Search

The void generation in downcomer during the late reflood phase and its effect on overall transient is evaluated using the post test analyses of the CCTF C2-4 (Run 62) experiment. C2-4 test, which was performed at JAERI, is a reflood test for the typical Westinghouse 4 loop plants. TRAC-M and RELAP 3.2.2γ codes are chosen in this study. Results show that both codes overpredict downcomer water level reduction. To examine the sensitivity of the interfacial drag model in the downcomer region, Blasius model option is selected for TRAC-M for the sensitivity study. Also, Blasius model is implemented in RELAP code. The sensitivity runs using Blasius model show that it enhances the steam venting in the downcomer. With the Blasius interfacial drag model, both codes show a good agreement with the experiment for downcomer level. Fuel cladding temperatures predicted by the codes are still higher than the measured data.