, or an electronic cooling system is susceptible to thermal-hydrodynamic instabilities, which may cause flow oscillations of constant amplitude or diverging amplitude. These oscillations could induce boiling crisis, disturb control systems, or cause mechanical damage. This paper identifies the causes and mechanisms of these instabilities. Based on their mechanisms, various types of instabilities are classified and tabulated. The parametric effects on flow instability, observed experimentally, are systematically presented. Various analytical techniques for predicting the instability threshold are reviewed in terms of their applicability and accuracy.     

The need for further nuclear safety research: A present French view

The Chernobyl accident strengthens once more the need for a high level of safety for nuclear plants. We can still improve this safety both by operational feedback and by research which must be considered as an important and continuous way of progress.A review of the French evolution in safety research is presented, with special attention paid to the actions accelerated after Chernobyl (venting system for containment building, Phebus Fission Products, Ressac) and to those being considered recently after this accident.Finally, if the Chernobyl accident did not modify in depth the safety research priorities settled after TMI, it stresses the need to maintain strong support to research and to prepare the means capable of dealing with an emergency situation and efficient crisis management.     

Development of the bunch-by-bunch beam position acquisition system based on BEEcube

In this paper, we report the development of a bunch-by-bunch beam position acquisition system.Through a wideband synthesizer of PLL, the system realizes synchronous clock of bunch signal. Based on the highperformance FPGA hardware DAQ environment, fourchannel raw data of beam signal can be achieved. Test results in the SSRF storage ring show that the system can obtain beam position of single bunch with the resolution of10 lm and multi-bunch instability can be observed.     

Transmutation of nuclear waste in accelerator-driven systems: Fast spectrum

The elimination of nuclear waste is currently a pressing issue in view of the global energy crisis and increasing radiotoxic waste inventories. One potential and well-researched solution to these issues is to transmute nuclear waste in a thorium-based accelerator-driven system, such as the energy amplifier.     

EAST全超导托卡马克上硅漂移探测器软X射线能谱诊断

采用性能优越的15道硅漂移探测器（SDD）阵列,在EAST全超导托卡马克上建立了1套较为完善的软X射线能谱诊断系统,用以测量等离子体在软X射线辐射能段(1～20keV)的能谱。该诊断系统的观测范围基本覆盖了整个等离子体空间,因此,可满足EAST不同放电位形下电子温度测量的要求。利用该诊断系统,可获得时间分辨达50ms、空间分辨约为7cm的电子温度剖面。通过对比发现,由该诊断系统所得到的电子温度与其它电子温度诊断系统所测量的电子温度基本一致。此外,该诊断系统还可监测在软X射线能量范围内出现的一些金属杂质的特征线辐射。     

Pattern Formation in a Dusty Plasma System

A rich variety of dust patterns have been observed in a capacitively coupled rf discharge dusty plasma system. Dust particles are synthesized through chemical reaction of the filled gas mixture during discharge. Different patterns are formed in different stages of particle growth. In the early stage of particle growth, dust cloud can be formed by a large number of small particles, and its behavior appears to be fluid-like. Such interesting nonlinear phenomena as dust void and complex dust cloud patterns are observed in this stage. As dust particles grow, the particle size and structure can be controlled to follow two different routes. In one of the routes, the particles grow up in a ball-like shape and can be formed into regular lattice and cluster patterns. In the other, the particles grow up in a fractal shape.     

ARM计算环境下堆芯程序CORTH和KYLIN2的移植

为了论证国产芯片在堆芯数值计算领域的可行性,对子通道计算软件CORTH和堆芯组件程序KYLIN2的串行版本在飞腾处理器的ARM计算环境进行了移植。移植过程在ARM计算环境下通过合理的程序代码修订,去除对商业函数库的依赖,且在特征线循环结构的扫描计算过程引入OpenMP多线程并行。实验参照对象为频率两倍差异的Intel商用处理器。结果表明CORTH程序和KYLIN2均能够成功移植,且与Intel商用处理器的数值稳定性保持一致。计算效率方面CORTH程序移植后的串行效率与Intel计算环境差异较小;KYLIN2移植后的串行效率较低,但通过线程并行后计算效率接近Intel处理器的串行效率。移植结果论证集群系统这种混合国际和国内处理器的资源结构,能够在计算资源紧张的情况下充分利用国产硬件,提升计算环境的整体利用效率。     

Reaction Rate of Hydrolysis of Iodine

Absorption rates of dilute iodine vapor contained in air by aqueous mixtures of sodium hydroxide and boric acid were measured using a laminar liquid jet column absorber at 298 K. Absorption rates in this system are controlled by a series of complex reactions taking place in the liquid phase. The reaction rate constant of iodine hydrolysis in the aqueous phase was determined from the absorption rates observed under the conditions that the base-catalytic hydrolysis reaction of iodine can be considered to be irreversible and that other reactions can be neglected. The absorption rates calculated theoretically with the rate constant value obtained above were in good accordance with the whole experimental data observed for a wide range of experimental conditions.     

基于HMM&SVM的核动力设备机械故障诊断方法研究

核动力设备复杂且积累的资料与故障样本少,传统的诊断方法有待改进。隐马尔可夫模型与支持向量机是一种新的智能诊断技术。本文针对核动力设备机械故障诊断的特点,采用隐马尔可夫模型建模的方式进行故障的初步诊断,再利用支持向量机小样本的强推广能力进行进一步甄别。主泵故障模拟装置上的验证实验表明,HMM&SVM混合模型具有较高的故障识别率。     

Development of a radiation-monitoring and emergency-response system in the Murmansk region

Approaches to developing a radiation-monitoring and emergency-response system in the Murmansk region, taking account of the latest changes in the applicable laws, are examined. The requirements for creating and organizing a response to an emergency and interaction wth emergency services are listed, the role and problems of territorial crisis information centers are determined, a typical structure of the radiation-monitoring and emergency-response system is developed, and the current status and prospects for future development in the Murmansk region are described. __________ Translated from Atomnaya énergiya, Vol. 101, No. 1, pp. 69–76, July, 2006.     

核与辐射事故时的心理变化及干预措施

核与辐射事故不仅能严重威胁公众生命财产,同时还会引起一系列与应激有关的心理危机。本文简要介绍了核电史上数起重大核与辐射事故及其危害,以及人们在核与辐射事故中的心理变化,总结并提出核事故心理应激的干预措施。     

Two-phase flow instability in a parallel multichannel system

The two-phase flow instabilities observed in through parallel multichannel can be classified into three types, of which only one is intrinsic to parallel multichannel systems. The intrinsic instabilities observed in parallel multichannel system have been studied experimentally. The stable boundary of the flow in such a parallel-channel system are sought, and the nature of inlet flow oscillation in the unstable region has been examined experimentally under various conditions of inlet velocity, heat flux, liquid temperature, cross section of channel and entrance throttling. The results show that parallel multichannel system possess a characteristic oscillation that is quite independent of the magnitude and duration of the initial disturbance, and the stable boundary is influenced by the characteristic frequency of the system as well as by the exit quality when this is low, and upon raising the exit quality and reducing the characteristic frequency, the system increases its instability, and entrance throttling effectively contributes to stabilization of the system.     

On mass transport in nuclear carbides by evaporation-condensation

Self-diffusion studies in the UC system show a mass transfer between diffusion specimens. This phenomenon is shown to be due to rate-controlling metal-atom transport through the gas phase by evaporation-condensation, and fast carbon transport through solid-state diffusion. The activation energy of the process being about 5.0 eV is thus in agreement with literature data on the heat of vaporization of U from UC. The mass transfer can be measured very accurately and vapor pressures can be deduced. The same mechanism can also explain the observed pore mobilities in nuclear carbide fuels.     

单棒通道流动振荡诱发沸腾临界可视化实验研究

为深入分析沸腾两相流动振荡诱发沸腾临界的影响特性,本文以去离子水为工质,横截面19 mm×19 mm、中心为外径9.5 mm的单棒通道为研究对象,通过在不同热工参数下开展沸腾两相流动特性可视化实验研究,结合汽泡行为和汽-液界面特性,分析流动振荡诱发沸腾临界的影响特性。研究结果表明,低压力、低质量流速和低入口过冷度下,极易出现流动振荡,并导致沸腾临界提前发生,此时的临界热流密度与稳定工况下相比明显偏低;随着壁面热流密度不断增加,流道中两相流型先后出现泡状流、弹状流、合并弹状流、搅混流、剧烈搅混流、不稳定环状流;当流动出现剧烈振荡时,流道存在回流;发生沸腾临界时流道压降波动最大,对应的流型为不稳定环状流。因此,单棒通道内流动振荡可能会导致沸腾临界提前发生。      

Some uses and limitations of fuzzy logic in artificial intelligence reasoning for reactor control

This paper describes some potential uses for Fuzzy Logic as well as its limitations based on experience designing a small prototype expert system that can be used in a computer laboratory to study a government research reactor. The expert system designed in this study diagnoses problems in the interface between the heat exchanger and the core. Engineers who had first-hand experience with the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory suggested logical relations incorporated in the knowledge base. The expert system has a production rule backward-chaining-based architecture, and the knowledge base incorporates four kinds of information. First, the structural relationship between causes and consequences are given by nuclear engineering experts. Second, numerical values for the initiating events can be taken from observed performance of the HFIR during normal conditions. Third, the causes of particular events are ordinally ranked by their expected chance of occuring based on a combination of knowledge about the reactor design and actual experiences with the reactor in operation. Fourth, Bellman-Zadeh Fuzzy Logic is introduced to maintain truth values for expert system parameter values that can be true with some degree of certainty.     

气载碘在农作物、草和土壤中的沉积及其吸收和易位实验研究(英文)

为了深入了解放射性碘在亚洲生物圈中的迁移规律,建立了一个封闭的实验系统,进行气载125I释放后在作物和土壤的沉积和吸收规律实验。盆栽实验的结果表明,(1)125I气溶胶在农作物上的沉积主要是干沉积;(2)沉积在农作物上的125I可以通过叶面吸收转移到其他组织中;(3)玉米和菜豆的易位因子最大。125I从土壤到农作物的吸收实验表明,沉积在土壤中的125I能够通过根部吸收转移到农作物中,125I在小米和高粱中的转移系数明显高于其他作物。     

Experimental investigation on narrow gap heat transfer with porous media under downward-facing horizontal heated surface

An experimental study of horizontal narrow gap heat transfer of porous media under a round downward-facing heated plate has been carried out, using water as the working fluid. The boiling curves are obtained with different gap size, plate diameter and solid spherules. The results show that the heat transfer increases significantly with porous media in the gap especially under boiling condition, and the occurrence of pool boiling crisis would be brought forward when the gap size is very small. The results also indicate that the heat transfer in horizontal narrow gap can be enhanced by increasing the ratio of gap size to plate diameter and using porous media with high thermal conductivity. Based on the mechanism of heat transfer of porous media, the correlations for natural convection and nucleate boiling are proposed to predict the heat flux.