Applicability of the Diffusion and Simplified P3 Theories for Pin-by-Pin Geometry of BWR

The pin-by-pin fine-mesh core calculation method is considered as a candidate next-generation core calculation method for BWR. In this study, the diffusion and simplified P3 (SP3) theories are applied to the BWR pin-by-pin fine-mesh calculation. The performances of the diffusion and SP3 theories for cell-homogeneous pin-by-pin fine-mesh calculation for BWR are evaluated through comparison with a cell-heterogeneous detailed transport calculation by the method of characteristics (MOC). Two-dimensional, 2 × 2 multi-assemblies geometry is used to compare the prediction accuracies of the diffusion and SP3 theories. The 2 × 2 multi-assemblies geometry consists of 9 × 9 UO₂ fuel assemblies that have two different enrichment splittings. To minimize the cell-homogenization error, the SPH method is applied for the pin-by-pin fine-mesh calculation. The SPH method is a technique that reproduces a result of heterogeneous calculation using that of homogeneous calculation. The calculation results indicated that the diffusion theory shows a discrepancy larger than that of the SP3 theory on the pin-wise fission rate distribution. In contrast to the diffusion theory, the SP3 theory shows a much better accuracy on the pin-wise fission rate distribution. The computation time using the SP3 theory is about 1.5 times longer than that using the diffusion theory. The BWR core analysis consists of various calculations, e.g., the cross section interpolation, neutron flux calculation, thermal hydraulic calculation, and burn-up calculation. The function of the calculation time for the neutron flux calculation is usually less than half in the typical BWR core analysis. Therefore, the difference in the calculation time between the diffusion and SP3 theories would have no significant impact on the calculation time of the BWR core analysis. For these reasons, the SP3 theory is more suitable than the diffusion theory and is expected to have sufficient accuracy for the 2 × 2 multi-assemblies geometry used in this study, which simulates a typical situation of the actual BWR core.     

长距离高落差重力流供水工程的关阀水锤

对长距离高落差重力流供水工程中阀门动作规律进行了研究,分析了关阀的水锤特性,运用特征线法推导了在已知阀门关闭规律时管道首相水锤压力的解析公式以及在已知管道控制压力时阀门最快直线关闭规律的解析公式,并结合数值计算对公式的正确性进行检验。结果表明:推导出的首相水锤压力解析公式和水锤直线关阀规律解析公式计算均与数值计算结果吻合较好,精度较高,可为高落差重力流供水工程的管道设计及运行调度提供参考。     

Influence of molar ratios on properties of magnesium oxychloride cement

A parametric study has been conducted to investigate the influences of the molar ratios of MgO/MgCl₂ and H₂O/MgCl₂ on the properties of magnesium oxychloride (MOC) cement. By an integrated assessment of the experimental studies of strength development and X-ray diffractograms, together with application of the relevant phase diagram, it is recognized that the molar ratios of MgO/MgCl₂ and H₂O/MgCl₂ can significantly affect the properties of MOC cement. For a MOC cement paste possessing a dominance of 5MgO·MgCl₂·8H₂O (phase 5) crystals, the molar ratios of MgO/MgCl₂ of 11-17 and H₂O/MgCl₂ of 12-18 are found to be the most favorite ranges for design purpose. The choose of the molar ratio of H₂O/MgCl₂ is, however, largely depends on the molar ratio of MgO/MgCl₂ mainly for controlling workability of paste. Therefore, the most critical parameter to be selected in the design process is the molar ratio of MgO/MgCl₂, although the reactivity of the MgO powder is also important. Besides, the molar ratio can also be affected by the reactivity of the MgO powder to be employed. It is believed that a molar ratio of MgO/MgCl₂ of 13, the most suitable one shown in this study, can be used as a starting point in the normal practice.     

基于可靠度的分级电价定价模型研究

建立科学合理的电价模型是电力市场研究的重要内容。本文首先将供电可靠度分成若干个等级，通过构造电力充足概率来衡量不同的可靠度等级，并以此分摊容量成本。从用户的利益出发，在边际电量成本中，考虑了边际缺电成本。应用边际定价理论，给出了分级定价的数学模型。最后通过在电价中考虑征罚项，确立了事故受害方的缺电成本的承担问题，制定了事故缺电定价模型。分级电价模型考虑了可靠度和缺电成本，通过电价的调节功能达到负荷管理的目的。     

A general kinetic model framework for the interpretation of adiabatic calorimeter rate data

Notwithstanding the variety and complexity of the reactions studied by adiabatic calorimeters like ARC, the data interpretation techniques are not general enough. Traditional thermokinetic analysis primarily lumps a complex multi-step reaction into a single overall reaction and ignores possible thermal effects in some of the possible side reactions. With detailed chromatographic/mass spectrometric analysis of the headspace gases and the condensed phase residues, the pressure profile becomes an additional source of identification of the mechanism and the kinetics of the overall reaction. Finally, in the context of new multiphase catalytic processes of greater efficiency and environment friendliness and with reference to the storage of potentially incompatible fluid mixtures in metallic containers, ARC studies of heterogeneous reaction systems are becoming part of the mandatory safety evaluations. With a few additional measurements a proper kinetic interpretation of the ARC data on such systems seems possible. The paper presents a general model that was shown to be easily adaptable to a number of published reactions of various complexities referred to above. Standard thermal hazard characteristics like the onset temperature, adiabatic temperature rise, self-heat rate, time-to-maximum rate, pressure–temperature profile, etc. could be accurately calculated by the model and these compared closely with the experimental data. It is hoped that the model would be useful as a general-purpose tool for the interpretation of adiabatic calorimetric data for the purpose of process hazard assessment.     

基于GPU并行的二维时空中子动力学MOC程序开发及验证

目前特征线方法（MOC）被广泛应用于反应堆精细中子输运计算。为提高基于MOC方法的时空中子动力学输运计算效率,本文开发了ALPHA程序的动力学计算模块,实现了基于GPU并行的二维精细动力学输运计算。同时,实现了基于GPU并行的CMFD加速计算,并对TWIGL基准题和MINI-CORE基准题进行验证。数值结果显示,基于GPU并行的中子动力学计算方法能保证良好的计算精度,且具有明显的加速效果。     

特征线几何预处理方法比较

网格划分、特征线间距、角度求积组、极角数目和方位角大小等几何预处理过程对特征线法的计算精度和计算效率有较大影响。基于步特征线法开发输运程序,通过数值计算验证所开发程序的正确性并分析两种特征线扫描方法(首尾相间循环扫描法、首尾相接循环扫描法)以及网格划分、特征线间距、角度求积组、极角数目、方位角大小对计算精度的影响。结果表明,开发的程序准确可靠;首尾相间循环扫描方法的收敛速度比首尾相接循环扫描方法慢。     

基于迎风差分格式的TVD聚合物驱数学模拟

聚合物驱替过程中存在饱和度和聚合物质量浓度2个间断,在2个间断之间有"油墙"形成。文中分别运用特征线法(MOC)、一阶迎风差分(SPU)方法和显式全变差递减差分(TVD)方法对聚合物驱替过程进行求解,通过与特征线解进行对比,考察了SPU方法和TVD方法的数值模拟效果。研究表明:SPU方法的精度低,数值耗散严重,对2个间断特别是聚合物质量浓度间断的捕捉能力较差;高阶精度TVD方法分辨力高,但在"油墙"处会产生非物理"振荡"。利用迎风的思想,对传统TVD方法进行了改进。数值实验表明,改进的TVD方法在保持高精确度的同时,还能有效地防止非物理"振荡"的产生,具有较好的稳定性。     

基于51单片机的水温自动控制系统

本系统以8051单片机为控制核心,精密摄氏温度传感器LM35构成前置信号采集电路,过零检测双向可控硅输出光电耦合器MOC3041构成后向控制电路,利用分段PID控制算法,通过调功法对加热系统的水温进行控制,可在40℃到100℃范围内任意设定目标温度,静态误差小于0．2℃。