[en] The results of steam-water and air-water countercurrent flow tests simulating downcomer flow behavior in scaled PWR models are evaluated with respect to various dimensionless scaling parameters. Data at several scales are compared with a correlation based on the Creare 1/15-scale data using a J* variable (which involves the annulus circumference, a characteristic dimension that depends on scale size) and the Kutateladze number (which depends upon surface tension and does not contain a characteristic physical dimension). Data at ¹/₅-scale are better correlated with ¹/₁₅-scale data by the J* parameter scaling, although the amount of data at this scale is very limited. Data at smaller scales, including Creare ¹/₃₀-scale steam-water data reported for the first time, do not confirm either scaling parameter as the correct one, although the results lie closer to the Kutateladze number scaling. Additional large scale tests are needed in order to verify scaling parameters for countercurrent flow at PWR scales