Application of grey model on analyzing the passive natural circulation residual heat removal system of HTR-10

Using the grey correlation analysis,it can be concluded that the reactor pressure vessel wall temperature has the strongest effect on the passive residual heat removal system in HTR (High Temperature gas-cooled Reactor), the chimney height takes the second place,and the influence of inlet air temperature of the chimney is the least.This conclusion is the same as that analyzed by the traditional method.According to the grey model theory,the GM(1,1) and GM(1,3) model are built based on the inlet air temperature of chimney,pressure vessel temperature and the chimney height.Then the effect of three factors on the heat removal power is studied in this paper.The model plays an important role on data prediction,and is a new method for studying the heat removal power.The method can provide a new theoretical analysis to the passive residual heat removal system of HTR.

The development and verification of thermal-hydraulic code on passive residual heat removal system of Chinese advanced PWR

The technology of passive safety is the current trend among safety systems in nuclear power plant. Pas- sive residual heat removal system (PRHRS), a major part of passive safety systems of Chinese advanced PWR, is a novel design with three-fold natural circulation. On the basis of reasonable physics and mathematics models, MI- TAP-PRHRS code was developed to analyze steady and transient characteristics of the PRHRS. The calculation and analysis show that the code simulates steady characteristics of the PRHRS very well, and it is able to simulate tran- sient characteristics of all startup modes of the PRHRS. However, the quantitative description is poor during the ini- tial stages of the transition process when water hammer occurs.

Survey of experiments and code development for the passive residual heat removal system of PWR in China

Three different kinds of experiments and their typical results are surveyed for the passive residual heat removal system (PRHRS) of PWR performed in Nuclear Power Institute of China (NPIC) recent ten years. The typi- cal results of MISAP, a special code for PWR passive residual heat removal system developed and assessed by NPIC, are also described briefly in this paper.

Analysis of the Presence of Vapor in Residual Heat Removal System in Modes 314 Loss-of-Coolant Accident Conditions Using RELAP5

The Westinghouse Nuclear Safety Advisory Letter NSAL-09-8 investigated the possibility of presence of vapor in RHR （residual heat removal） system in modes 3/4 LOCA （loss-of-coolant accident） conditions. This concerns the Westinghouse standard three-loops plant for which the RHR is the low pressure part of the St （safety injection）. In some cases one or both RHR trains may become inoperable for SI function. As a response to this letter, Westinghouse Electric Belgium is providing RELAP5 analyzes for Westinghouse NSSS （nuclear steam supply system） European plants to assess the thermal hydraulic behavior of the RHR suction piping system for ECCS （emergency core cooling system） initiation events postulated to occur during startup/shutdown operations. Several concerns including condensation induced water hammer and voiding at the RHR pump have been investigated. As a conclusion, the analysis allowed to define the bounding hot leg temperature conditions under which both RHR trains remain safely operable. These bounding conditions are then implemented by the customer in their OPs （operating procedures） to achieve safe operations and successful accident management.

Steady characteristic investigation on passive residual heat removal system of Chinese advanced PWR

Thermal-hydraulic characteristic investigation on passive residual heat removal system (PRHRS) of Chinese advanced PWR was conducted to provide input data for PRHRS design and to demonstrate the feasibility of unique design features. A total of 237 sets of test data at steady state have been obtained and the main influence factors on the two-phase natural circulation flow rate and residual heat removal capability were identified. On the basis of theory analysis, a correlation of two-phase natural circulation was obtained, and relative errors of 95% test data were less than ±16%. There is a considerable effect of the system status parameters on the threshold of height between heat source and heat sink, and its correlation of two-phase natural circulation system has been obtained. The steady characteristic research shows that PRHRS has the capability of removing the core decay power through natural circulation.

Calculation Method of Passive Residual Heat Removal Heat Exchanger and Numerical Simulation

The tube inside and outside heat transfer mechanism of Passive Residual Heat Removal Heat Exchanger (PRHR HX) was analyzed. The calculation method of this special heat exchanger under natural convection condition in In-containment Refueling Water Storage Tank (IRWST) was carried out. The single-tube coupling model three-dimensional natural circulation in the IRWST was simulated numerically using Fluent. The heat transfer and flow characteristics of the fluid in IRWST were obtained. The comparison of the results between theoretical arithmetic and numerical simulation showed that the theoretical calculation method is suitable for the heat transfer calculation of PRHR HX.

Experimental study of primary and secondary side coupling natural convection heat transfer characteristics of the passive residual heat removal system in AP1000

Passive residual heat removal heat exchanger(PRHR HX),which is a newly designed equipment in the advanced reactors of AP1000 and CAP1400,plays an important role in critical accidental conditions.The primary and secondary side coupling heat transfer characteristics of the passive residual heat removal system(PRHRS)determine the capacity to remove core decay heat during the accidents.Therefore,it is necessary to investigate the heat transfer characteristics and develop applicable heat transfer formulas for optimized design.In the present paper,an overall scaled-down natural circulation loop of PRHRS in AP1000,which comprises a scaleddown in-containment refueling water storage tank(IRWST)and PRHR HX models and a simulator of the reactor core,is built to simulate the natural circulation process in residual heat removal accidents.A series of experiments are conducted to study thermal-hydraulic behaviors in both sides of the miniaturized PRHR HX which is simulated by 12 symmetric arranged C-shape tubes.For the local PRHR HX heat transfer performance,traditional natural convection correlations for both the horizontal and vertical bundles are compared with the experimental data to validate their applicability for the specific heat transfer condition.Moreover,the revised natural convection heat transfer correlations based on the present experimental data are developed for PRHR HX vertical and lower horizontal bundles.This paper provides essential references for the PRHRS operation and further optimized design.

螺旋半圆管夹套式余热排出装置传热分析及设计程序开发

提出一种适用于小型反应堆的螺旋半圆管夹套式非能动余热排出装置,利用螺旋半圆管夹套具有的传热效率高、结构紧凑等优点,与反应堆主容器形成一体化的紧凑设计。基于此,对螺旋半圆管夹套的传热过程进行了分析,提出传热计算模型并基于此开发了热工设计程序,通过与公开文献中试验数据的对比分析,验证了程序的正确性,可以用于半圆管夹套式余热排出装置的工程设计。

小型堆二次侧非能动余热排出系统特性计算分析

为提高反应堆安全性,基于自然循环的非能动余热排出系统在小型反应堆中有着广泛的应用。本文基于已完成的小型一体化核动力装置中间回路换热实验,用RELAP5(Reactor Excursion and Leak Analysis Program)对中间回路自然循环运行特性开展了计算分析工作。研究发现,载热功率的程序计算结果与实验数据符合良好,可表征系统的自然循环特性。在余热排出系统中,系统回路的压力由蒸汽发生器(Steam Generator,SG)一次侧平均温度所决定,SG一次侧入口温度、质量流量与冷热源高度差对余热排出系统换热性能影响显著。当SG一次侧入口温度较高时,余热排出系统换热性能对系统回路阻力更加敏感,这些结果为进一步研究小型堆非能动系统提供了有价值的应用。

绕丝棒束组件过渡流摩擦阻力实验研究

绕丝棒束组件低流速下摩擦阻力是钠冷快堆堆芯热工水力研究的重点内容之一。通过对现有组件摩擦阻力系数公式应用于过渡流存在的问题、现有组件摩擦阻力实验在低流速时出现的不同摩擦阻力特性的分析讨论,以及对一个37棒组件低流速摩擦阻力的实验研究,提出了组件内流动的转捩特性和提高经验公式在低流速时计算准确性的有效策略。研究结果表明:绕丝棒束组件内流动转捩并不是同时发生,而是在部分子通道的局部先发生,随着流速的增加扩散到整个组件,只有当一定数量子通道都发生转捩时,棒束的平均摩擦阻力才会显著增加。绕丝棒束组件摩擦阻力系数公式应尽可能使用小的层流向过渡流转捩的临界Re和插值指数,使公式尽早开始转捩,并平滑向过渡流过渡。

自硬-微波加热复合硬化硅酸盐粘结剂砂性能研究

针对自硬硅酸盐粘结剂砂用于铸铁件时存在硬化速度慢、对环境湿度敏感、砂型(芯)强度低、溃散性差四个问题,本文选择一种新型硅酸盐粘结剂,以陶瓷砂为原砂,在采用固化剂自硬的基础上,还通过微波加热以及添加粉末促硬剂,进行了复合硬化工艺的研究。首先,研究了微波加热工艺参数对型砂试样性能的影响,确定了优化微波加热工艺:加热功率为900 W、加热时间为180 s;而后,选用了三种粉末促硬剂进行优化,得到的最佳粉末添加剂优化方案为粘结剂2.2%、微硅粉0.2%、氧化铝0.2%、石英粉0.06%。结果表明,该组优化方案相比较不加入粉末添加剂,使砂型(芯)1 h强度提高至1.86 MPa,24 h强度提高至2.17 MPa,98%RH吸湿强度提高至1.45 MPa,800℃残留强度降低至0.75 MPa,其常温强度值和残留强度值分别达到和接近自硬树脂砂的水平。

新型兆瓦级紧凑核动力装置的非能动余热排出系统设计分析

热管堆具有结构简单、布局紧凑、固有安全性高的特点,是无人潜航器的理想堆型之一。针对采用热管堆的新型兆瓦级高效紧凑核动力装置,设计了一种利用自然循环冷却热管绝热段的非能动余热排出系统。使用计算流体力学方法对不同几何参数的余排系统的排热能力进行模拟分析,使其保守满足最大余排功率的需求。结果表明:热管管束周围设计围板导流有利于降低流体最高温度,围板进出口宽度几乎不影响换热能力,而延长围板下部不利于自然循环;3.5兆瓦热管堆的应急冷却舱轴向长度为160 mm时可以保守满足最大余排功率,并在5~25℃的环境温度下均可正常工作。

基于MBSE的铅冷快堆非能动余热排出系统设计需求分析

针对传统的铅冷快堆非能动余热排出系统设计中存在开发效率低、迭代周期长、模型二义性等前期需求问题,本研究将基于模型的系统工程(Model-based System Engineering,MBSE)方法应用于铅冷快堆非能动余热排出系统设计需求中,结合设计流程进行系统架构的初步设计,该系统架构由需求分析、功能分析和设计综合三部分组成。结果表明:需求分析阶段生成的需求图和用例图可捕获系统需求并确定系统顶层用例;功能分析阶段绘制的时序图、活动图和状态机图可形成系统功能模型并提供早期确认与验证;设计综合阶段建立的白盒模型最终实现系统架构的分析与设计。采用该方法设计的系统架构可确保前后设计需求一致性,进一步降低设计风险并提高设计效率,可为数字化铅冷快堆非能动余热排出系统设计与优化提供应用参考。

“华龙一号”余热排出系统氧化运行期间对周边区域的影响分析

余热排出系统的辐射水平在机组停堆过程中会明显变化,氧化运行期间达到停堆峰值,对周边区域产生影响。对“华龙一号”余热排出系统停堆峰值时刻周边区域的辐射水平进行了计算,对比运行电厂实测最大值,综合分析给出了余热排出系统对周边区域辐射水平的影响,同时提出了相应的优化建议。

紧凑式余热排出换热器实验研究

针对核电领域余热排出系统的高效紧凑式换热需求,设计并搭建了基于印刷电路板换热器(printed circuit heat exchanger, PCHE)的余热排出系统流动换热实验平台,对PCHE冷、热侧的流动与换热特性开展了实验研究。研究结果显示,在650 mm×460 mm×60 mm PCHE试验件模块中最大可实现1 336 kW换热。采用修正威尔逊法开展换热特性数据分析,分离出冷侧和热侧对流换热系数。数据分析表明,PCHE整体换热性能与流体流量以及温度密切相关。热侧温度对热侧对流换热系数影响有限。流动特性数据分析显示,PCHE冷、热侧压降随流量上升而增大,热侧由于进出口微针肋的存在,压降显著高于冷侧。基于实验数据拟合了冷、热侧努塞尔数以及摩擦因子计算关联式。其中努塞尔数关联式平均误差为10.44%,冷、热侧摩擦因子关联式误差分别为6.71%和7.13%。研究结果表明PCHE是满足核电领域高效紧凑余热排出需求的有效方案。

一种改进生成对抗网络的遥感图像去云方法

在获取遥感图像的过程中,受天气等因素影响,得到的图像会含有云层,这直接影响了后期对于遥感图像的使用。针对这种问题,基于改进的生成对抗网络,提出了一种遥感图像去云方法。首先,网络的生成器主要结构为深度残差收缩网络,可以更好地去除噪声,并将生成器网络中的批归一化更换为组归一化以提高模型训练效率;其次,在网络损失函数中加入感知损失以进一步提高网络的去云效果。实验结果表明,相较于传统方法和深度学习方法,该方法在薄云处理时峰值信噪比最低提高了0.14 dB,最高提高了9.41 dB,结构相似性最低提高了0.01,最高提高了0.17。在厚云光学遥感图像去云处理方面,PSNR最高可提升6.97 dB,SSIM最高可提升到0.11,在主观视觉效果上也取得了较好的效果,验证了该方法的可行性和良好性能。

AC600 二次侧非能动应急堆芯余热排出系统实验装置及研究计划

ＡＣ６００二次侧非能动应急堆芯余热排出系统实验装置是一座大型非能动安全系统实验研究装置。在设计上，它以热工水力模拟理论及模拟准则为依据，在保持原型系统主要热工水力现象和过程的前提下，对系统进行了必要的简化。本文介绍了该实验装置回路、电气、仪表及测控系统的设计原则和设计结果，以及第一阶段研究计划和内容。最后。

合金渗碳钢件锻造余热等温正火原理研究

研究了常用渗碳钢利用锻造余热正火过程中可能出现的不良显微组织以及它们在重行加热时的粗大晶粒遗传性，阐述了控制停锻后冷却速度和温度使钢件在冷却时不发生相变，而在等温时形成要求的α＋Ｐ组织及硬度的锻热正火工艺原理。

基于流固耦合的余热排出泵转子模态分析

核电用余热排出泵的可靠性至关重要。通过ANSYS的FSI功能对余热排出泵进行流固耦合分析,得到流体对固体的流固耦合作用力;应用ANSYS中的模态分析功能对余热排出泵转子无预应力下的模态以及流固耦合作用力和旋转离心力作用下的模态进行了对比分析。结果表明:流固耦合载荷力对转子固有频率的影响大于旋转离心力;在同时考虑流固耦合力和旋转离心力条件下,余热排出泵转子固有频率介于只考虑旋转离心力和只考虑流固耦合力的固有频率之间,且除第3阶外均小于无预应力下的固有频率。其中,第2阶模态的固有频率与无预应力相比更接近于激振频率。在预应力作用下,振幅有所上升。

基于Kriging模型和遗传算法的泵叶轮两工况水力优化设计

为了拓宽余热排出泵设计高效区的范围,提出了一种基于Kriging近似模型和遗传算法的优化方法。采用拉丁超立方试验设计方法对叶轮叶片的进口冲角?β、包角φ及出口安放角β2进行16组方案设计,并采用ANSYS CFX14.5对16组叶轮方案进行定常数值模拟,选取离心泵设计工况1.0Qd和大流量工况1.62Qd下的效率为水力优化设计目标,建立了效率与叶片三个参数之间的Kriging近似模型,并应用多目标遗传算法对近似模型进行寻优,得到了最优的叶片参数。对原始方案进行外特性试验,数值模拟结果与试验结果基本吻合。优化后,叶轮在两工况下的效率均高于原始泵,效率分别提高了5.53%和2.29%。同时对比优化前后的泵内部速度分布,表明在设计工况和大流量工况下,优化后的叶轮内部相对速度分布更均匀,水力损失较小。提出的叶轮优化方法对泵性能提高提供了有效参考。