Studies of Advanced Intermediate Heat Exchanger to replace 2^<nd> Na Loop of FBR

本课题的目的是为环式快堆先进中间换热器寻找合适的中间换热介质。我们之前已经开始了对液态金属镓的研究，并拥有了实验装置，所以主要目的是比较铅铋合金作为中间换热流体与液态金属镓的比较。那里的水蒸气条件比轻水反应堆高得多，不能排除钠水反应。本研究旨在引入不与水或钠反应的第三种介质，并将中间换热器与SG相结合，以缩小装置规模。2000年，对实验设备进行了改造，使用了铅铋…更像是一种工作液，而不是镓。随着流体的改变，工作温度从100摄氏度大幅上升到300摄氏度，因此在铅铋和水的循环之间插入了第三个有机冷却剂循环。对铅铋进行了自然对流换热实验，发现铅铋比镓更容易通过自然对流循环，因为铅的体积膨胀系数较大。2001年，通过增加电磁泵进行强制对流实验。铅铋在材料表面的润湿性非常不稳定，这会导致电磁流量计指示不稳定等问题。由此，提出了利用温度脉动的互相关法进行流速测量的新方法。铅铋流体的换热系数低于镓，符合Sabottines经验公式。2002年，铅铋流体进行了气举强制循环实验。气升法是在水循环中建立的，但在液态金属中几乎没有。铅铋和镓都是用氩气循环的。研究了ONITY、Six和Ten的气升特性，并进行了对比研究。结果表明，在低流速区，经验公式与实验结果吻合较好，但当滑移率接近3时，循环性质趋于饱和。综上所述，揭示了镓和铅铋液态金属流体的特点，揭示了许多认识。这些结果可能有助于以重金属液体为工质的演示反应器的概念设计。较少

The purpose of the present project was to find out appropriate materials which could be used as an intermediate heat exchange medium in the Advanced Intermediate Heat Exchanger for loop type Fast Breeder Reactor. We had initiated studies on liquid metal gallium previously and had the experimental apparatus, so the main object was to see how the lead-bismuth alloy was suitable for intermediate heat transfer fluid in comparison with liquid metal gallium.The secondary sodium loop in the FBR transfers the heat energy to the steam generator from the primary sodium to generate steam and electricity. The steam condition there of 24MPa is much higher than that in the light water reactors and sodium water reaction could not be excluded. The present study intends to introduce the third medium which does not react with water nor sodium and combine the intermediate heat exchanger(IHX) with SG to reduce the plant size too.In 2000, the experimental equipments were modified so as to use lead-bismuth … More as a working fluid instead of gallium. With this fluid change the working temperature rose very much from 100 degree C to 300C, so the third cooling loop of an organic coolant was inserted between the loops of lead-bismuth and water. The heat transfer experiment at natural convection was carried out and found that the lead-bismuth could he circulated by natural convection easer than gallium owing to larger volume expansion coefficient.In 2001, the forced convection experiment was performed with adding an electro-magnetic pump. Lead-bismuth has a problem of very instable wettability on a material surface, and this causes problems such as instable indication of the electro-magneto flow meter. Thus, new method of flow velocity measurement from cross correlation in the temperature fluctuation was developed. The heat transfer coefficient was found to be lower than that in gallium and found to agree well with the Sabottines empirical equation.In 2002, the lead-bismuth fluid was tested by the air-lift forced circulation. The air lift method was established in water circulations but scarcely no in the liquid metals. Argon gas was used to circulate the lead-bismuth as well as gallium. The air lift characteristics were studied over fluid density from onity, six and ten, and were studied in comparison. The result showed that the empirical formula agreed with the experimental results over the low flow rate region but circulation property saturated as the slip ratio approached three.As a summary; characteristics of liquid metal fluid of gallium and lead-bismuth were clarified and many knowledge were revealed. These results could contribute to the conceptual design of the demo reactor which uses heavy liquid metals as working fluid. Less