Analysis of Inter-channel Cross Flow Effect on PWR LOCA

Predicted in this paper are flow distributions in average and hot channels of the reactor core during small and large break LOCAs. Also estimated based on REALP5/MOD2 calculations are the effects of cross flow between channels on LOCA analysis results. It has been so far generally accepted that a single average channel is sufficient for small break LOCA core hydraulic modelling. However, based on these calculation results, hot channel modeling (two channel modeling) is found necessary in order to guarantee more reliable and conservative results. In large break LOCA blowdown phase, the hot channel thermal hydraulics is worse than that of average channel in both cases with the without consideration of cross flow.