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Research on the characteristics of thermal hydraulics in Reduced-Moderation Natural Circulation BWR during startup stage

减慢自然循环沸水堆启动阶段热工水力特性研究

基本信息

批准号：
14380234
负责人：
ARITOMI Masanori
金额：
$ 9.6万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14380234/
关键词：
Reduced-Moderation Natural Circulation BWR Geysering Density wave oscillation Doppler effect Wire-Mesh Tomography SBWR Particle-fluid model Boiling two phase flow 低減速自然循環沸騰水型

项目摘要

With an aim of clarifying the thermal hydraulic characteristics in the reduced-moderation natural circulation BWR during start-up stage, fundamental experiments with regard to thermal hydraulic instability has been experimentally and analytically investigated with a natural circulation parallel boiling channels, which simulates the fundamental and representative flow characteristics around the core. The new findings are as follows.(1)Some thermal hydraulic instabilities that might be occur during the start-up stage due to rapid condensation of steam bubbles or flashing phenomena, such as geysering phenomena and density wave oscillation, have been experimentally investigated under several input thermal conditions and the loop geometries.(2)Bubble size is one of the important factors to determine the flow characteristics. A bubble generator is implemented to change the bubble size. Using bubble generator newly developed by this study, the results confirmed that the bubble generator could … More control the bubbles size. In order to clarify the effect of bubble size on flow structures, measurements of bubbly flow in vertical pipe were performed using ultrasonic Doppler method(UDM), wire mesh tomography(WMT) and digital image processing(DIP). Combination of the three techniques could clarify not only liquid information, but also bubbles' information.(3)We developed measurement system to sent and received pulse ultrasound and developed the software to process received echo signal. And these systems are applied to pattern recognition of the flow pattern from bubbly flow to annular flow.(4)Multidimensional flow analysis code based on the particle-fluid model applied to the experimental results of measured development of bubbly flow in vertical rectangular tube and vertical circular tube. And physical phenomenon to influence a bubbly flow was investigated.(5)Based on the mentioned above results of study, we suggested stability and rational start-up procedure as well as about the necessity of chimney divide. Less

为了弄清减温和自然循环沸水堆启动阶段的热水力特性，利用自然循环平行沸腾通道，模拟堆芯周围的基本和代表性流动特性，对沸水堆热水力不稳定性进行了基础实验和分析研究。新的发现如下。(1)在几种输入热条件和回路几何形状下，实验研究了在启动阶段由于蒸汽气泡的快速凝结或闪蒸现象（如间歇泉现象和密度波振荡）可能发生的一些热水力不稳定性。(2)气泡大小是决定流动特性的重要因素之一。实现了一个气泡生成器来更改气泡大小。利用本研究新研制的气泡发生器，实验结果表明，该气泡发生器能够更好地控制气泡的大小。为了明确气泡大小对流动结构的影响，采用超声多普勒法（UDM）、钢丝网层析成像（WMT）和数字图像处理（DIP）对垂直管道中的气泡流动进行了测量。三种技术的结合不仅可以澄清液体信息，还可以澄清气泡信息。(3)研制了脉冲超声收发测量系统，开发了接收回波信号处理软件。并将该系统应用于气泡流到环形流的流型识别中。(4)将基于颗粒-流体模型的多维流动分析代码应用于垂直矩形管和垂直圆管中气泡流动发展的实测实验结果。研究了影响气泡流动的物理现象。(5)根据上述研究结果，提出了稳定合理的启动程序，并提出了烟囱分隔的必要性。少