THE EFFECT OF THE TIMESCALE OF THE COSINE SUBCHANNEL CODE BASED ON THE TWO-FLUID MODEL ON THE REFLOOD PHENOMENON SIMULATIONS

Abstract

The COSINE Subchannel code (cosSubc_2f) is a thermal hydraulic analysis program for nuclear power plants. In order to verify the simulation ability of the COSINE subchannel code for reflood phenomenon, this study uses two-fluid model to predict the reflood phenomenon. The distribution of the maximum temperature and wetting time of the axial cladding under different time steps is calculated numerically, and the maximum temperature and wetting time of the axial cladding of the test section are taken as the verification objects, and the relative error of the out-of-synchronous length is studied. The results show that appropriate time step can reduce the prediction error of the maximum temperature and wet time of the envelope, propose the best calculation step range, and find that the calculation results are slightly conservative. Therefore, this procedure can be used for the prediction of reflood phenomena.