PREDICTIONS OF REFLOOD HEAT TRANSFER IN A PRESSURIZED WATER REACTOR USING A MODIFIED RELAP 5/MOD2.
A new modified version of the RELAP5/MOD2 computer code for the analysis of reflood phase after a hypothetical large break loss-of-coolant accident was developed. Various rewetting correlations were examined and compared with FLECHT-SEASET reflood experimental data. The RELAP5 prediction of vapor temperatures was low in comparison with the data. The use of a new interfacial heat transfer between droplets/steam resulted in a reasonable prediction of vapor superheats. A revised dispersed flow film boiling correlation which accounts for the enhancement of steam convective cooling by droplet-induced turbulence was incorporated in the code. Comparison of the current results with the data showed significant improvement in the prediction of clad temperature-time histories over previous RELAP5 calculations.
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