Counter Current Flow Limitation Prediction Using CFD

Abstract

Counter Current Flow-Limiting (CCFL) phenomena can occur during the re-flood stage of a Boiling Water Reactor (BWR) core after a loss-of-coolant accident (LOCA). Spray nozzles above the core inject water onto the upper tie plate region. Steam rising through the core due to the flashing of any liquid in the regions below the core or penetrating from above impedes the downward flow of the spray liquid into the core. Computational Fluid Dynamics (CFD) was used to investigate the CCFL phenomenon. Results for different air flow rates were compared with available test data and with traditional correlations. Good agreement between CFD predictions and the test results was achieved.