Non-Maxwell velocity distributions in inhomogeneous materials

Determining velocity distribution functions for ensembles is one of the most fundamental problems in statistical mechanics. In this paper, based on the results of computer molecular dynamics (MD) methods, we point out that the velocity distribution of low-mass classical particles subjected to a strong force field in a heavy atom environment is generally noncanonical. When the system reaches equilibrium, a non-Maxwellian distribution persists. The effective temperature of some of the low-mass particles may be one or two orders of magnitude greater than the average temperature of the system. Cold fusion may thus be enhanced by as much as 30–50 orders of magnitude over that calculated on the basis of 300K Maxwell distributions.     

Time dependence of linear stability parameters of a BWR

In this work we present several tools to study the time dependence of the linear stability parameters of a BWR using neutron noise analysis. Particularly, we have studied the variation in time of the fundamental frequency of a signal using the short-time Fourier transform and we have compared this method with the calculation of a time dependent Power Spectral Density (PSD) function. The temporal variation of the decay ratio is analysed using a method based on an autoregressive model to fit the different blocks of the signal. The performance of the tools presented is compared analysing analytic signals and a real signal of Forsmark 1&2 Stability Benchmark.     

磺酸型阳离子交换膜的性能研究

通过辐照接枝法在高密度聚乙烯(HDPE)上引入磺酸基团,从而制备了一种强酸性阳离子交换膜。就所制备离子交换膜的热稳定及化学稳定性能进行了详细考察。结果表明,接枝膜上引入磺酸基团后抗氧化性能较仅含羧酸基团的离子交换膜有所提高,接枝膜的热稳定性较之接枝前稍差,热重分析表明,接枝后样品的成碳量较接枝前有相当大的提高,原因归结于表面接枝层对成碳过程有促进作用。由于接枝膜中HDPE组份的“结晶破坏”及接枝链对晶区的“稀释作用”综合影响,结晶度随着接枝率的升高而降低。     

Semi-physical identification of dynamic properties in a thermohydraulic channel

The aim of this work is to investigate whether it is possible to extract information from process noise measurements by combining physical knowledge with system identification methods. This could be used for implicit measurements of process variables, tuning the model in a multidimensional parameter space, or simply for increasing our knowledge of the dynamical process, for example BWR stability.     

Analysis of Core Stability Measurement Data of Advanced 9×9 Fuel Assembly in a BWR Core

The core stability measurements were taken during the cycle-9 startup of the 1,300MWe BWR, Kernkraftwerk Kruemmel (KKK). The core contained advanced 9×9 type high burn-up design reload fuel with a higher enrichment than current 8x8 fuel. A design feature of the advanced 9x9 fuel assembly (FA) is a large square water channel for enhanced neutron moderation. The measurement data as a function of core flow and power showed almost the same stability characteristics as those of the past measurement during the cycle-3 startup of the KKK core with the 8×8 FA. The local power range monitors (LPRM) detected neutron flux oscillations in both core-wide in-phase and half-core out-of-phase modes.

The frequency-domain stability analysis using the STAIF-PK code well reproduced the measurement result that the onset of unstable operation in KKK first occurs when about half of the reactor internal pumps are operating and the other half are stopped. The stability performance of the advanced 9×9 FA in the core was compared with the 8×8 FA by a design parameter analysis with respect to thermal-hydraulic and neutronic design. It has been demonstrated by the analysis that the stability performance of the advanced 9×9 FA is comparable with current 8×8 FA.     

Design of Balanced Reactor Welded with Water-Cooled Aluminum Busbars

A new process of welding aluminum water-cooled busbars is proposed. It can not only reduce the weight and cost, but also improve the dynamic and thermal stability. Furthermore, both finite element method analysis and a prototype test testify the advantages of the design which is not limited by load current and provides a new approach for water-cooled reactors.     

装有稳压仪的电子静电加速器运行情况

随着辐射加工技术的发展,在国内,小功率的电子静电加速器也越来越多地用于工业生产,并要求加速器长期稳定运行。为此,于85年初,在我们的加速器上装上了由上海原子核所研制成功的稳压仪,到目前为止,加速器运行稳定。     

Preliminary Design and Analysis of the DC Reactor for the ITER Converter

The DC reactor is an important piece of equipment for restraining loop and ripple currents in the international thermonuclear experimental reactor （ITER） converter power supply system. As the reactor is operated at a steady state of 27.5 kA and needs to withstand a peak current of 175 kA, so the design of the DC reactor used in the ITER converter power supply system is necessary. A new water-cooling dry-type air-core reactor is designed in this work. The detailed structural parameters are calculated by theoretical formulas, and then the structure is optimized by electromagnetic simulation with ANSYS. Finally, thermal and dynamic stability analyses are performed to verify the temperature and stress at a rated current of 27.5 kA and pulsed current of 175 kA. The analysis results show that the temperature and stress meet the requirements of the ITER converter power supply system.     

基于Nyquist准则的超临界水冷堆热工水力系统稳定性分析

针对超临界水冷堆热工水力系统简化模型,采用微扰动线性化及Laplace变换的方法,对热工水力系统的非线性守恒方程进行线性化处理,推导出闭环系统传递函数。用Matlab软件对闭环系统进行了分析和仿真,得到模型闭环系统的稳定边界图,并分析了堆芯入口流速、加热段长度、重力加速度、入口节流系数对系统稳定边界的影响。结果表明,增大堆芯入口流速、加热段长度、重力加速度有利于系统的稳定,而入口节流系数对稳定性边界影响不大。     

低压流气系统稳定度研究

一、前言低压流气系统在平行板雪崩室、低压正比室以及基于气体电离室、正比室的焦面探测器和重粒子探测器中被广泛地应用,同时在一些化工及其他现代工业中要求高稳定流气气氛的工艺中也有很大用途。基于浮子稳压器的低压流气系统有制作简单,使用方便等优点,本文通过一些实验以及实验和理论估计的对比找出了提高流气系统工作气压稳定度的一些条件,为制造高稳定度流气系统提供了一点经验。     

高分辨率HPGe探测器及其稳定性

半导体探测器具有良好的能量分辨率,在能谱分析中已引起人们广泛的兴趣。Si材料原子序数(Z=14)较小,探测能量大于30keV的射线时,其效率迅速下降,因此人们选用Ge(Li)探测器。但它在制造和使用中存在两个主要的问题,一是必需用Li离子补偿Ge材料,二是Li在Ge中固有的不稳定性,使器件严禁升高到室温,即使是偶然的一次,也会导致器件的补偿度毁坏。这两个缺点,在用高纯Ge材料制备的探测器(HPGe探测器)中是不存在的,     

池式钠冷快堆堆芯系统动态特性和稳定性的仿真研究

参照我国实验快堆初期的概念设计，采用了模块化结构建立了一种池式快堆堆芯一次系统的数学模型，运用ＭＡＴＬＡＢ仿真语言及ＳＩＭＵＬＩＮＫ仿真工具编制堆芯一次系统的动态过程仿真程序，并着重分析了堆芯的动态特性及稳定性。     

压水堆堆芯非线性系统的全局稳定性分析

判定压水堆堆芯非线性系统的全局稳定性是待解决的问题。建立了压水堆堆芯非线性系统,利用微小摄动方法求取其线性化模型。依据基于平衡流型的堆芯非线性测度在功率水平域内的分布情况,选择7个功率水平处的线性化模型作为堆芯局部模型,以局部模型组合来近似替代堆芯非线性系统。利用Lyapunov稳定性理论,分析堆芯非线性系统全局稳定性。计算结果表明：压水堆堆芯非线性系统是全局渐进稳定的;在判定堆芯系统全局稳定性时,这种非线性系统的建模方法是有效可行的。     

脉冲堆的自稳定性计算

介绍一种用于脉冲堆自稳定性分析的计算方法－增广矩阵法,并用该方法编制程序进行仿真计算,又将本计算结果与相应物理计算结果进行了比较,比较表明：该方法是有效的,计算结果也符合有关设计准则的要求。     

Thermal and Stability Considerations of Super LWR during Sliding Pressure Startup

The feasibility of the sliding pressure startup of a high-temperature supercritical-pressure light water reactor (super LWR, SCLWR-H) is assessed from both thermal and stability considerations. In the sliding pressure startup, nuclear heating starts at subcritical pressure and the reactor is pressurized to supercritical pressure at a low power and high enough flow rate. The reactor power and flow rate are then raised gradually to the rated normal values at constant supercritical operating pressure. During startup, the maximum cladding surface temperature must not exceed 620°C. For two-phase flow at subcritical pressures, the homogeneous equilibrium model is used. The thermal-hydraulic and coupled neutronic thermal-hydraulic stabilities during pressurization and power-raising are investigated by a frequency-domain linear analysis for both supercritical-pressure and subcritical-pressure operating conditions. The same stability criteria as those of BWRs are used. From the analysis results, a sliding pressure startup procedure is proposed for super LWR. The thermal criteria are satisfied by keeping the core power between the maximum allowable limit and minimum limit required for turbine startup and operation. The thermal-hydraulic stability and coupled neutronic thermal-hydraulic stability can be maintained by applying an orifice pressure drop coefficient at the inlet of fuel assembly and by controlling the power and flow rate during startup.     

18F-FDG的稳定性及提高稳定性的方法

本工作研究了常规制备的大剂量、高浓度¹⁸F-FDG的稳定性,并在产品中添加稳定剂乙醇或对已部分分解的产品进行再纯化,以提高¹⁸F-FDG的放化纯度。结果显示,当¹⁸F-FDG产品浓度高于6 TBq/L时,放置4 h,其放化纯度＜95%;浓度大于7.4 TBq/L时,添加体积分数为0.1%的乙醇后,能明显降低¹⁸F-FDG的分解,6 h后放化纯度＞95%;已分解的¹⁸F-FDG经再纯化后,放化纯度＞99%。Micro PET/CT大鼠显像表明,采用已分解的¹⁸F-FDG对大鼠进行显像,其股骨有明显摄取;对其进行再纯化处理后对大鼠显像,大鼠股骨无放射性摄取。以上结果表明,高浓度的¹⁸F-FDG有效时间小于4 h;添加0.1%乙醇可明显减慢高浓度¹⁸F-FDG分解,而再纯化方法可以彻底除去分解的放射性杂质。为保证¹⁸F-FDG质量,将添加稳定剂和再纯化两种方法联合使用,保证产品放化纯度的同时还可提高¹⁸F-FDG的利用率。     

低参数直流蒸汽发生器稳定性实验研究

针对核供热堆的低温、低压运行条件，建立了大盘管直流蒸汽发生器热工水力学实验系统，实验研究了低参数条件下入口流动阻力、运行负荷和蒸汽发生器出口压力对直流蒸汽发生器稳定性的影响。结果表明：入口节流阻力比、运行负荷、系统压力对直流蒸汽发生器稳定性有影响，通过调整入口节流阻力比，直流蒸汽发生器可在低压参数下稳定运行。     

高稳定度电源电压基准研究

介绍了高稳定度电源对电压基准的要求，及电源的高稳定度与电压基准的关系，研究了电压基准在电压驱动器件和电流驱动器件情况下的线性问题，给出了实现高稳定度电压基准的两种方法。     

一个机组供电的晶体管稳流电源

1983年我们制作了一台由机组供电的晶体管稳流电源,取代原苏制BT-4稳流装置,作为ЭГ-2.5质子静电加速器分析磁铁的激磁电源。主要技术指标为:(1)额定输出直流电压100 V;(2)额定输出直流电流30 A;(3)电流调节范围0—30 A;(4)电流稳定度为±1.4×10~(-5)(当负载变化±10%时),±1.0×10~(-5)(当电网电压变化±10%时);(5)长时间漂移为2.3×10~(-5)/h,5.26×10~(-5)/8 h;(6)电流纹波为8.7×10~(-5)。     

~(67)Ga-C_(60)(OH)_x标记条件的研究

用^67Ga标记了水溶性富勒烯衍生物富勒醇（C60（OH）x）。研究了反应时间、温度、pH值、C60（OH）x的质量浓度等对标记率的影响。研究结果表明，反应时间在3-60min时对标记率影响不大；反应温度对标记率基本无影响；pH值大于12后，标记率较低；C60（OH）x的质量浓度高于5μg/μL时，标记率均在94%以上。稳定性研究结果表明，标记后稀释与不稀释的溶液在放置200h后，其放化纯度都达90%以上。