小型堆包壳破损状态下利用稳压器去除放射性研究

利用MELCOR程序对小型船用堆稳压器喷雾除气过程及停堆过程进行建模,进而模拟核动力装置从功率运行至降功率除气,以及除气结束后停堆消除稳压器气腔的全部物理过程。通过对反应堆关键运行参数变化趋势的仿真分析,验证了模拟的物理过程的合理性。结合建立的除气及停堆仿真模型,计算分析了包壳破损状态下,稳压器喷雾除气、停堆过程对稳压器内惰性气体含量的影响,评估了稳压器高点放气和喷雾除气对放射性物质的去除作用。研究结果能为小型堆包壳破损状态下放射性安全管理策略提供指导和帮助。     

10 MW高温气冷实验堆硼吸收球停堆系统气力输送模拟试验研究

吸收球停堆系统是10MW高温气冷实验堆(HTR-10)的第二停堆系统,于紧急事故停堆之后、重新开堆之前投入运行,利用负压输送过程将在紧急停堆时进入反应堆堆芯落球孔道内的中子吸收球输送到位于堆顶的贮球罐内,实现正常开堆或反应堆再临界。运用气力输送的密相输送理论,对回路各部件和各管段的气固两相流阻力进行计算,并在1：1模拟试验台架上,以空气和氦气为载体,真实硼吸收球为物料,进行了气力输送试验研究。试验数据与理论分析相符合,吸收球第二停堆系统的气力输送功能满足HTR-10工程的技术要求。     

岷江试验堆低浓化后堆内反应性变化分析

岷江试验堆(MJTR)使用低浓燃料后,堆芯装载发生变化。本文根据低浓化后各种堆芯参数的改变,分析计算了135Xe与149Sm这2种反应堆中最重要裂变产物的变化对堆芯反应性产生的影响,并给出额定工况运行与停堆后2种情况下的反应性变化曲线,使反应堆操纵人员了解毒物反应性的变化规律,以便于在实际运行中应对工况变化,保证反应堆正常安全运行。     

核反应堆冷启动至达到临界状态反应性引入自动控制方法研究

研究了压水堆从冷停堆状态达到临界状态的自动启堆控制方法。参照手动启堆操作过程,设计了2种反应性引入自动控制算法;利用6组缓发中子点堆模型,对控制方法的效果进行了模拟仿真实验验证。结果表明,所设计的算法能够通过适时地控制引入反应性,使反应堆达到临界状态。     

船用堆自动棒动态反应性Simulink仿真模块设计

船用堆运行中功率频繁、剧烈变化需要自动控制棒频繁调节。针对该特点及现有反应堆系统微机仿真程序存在的控制棒反应性描述不合理、不准确的问题,设计了船用堆自动棒动态反应性Simulink仿真模块。该模块作为船用堆物理热工参数快速计算Simulink程序的子模块,应用于船用堆典型动态过程仿真表明：该模块能够模拟动态过程中的自动棒棒位和相应的动态反应性,适用于船用堆物理热工参数快速计算,对船用堆动态过程的仿真和物理热工参数快速计算有重要意义。     

CPY核电厂低温超压保护改进的研究

法国CPY核电厂的双重低温超压保护,即在一回路满水的冷停堆工况下,降低稳压器先导式安全阀的开启/关闭压力整定值,在余热排出系统(RRA)正常运行时由RRA安全阀提供低温超压保护,在RRA因破口或误操作隔离时,则由降低了开启/关闭压力整定值的稳压器安全阀提供低温超压保护。低温超压的瞬态模拟和应力分析的结果显示降低稳压器安全阀的开启/关闭压力整定值能够在低温冷停堆状态下为反应堆冷却剂系统(RCP)提供有效的超压保护,避免反应堆压力容器出现脆性断裂,确保一回路压力边界的结构完整性。     

中国实验快堆主冷却系统建模与仿真研究

中国实验快堆(CEFR)是钠冷快中子反应堆,其一、二回路的运行特性对反应堆的安全运行具有重要的影响。使用JTopmeret软件建立CEFR一、二回路主冷却系统和蒸汽发生器(SG)的仿真模型,用于计算系统任意一点的流量、压力、温度等运行参数。在稳态及瞬态工况下,系统主要参数仿真值与设计值的误差均小于2%,满足系统仿真的精度要求。     

WWER型核电机组反应堆停堆保护系统设计优化与改造

在进行核电机组反应堆停堆保护系统定期试验时,需依次将停堆断路器实体断开,此类定期试验风险较大,国内外运行的核电机组多次发生在反应堆停堆保护系统定期试验过程中由于设备故障导致非计划停堆的事件,造成了较大的经济损失.论文介绍了某WWER核电机组反应堆停堆保护系统设计优化方案及改造的实践成果.     

两环路核电厂反应堆冷却剂系统仿真分析

利用热流体系统仿真分析软件(Flowmaster)建立了两环路核电厂反应堆冷却剂系统(RCP)仿真模型,对功率运行稳态工况、启停堆偏环运行稳态工况、丧失厂外电主泵惰转瞬态工况进行了模拟,得到了RCP在上述工况下的运行特性参数。结果表明,仿真计算与设计值及实际运行值之间的误差小于4%,仿真模型能较好地模拟RCP的运行,为后续同类型电厂的设计优化和运行提供参考。     

水冷聚变堆主回路活化产物源项计算分析

水冷聚变堆中结构材料活化腐蚀产物和冷却剂活化产物是正常运行工况下的最主要放射性来源,也是反应堆运行及维护过程中工作人员辐照剂量的直接来源。本文使用CATE V2.1程序对国际热核聚变实验堆(International Thermonuclear Experimental Reactor,ITER)LIM-OBB(Limiter-Out-Board Baffle)冷却回路的活化腐蚀产物和水活化产物进行模拟计算,并根据CATE模拟得到的放射性活度通过点核积分程序分别计算正常运行1.2 a及停堆15 d的剂量率。计算结果表明,反应堆运行期间冷却剂活化产物比活度和剂量率远大于结构材料活化腐蚀产物,而停堆后冷却剂活化产物迅速衰变完,结构材料的活化腐蚀产物成为比活度和剂量率的主要来源。     

泳池式反应堆自启停控制技术研究

反应堆实现自动启停，可以有效减轻运行人员工作强度，减少误操作，提高反应堆启动运行的安全可靠性。本文基于对典型泳池式反应堆的工艺特点以及启动操作的分析，对泳池式反应堆自启停系统的控制范围、层次结构、断点、典型控制逻辑进行研究，并搭建泳池式反应堆自启停的仿真测试系统。该自启停系统能够实现泳池式反应堆的自动启停，启停过程无人工操作，降低人员误操作可能性。      

Some Aspects of LWR's Water Chemistry

The hypothesis laid down in this paper offers an alternative to the current interpretation of the processes: hideout (hideout-return), crud deposition and change of the coolants activity level in the nuclear power reactors under different operating conditions.

This alternative is based on the supposition that the heat flux has not a direct effect on the processes mentioned above, but acts through the heat transfer mechanism in the boundary, caused by itself.

The boundary influenced by heat flow is in non-equilibrium state and in such system states (at adequate heat flux) non-equilibrium structures called dissipative structures arise which ale closely connected with heat transfer mechanism. The transport and the location of the colloidal corrosion products dispersed in steam generators-or reactor water during the units operation are strongly influenced by the existence of dissipative structures. The transport and location of the main part of ion species depend also on the existence of these structures because the colloidal particles act like collectors of the ions dissolved in the water (The ions are inserted in the colloidal particles double layer).

The hideout and hideout-return phenomena are interpreted as closely connected with the existence of the above mentioned dissipative structures. It was attempted to consider the changes in nuclide concentrations in the LWR coolant upon start-up and shutdown as hideout respectively hideout-return processes. The recent shutdown chemistry aspects are discussed also.     

Analysis of loss of coolant accident in MTR pool type research reactor

In MTR research reactors, heat removal is, safely performed by forced convection during normal operation and by natural convection after reactor shutdown for residual decay heat removal. However, according to the duration time of operation at full power, it may be required to maintain the forced convection, for a certain period of time after the reactor shutdown. This is among the general requirements for the overall safety engineering features of MTR research reactors to ensure a safe residual heat removal. For instance, in safety analysis of research reactors, initiating events that may challenge the safe removal of residual heat must be identified and analyzed.In the present work, it was assumed a total loss of coolant accident in a typical MTR nuclear research reactor with the objective of examining the core behavior and the occurrence of any fuel damage.For this purpose, the IAEA 10 MW benchmark core, which is a representative of medium power pool type MTR research reactors, was chosen herein in order to investigate the evolution of cladding temperature through the use of a best estimate thermalhydraulic system code RELAP5/mod3.2.     

基于THERMIX/BLAST和vPower平台的HTR-PM工程模拟机开发

模块式高温气冷堆示范电站（HTR-PM）在山东荣成石岛湾开始兴建,本文通过将THERMIX/BLAST程序嵌入至vPower仿真平台,开发了HTR-PM工程模拟机。其中两个嵌入vPower仿真平台的THERMIX/BLAST程序模块分别模拟2个由堆芯、一回路和蒸汽发生器组成的蒸汽供应系统模块,与利用vPower仿真平台建立的汽轮发电机系统模块相连接,在平台上实现了数据的管理及人机界面。该工程模拟机可用于模拟和分析HTR-PM的稳态工况、瞬态事故工况。     

兆瓦级空间气冷堆系统启停堆瞬态分析

本文针对兆瓦级高温气冷堆布雷顿循环系统,采用Fortran语言开发系统分析程序TASS,包括堆芯、透平-发电机-压气机、回热器、冷却器和热管式辐射散热器等模型。通过设计值与程序计算值对比对TASS进行验证,并利用TASS对系统启动、停堆瞬态工况进行数值模拟。结果显示,通过分两阶段、阶梯式引入正反应性和提高涡轮机械的转轴速度,堆芯流量和功率匹配良好,系统可在3.5 h内完成启动过程,达到反应堆功率3 406 kW、流量14.2 kg/s的稳态运行。系统停堆过程中,反应堆可依靠自身的非能动余热排出能力,确保芯块和包壳温度与熔点间存在较大安全裕量,实现安全停堆。     

Experimental simulation study on start-up of the 5 MW nuclear heating reactor

An experimental simulation study on the start-up of a low temperature, natural circulation nuclear heating reactor (5 MW developed by the Institute of Nuclear Energy of Tsinghua University, Beijing) is presented. The experiment was performed on the test loop (HRTL-5), which simulates the geometry and system design of the 5 MW reactor. The manifestation of different kinds of two-phase flow instability, namely geysering, flashing instability and low steam quality density wave instability on the start-up are described. The mechanism of flashing instability, which has never been well studied in this field, is especially interpreted. Based on the study of these instabilities, it is suggested that the start-up process, from initial condition to boiling operation condition, should consist of three steps: increasing of initial pressure by means of a noncondensable gas (N₂), start-up of the reactor at this pressurized condition (single-phase regime operation), and transition to a lower pressure, boiling operation. Three transition methods are discussed. As a result of these studies, the method of transition with low heat flux and low inlet subcooling is proposed. A stable start-up process of the 5MW reactor is achieved by careful selection of the thermohydraulic parameters.     

Design of the VVR-S research reactor

A water-cooled, water-moderated reactor for facilitating scientific research endeavors on applications of nuclear energy in peaceful pursuits has been built in the Soviet Union.Such reactors are currently completed and in operation in the Soviet Union and in other Socialist countries. Six such reactors were put into operation during 1957–1959; five reactors (four of which are built to handle power surges) are in the stage of preparation, assembly, and start-up tests.This article describes the design of the VVR-S reactor and its experimental facilities. The physical characteristics of the reactor have been described in an earlier paper [1].     

反应堆核加热冷启动压力控制及超压问题仿真分析

基于反应堆核加热冷启动过程操纵和控制要求，开展了反应堆核加热冷启动过程压力自动控制方法研究，完成了系统压力自动控制方法设计与控制仿真验证；同时对冷启动水密实状态的超压问题进行了仿真分析，提出了防止超压事故的联锁控制方法。结果表明，当核功率不超过一定功率水平时，压力自动控制方法可实现反应堆核加热冷启动过程系统压力的有效控制。      

INET-5MW区域供热模式堆的启动研究(英文)

介绍了INET-5MW反应堆,给出了此堆的热工水力设计参数及主要特性,分析了其启动过程及热工水力不稳定性对此过程的影响。INET-5MW反应堆启动的主要困难是从常压到正常工况要经过不稳定区域。为了避开不稳定性,我们认为启动过程应分为两个阶段。本文给出了三种启动方案的由DACOL程序计算的结果,并进行了对比分析。同时,对每个方案检查了是否可能产生不稳定性。结果表明,这三个方案的启动过程均未发生不稳定现象。因此,可以认为INET-5MW反应堆可以安全稳定地达到运行工况。最后,本文给出了不稳定性对低温核供热堆沸水方式启动影响的几点结论。