[en] A safety analysis code, named as SPACE, for a pressurized water reactor is under development to obtain licensing to be used for the PWR design and to hold entire proprietary rights. The task of KAERI is to develop the physical models and correlations which are required to solve the field equations. It can be divided into four parts; i) flow regime determination, ii) wall heat transfer, iii) wall and interfacial friction, iv) interfacial heat and mass transfer. This paper will describe the process to develop the models for the interfacial area and heat transfer models and correlations which are used for the SPACE code