Assessment of RELAP5/MOD3.2.2γ against flooding database in horizontal-to-inclined pipes

A total of 356 experimental data for the onset of flooding are compiled for the data bank and used for the assessment of RELAP5/MOD3.2.2γ predictions of counter-current flow limitation (CCFL) in horizontal-to-inclined pipes simulating a PWR hot leg. RELAP5 calculations show that higher gas flow rates are required to initiate the flooding compared with the experimental data if the L/D is as low as that of the hot legs of typical PWRs. Based on the present data bank, the new CCFL correlation is derived, which shows the L/D effect. The present correlation agrees well with the database within the prediction error, 8.7% and it is implemented into the RELAP5 and validated against the data bank. The predictions of the flooding limit by the modified version lie well on the applied CCFL curve if the L/D is lower than 22, which is the case of the hot legs of typical PWRs.