Assessment of RELAP5 3D two phase flow models for MYRRHA secondary cooling system conditions

A numerical model is developed to assess the thermal hydraulic system code RELAP5 3D correlations’ used for two phase flow in MYRRHA secondary circuit conditions. The well known drift flux model is applicable to a wide range of thermal hydraulic problems in nuclear reactors. The selected correlations for the model, based on the 4 equations drift flux model, show better performance at lower pressures due to its approach to interfacial interac tion and it is suitable for a wide range of thermal hydraulic problems in nuclear reactors. All field and constitutive equations were properly selected and derived to get as acceptable with respect to the simplified approach. For the solution methodology, an iterative scheme was chosen with convergence criteria on exit pressure. The results show great compliance with experimental results.