Advance in research of non-uniform flow in inverted U-tube steam generators under natural circulation condition

For natural circulation, it is shown that parallel flow in the tubes of inverted U-tube team generators can be non-uniform. And reverse flow occurs within some tubes, which can greatly influence the characteristics of natural circulation. Advance in research of non-uniform flow distribution in UTSG under the natural circulation condition is reviewed, including experiment, mechanism analysis, and numerical calculation. According to the analysis on the advantages and disadvantages of those researches, some proposals for the further study are given. (authors)