THERMO-FLUID DYNAMIC RESEARCH ON THE CHARACTERISTICS OF HEAT REMOVAL FROM THE NUCLEAR FUEL RODS NEAR THE SPACER

间隔件附近核燃料棒排热特性的热流体动力学研究

基本信息

批准号：
07455086
负责人：
FUKANO Tohru
金额：
$ 4.8万
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：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07455086/
关键词：
Multi-phase flow Unsteady flow Nuclear Reactor Flow-Boiling Dryout Burnout Spacer Surface Tension

项目摘要

The effects of the geometry of the spacer, which supports the nuclear rods, on the thermo-fluid phenomena near the spacer were investigated by using two different types of the spacers. One is the ring type and the other is the grid type spacers. The special attention was focused on (a) the mechanism to cause the drypatch dormation, (b) the frequency of the drypatch formation and (c) the temperature distribution near the down side of the spacer. The results are summarized as follows.(1) Even if there is a gap between the spacer and the heating tube surface, the coolant water stagnates in between the spacer due to the surface tension force. Therefore it is mainly the drainage that causes the drypatche formation just underneath the spacer in the case of the present experiment where the spacer with the gap is used. Especially in the case of the grid type spacer the gap is not circumferentially uniform, and the surface tension acts in the circumferential direction as well. Then the water is … More kept more tightly within the smallest gap region than the ring type spacer and acts as if it is solid body. And accordingly the drypatch formation is limited in the region just beneath of the narrowest spacer gap region and more frequent in the grid spacer case than the ring type spacer.Although it has been made experimentally clear that the critical heat flux is smaller in the case of the grid type spacer than the ring type spacer, the reason of it is in the midst of a dispute. The result obtained in the present research is the most probable mechanism so far.(2) The temperature distribution shows that (a) the temperature near the bottom side of the spacer becomes lower in the case with the spacer than without the spacer because the thermal boundary layr is disturbed by the growing bubbles within the spacer. The gap space where the bubbles can move freely is limited to the wider gap region in the case of the grid type spacer but is not limited in the case of the ring type spacer. Then the mixing effect on the cooling of the heating rods is stronger in the case of thr ring type spacer than the grid type. This experimental fact also gives a ground That the ring type spacer is superior to the grid type.(3) The present experimental results show that the drainage of the liquid film even in the case of the annular flow is the more reasonable controlling factor to cause the thermally critical situation of the heating rods, i.e., the burnout, rather than the entrainment deposition theory, which is conventionally supposed to be the mechanism to cause the burnout. Less

通过使用两种不同类型的垫片研究了支撑核棒的几何形状对核棒的影响。一种是环类型，另一种是网格类型的垫片。特别注意的是（a）引起drypatch断层的机制，（b）drypatch形成的频率以及（c）隔离器向下侧附近的温度分布。结果总结如下。（1）即使垫片和加热管表面之间存在缝隙，由于表面张力力而导致的冷却液在垫片之间停滞不前。因此，在本实验的情况下，主要是导致垫片下方的drypatche形成的引流，其中使用了带有间隙的垫片。尤其是在网格类型的间隔者的情况下，间隙并非圆周均匀，表面张力也朝着圆周的方向起作用。然后，水是……比环类型垫片更紧密地保持在最小的间隙区域内，并且好像它是坚固的身体。因此，在最狭窄的间隔间缝隙区域以下的区域中，Drypatch地层受到限制，并且在网格间隔案例中比环形型隔离器更频繁地。在本研究中获得的是迄今为止最有问题的机制。（2）温度分布表明，（a）间隔剂在间隔剂的底部附近的温度比没有间隔者的温度较低，因为温度边界层因间隔器内的生长气泡而扭曲。在网格类型的垫片的情况下，气泡可以自由移动的间隙空间仅限于较宽的间隙区域，但在环类型垫片的情况下不受限制。然后，在THR环类型垫片的情况下，混合效果比网格类型更强。这个实验事实还提供了一个理由，即环类垫片优于网格类型。（3）目前的实验结果表明，即使在环形流量的情况下，液体膜的排水也是更合理的控制因子，以引起供暖棒的热临界情况，即耗尽，而不是进入燃烧的燃烧性，而不是燃烧的理论。较少的