AIR WATER COUNTERCURRENT-FLOW LIMITATION EXPERIMENTS WITH FULL-SCALE FUEL BUNDLE STRUCTURES

Atmospheric air/water countercurrent flow experiments for fuel bundle top area structures of the pressurized water reactors VVER-440 and VVER-1000 were carried out at different liquid heads above the perforated upper tie plate. Specific attention is given to countercurrent flow limitation across perforated upper tie plates in large channel geometrics. The effects of flow channel size, presence of the unheated fuel rod bundle, and perforated plate thickness on countercurrent flow behavior were observed. The observed nonlinear countercurrent flow behavior in Kg* 1 2 vs. Kf{hook}* 1 2 representation is discussed. © 1990.