核设施退役虚拟仿真中烟尘输运过程建模及算法研究

基于三维数值计算可实现核设施退役虚拟仿真中烟尘输运过程仿真，而快速且稳定的数值求解方法是实现动态仿真过程的核心。研究中首先建立相应的数学模型，然后采用半拉格朗日方法对方程进行求解。求解过程中首先对方程采用分裂法，得到各分项方程，然后利用半拉格朗日方法对瞬态项及对流项进行求解，对于不可压缩压力方程采用了基于约束思想的投影算法。研究过程中对立方体空间进行了数值仿真，仿真结果的显示采用OpengGL编程实现，获得了三维流场分布及烟尘浓度分布。该方法能实现模型稳定、快速的求解。     

堆芯中子动力学实时仿真模型

介绍了堆芯中子动力学实时仿真的三种不同模型：点堆模型，三维绝热模型和改进的准稳态模型。并采用了美国Ａｇｏｎｎｅ实验室一维基准问题及秦山６００ＭＷ反应堆弹棒事故对三种模型进行了运算比较。综合计算精度及运算时间表明，随着计算机运算能力的提高，用于堆芯动态仿真，改进的准稳态是国为理想的求解模型。     

板状燃料反应堆热工水力实时仿真程序研究与开发

板状燃料反应堆多通道热工水力实时仿真程序采用三方程模型作为基本模型,补充了适合板状燃料堆芯矩形冷却剂通道的换热系数模型、阻力系数模型等封闭方程,提出了多通道瞬态流量分配模型和堆芯冷却剂通道间流量求解方法,采用查表法求解水和水蒸汽物性参数。IAEA 10MW MTR基准题中反应性引入事故和堆芯失流事故的求解表明,在实时仿真支撑平台SimExec环境下编写与运行的该程序精确而正确。     

SIMULINK环境下求解反应堆动态方程

本文介绍了一种在ＳＩＭＵＬＩＮＫ环境下求解反应堆动态方程的方法，这种方法不需要复杂的编程，借助ＳＩＭＵＬＩＮＫ提供框图输入可以非常简便地建立计算模型，计算时只反应堆态参数填入相应的仿真模块即可，且其计算精度远好于控制系统分析中常用的线性模型。     

压水堆核动力厂控制系统可视化模化与仿真软件——NCS

对压水堆核动力厂控制系统的建模与仿真进行了较系统的研究。提出了用于压水堆核动力厂控制系统快速和精确仿真的被控对象数学模型和数值方法。被控对象模型主要包括堆芯、稳压器、蒸汽发生器、管道及泵的模型等,分别采用了龙格-库塔法和特雷纳方法求解这些模型。设计了面向控制系统结构图的可视化模化平台,实现了图形方式下的控制系统可视化建模,并采用离散相似法对所建立的控制系统数学模型进行求解。研制出了相应的压水堆核动力厂控制系统可视化模化与系统仿真软件——NCS,并用NCS软件对商用核电站控制系统进行了仿真研究,得到了满意的结果。NCS软件对核电站控制系统设计和分析研究工作具有很好的参考和实用价值。     

利用时空分离法建立核电站堆芯实时仿真模型

采用时空分离法实时求解两能群六缓发中子组三维扩散方程.研究了压水堆核电站堆芯系统的仿真建模方法,并考虑慢化剂密度、硼浓度、氙和钐中毒、控制棒位置、燃料和慢化剂温度、燃料燃耗等因素对堆芯中子通量分布的影响.在STAR-90通用图形化仿真支撑平台上,建立了压水堆堆芯的仿真算法与模型,进行了动态特性仿真试验.结果表明,该方法求解实时性好,易于调整.     

可连续移动相边界的直流式蒸汽发生器模型

以全微分公式为数学基础,提出了可连续移动相边界的直流式蒸汽发生器模型。为了改善值求解稳定性,在用状态变量的空间差分来逼近空间导数时,根据不同情况采用前向差分或后向差分。根据该模型编制的程序对ＯＴＳＧ的动态进行仿真,取得了很好的仿真效果。     

时域等效电路法求解耦合腔行波管色散特性的研究

应用时域等效电路法求解耦合腔行波管的色散特性;从行波管耦合腔链的等效电路模型出发,推导了模型的时域电路方程组,采用四阶龙格一库塔法数值求解该方程组,用MATLAB编写了计算程序CTTDCP使用CTTDCP程序计算了某L波段耦合腔行波管的色散特性,求得该管腔通带在1．08—1．48GHz,计算结果与实验结果及电磁仿真模拟结果基本一致,证实了时域等效电路法的正确性和有效性。最后,提出了一种结合等效电路法和电磁仿真模拟优化行波管的管型设计方式。     

压水堆核电站运行堆芯物理过程的PC仿真

阐述了PWR核电站堆芯的模型化问题，建立了适用于微机仿真的核电站的临界堆中子动力学模型，温度效应中子动力学模型和堆芯热传递模型。应用所建模型，建立传递函数，用微机仿真并对仿真结果进行分析。     

一种基于动网格的反应堆控制棒落棒行为分流域耦合仿真方法

本文提出了一种基于动网格的反应堆控制棒落棒行为分流域耦合仿真方法,该方法分别建立了控制棒单棒和驱动杆的二维轴对称模型,保证控制棒和驱动杆对应流域的网格能够根据落棒运动规律自适应地变化。两个流域在每个时间步长内交换流体阻力计算结果,并根据运动方程求解得到的速度来更新控制棒和驱动杆的运动状态,实现分流域耦合。该方法通用性好,计算中考虑了驱动线流道形状的影响,且在计算时间和求解精度之间取得了良好的折中,此外,该方法在计算条件允许的情况下,还能较容易地扩展到三维模型。本文采用该方法对典型反应堆驱动线落棒行为进行了仿真,仿真结果表明,该方法计算结果可信。     

10MW高温气冷堆的集总参数动态模型

应用基本的质量、能量和动量守恒原理，建立了10MW高温气冷堆的动态数学模型。该模型采用了集总参数的建模方法，将反应堆按照不同热工水力学属性划分为多个节块，并采用了具有6组缓发中子的点堆中子动力学公式。对建立的模型进行了动态仿真。结果表明，所建立的模型能够用来进行反应堆的动态特性仿真。     

套管式直流蒸汽发生器动态实时仿真研究

基于基本的流体质量、能量和动量守恒原理,建立了套管式直流蒸汽发生器的动态数学模型。该模型采用集总参数和移动边界的建模方法,将直流蒸汽发生器流道分为欠热段、沸腾段和过热段。采用Gear算法求解,对建立的模型进行稳态和动态仿真,并利用RELAP程序进行校验。结果表明：所建立的模型是正确和有效的,能用来进行直流蒸汽发生器的动态特性实时仿真。     

氢气安全分析软件CYCAS的研发及初步验证

基于计算流体力学方法进行了三维氢气安全分析软件CYCAS的自主研发,采用隐式连续欧拉-任意拉格朗日欧拉方法求解三维、可压、非定常的Navier-Stokes方程组。CYCAS通过求解多组分的质量守恒方程描述多组分气体的扩散和混合,气流中的水蒸气相变行为采用均相平衡模型模拟,而壁面上的相变行为采用Chilton-Colburn相似假设,湍流模拟选用了代数湍流模型和k-ε湍流模型。采用喷射实验HYJET和国际标准测试题ISP23对CYCAS进行了初步验证,计算结果与实验值吻合良好。     

Simulation Research of Magnetic Constriction Effect and Controlling by Axial Magnetic Field of Vacuum Arc

Based on magnetohydrodynamic (MHD) model of vacuum arc, the computer simulation of vacuum arc was carried out in this paper. In the MHD model, mass conservation equation, momentum conservation equations, energy conservation equations, generalized ohm‘s law and Maxwell equation were considered. MHD equations were calculated by numerical method, and the distribution of vacuum arc plasma parameters and current density were obtained. Simulation results showed that the magnetic constriction effect of vacuum arc is primarily caused by the Hall effect. In addition, the inhibition of axial magnetic field (AMF) on constriction of vacuum arc was calculated and analyzed.     

New Non-Equilibrium Thermal-Hydraulic Model,Theory

Corresponding with each non-equilibrium state given by the pressure p, the specific enthalpy of the two-phase mixture h and the void faction α, an equilibrium state defined by p and h is assumed to exist. The relaxation equation for α which relates the non-equilibrium state to the corresponding equilibrium state is derived from the mass and energy equations for the gas phase. The conservation equations for the mixture are spatially differenced in such a way that direct node-node coupling can not take place. Then, the space differencing scheme brings about the three step reduction of the conservation equations, for each of which the physical interpretation is possible. The hydraulic boundary conditions as well as the pump and valve behaviors are incorporated in the model in a natural manner. The model has been implemented in the THYDE-P code to analyze the various dynamic behaviors of the coolant systems.     

Conservative conservation equations: Numerical approach and code-to-code benchmarks

One of the principle features of RELAP5-based system thermal hydraulic codes is the use of a two-fluid, non-equilibrium, non-homogeneous, hydrodynamic model for the transient simulation of the two-phase system behavior. This model includes six governing equations to describe the mass, energy, and momentum of the two fluids. The current version of RELAP-5 is not a fully conservative code because it uses both non-conservative and conservative numerical approximation forms of conservation equations. The current version of RELAP5 versions have mass and energy errors during time advancements, either resulting in (a) automatic reduction of time steps used in the advancement of the equations and increased run times or (b) the growth of unacceptably large errors in the transient results. Therefore, fully conservative conservation equations and closure equations have recently been developed to address this problem. This article demonstrates the numerical approach to implement the developed fully conservative conservation equations into RELAP5 and the results of RELAP5 including developed conservative form of conservation equations. RELAP5 versions including conservative and non-conservative conservation equations are compared for various tests from a single pipe to a whole Pressurized Water Reactor (PWR) model.     

新概念熔盐堆物理计算方法研究及程序设计

考虑新概念熔盐堆燃料盐的流动特性,从基本的粒子守恒方程出发,推导了熔盐堆的中子动力学模型,并采用数值方法对3种工况下熔盐堆的临界问题进行计算,考察流动对有效增殖系数、快中子分布、热中子分布及缓发中子先驱核分布的影响。结果表明：质量流量对有效增殖系数的影响很小,对热中子分布的影响比对快中子分布的影响大,而质量流量越大,缓发中子先驱核移出堆芯的比率也越大。     

A simplified mathematical dynamic model of the HTR-10 high temperature gas-cooled reactor with control system design purposes

A simplified mathematical dynamic model of the HTR-10 high temperature gas-cooled reactor is developed based upon the fundamental conservation of fluid mass, energy and momentum. The model is formulated for coupling reactor neutron kinetics with reactivity feedback and reactor thermal-hydraulics. The reactor is nodalized to employ the lumped parameter modeling methodology, which is mathematically described by differential algebraic equations (DAEs). The developed model is implemented on a personal computer using the MATLAB/Simulink tool. A lot of numerical simulation experiments are investigated and discussed. The transient results show that the model can properly predict the reactor dynamics and can serve as the basis for the model-based control system design.     

Analysis of blowdown experiment of scale steam generator model

A subcooled blowdown experiment in a scale steam generator (SG) model is analyzed by the use of a fluid-structure computer code (MULTIFLEX). The experimental model simulates the secondary side of a SG with a preheater. The MULTIFLEX code that solves simultaneously a coupled set of one-dimensional hydraulic conservation equations and structural dynamic equations is used to analyze the experiment, taking into account the fluid structure interaction between the secondary coolant and the SG structure, the baffle and tube support plates and the divider plate. The computed values of pressure and wall displacement histories agree well with the experimental data. The success of the analysis supports the use of the one-dimensional MULTIFLEX code to analyses of thermal hydraulic transients in the SG secondary side and the validity of the method for modeling the complicated system of the fluid-structure interactions.     

Measurement of Leakage Flow Induced Vibrations of Cylinder

For development of a two-phase flow analysis code by use of two-velocity two-temperature (2V2T) model, six basic equations completely independent and consistent with one another are derived for several possible types of thermodynamical unequilibrium conditions. Characteristic of the basic equations is that evaporation and condensation take place in the saturated water and saturated vapor separately. These phase change equations in the saturated state are rigorously derived using the thermodynamical law.

The energy conservation equation of each phase is derived from the well known total two-phase flow energy equation, using the first law of thermodynamics and conservation equations of mass and momentum of each phase. This derivation method will give assurance that all conservation equations are consistent with one another.

To form simplest 2V2T model, the terms of wall and interphase friction, and heat transfer to the two-phase flow and between phases are considered in this paper.