海洋条件下自然循环蒸汽发生器U型管内倒流特性研究

当压水堆处于自然循环工况时，蒸汽发生器U型管内可能发生倒流现象，导致一回路流动阻力增大、自然循环流量降低，为反应堆安全运行带来不利影响。基于RELAP5程序建立了海洋条件下的附加力模型及控制体空间坐标求解模型，对蒸汽发生器所有U型管进行建模和节点划分，计算了海洋条件下蒸汽发生器内U型管的倒流临界质量流量及进出口压差，最后分析了3种海洋条件对U型管内流体倒流的影响。结果表明，倾斜条件下有可能会改变倒流现象；而在航行过程中可能遇到的起伏条件都无法改变倒流现象；当摇摆条件比较剧烈时有可能改变倒流现象。 

Research on Characteristics of U-tube Backflow in Natural Circulation Steam Generator under Ocean Conditions

When the pressurized water reactor is in natural circulation, reverse flow may occur in the U-tube of the steam generator, which will increase the flow resistance of the primary circuit and decrease the flow of natural circulation, which will adversely affect the safe operation of the reactor. Based on the RELAP5 program, the additional force model under ocean conditions and the spatial coordinate solution model of the control body are established, all U-tubes of the steam generator are modeled and node division are conducted, and the steam generator under ocean conditions (inclination, undulation, swing) is calculated. The critical mass flow rate of the reverse flow and the pressure difference between the inlet and outlet of the inner U-shaped pipe are analyzed. Finally, the influence of three ocean conditions on the reverse flow of the fluid in the U-shaped pipe is analyzed. The results show that the backflow phenomenon may be changed under inclined conditions; the undulating conditions that may be encountered during navigation cannot change the backflow phenomenon; the backflow phenomenon may be changed when the sway conditions are severe.