Mechanisms of Burnout Generation due to the Instability and the Transient Change of Boiling Two-Phase Flow near a Flow Obstacle simulating a Spacer of a BWR

模拟沸水堆隔板流动障碍附近沸腾两相流的不稳定性和瞬态变化引起的烧毁机理

基本信息

批准号：
12450076
负责人：
FUKANO Tohru
金额：
$ 9.66万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

A cylindrical flow obstruction which simulates a spacer supporting nuclear fuel rods in BWR was installed in the vertical annular channel. Flow patterns, especially the generation of drypatch and burnout, were carefully observed by a high speed video camera. The time variations of temperature on the heating tube surface were simultaneously measured near the spacer at six axially different location under the experimental conditions of transiently changing flow caused by the sudden change in the heart flux, the inlet quality, the mass flow rate. The effect of flow instability on the generation of burnout was also investigated. The results are summarized as follow.(1) In the transient change of flow caused by the sharp increase of heat flux or decrease of mass flow rate, the effect of transition on the generation of burnout is small and the burnout was occurred only when the heating condition, i.e., the heat flux after the change is as large as the burnout heat flux in steady operation. I … More n low flow rate condition j_L=0.1 m/s burnout is triggered by the generation of the drypatch in the location neither in or upstream of the spacer. The burnout dose not generate downstream of the spacer.(2) The quick reduction of heat flux causes the large scale drypatch extending in the spacer and also reached to the point upstream of the spacer. The temperature increase reaches up to 20 K〜30 K.(3)The drastic increase in the inlet quality causes the flow stably change to a new flow condition. On the other hand the drastic decrease in the heat flux causes the generation of burnout near the spacer due to decreasing the passing frequency of the disturbance waves.(4)The change in flow pattern, in which the velocity increases and shear stress increases, is stable. On the other hand if the change causes the decrease in the velocity the burnout occurs even if the heat flux is less than the steady burnout.(5)The general rule found in the present research is that the passing frequency of disturbance waves is the controlling factor to couse the generation of burn out. That is If the interbal of the passing of disturbance wave becomes long the burnout is easy to occur. Less

在垂直环形通道中安装了一个模拟BWR中支撑核燃料杆的隔离杆的圆柱流反对反对。高速摄像机仔细观察到流动模式，尤其是Drypatch和倦怠的产生。在速度不同的位置，在六个轴向不同的位置，在瞬时变化流动的实验条件下，由于心脏通量突然变化，入口质量，质量流量的瞬时变化流动，在轴向上的六个位置上，温度的时间变化是在轴上六个位置的六个位置。还研究了流动不稳定性对倦怠产生的影响。结果总结如下。（1）在由于热通量的急剧增加或质量流量急剧增加引起的流量变化时，过渡对倦怠产生的影响很小，并且仅在加热条件（即，即在稳定运行中变化后的热量与耗散热量一样大时才会发生倦怠。我…更多的低流速条件J_L = 0.1 m/s的倦怠是由drypatch在间隔者的上游或上游的位置产生的。（2）热通量的快速减少导致隔离剂延伸的大规模drypatch延伸，并且还达到了垫片的上游点。温度升高可达到20 K至30K。（3）入口质量的急剧增加会导致流动的变化为新的流动状况。另一方面，热通量的急剧减少会导致隔离波的传递频率降低，导致隔离器附近的倦怠产生。（4）流动模式的变化（速度增加和剪切应力增加）是稳定的。另一方面，如果变化导致速度下降，即使热通量小于稳定的倦怠，也会发生倦怠。（5）本研究中发现的一般规则是，灾害波的传递频率是促使产生烧毁的控制因素。也就是说，如果灾难浪潮的际交往变长，倦怠很容易发生。较少的