This publication documents the results of an IAEA coordinated research project (CRP)on the application of computational fluid dynamics (CFD) codes for nuclear power plant design. The main objective was to benchmark CFD codes, model options and methods against CFD experimental data under single phase flow conditions. This publication summarizes the current capabilities and applications of CFD codes, and their present qualification level, with respect to nuclear power plant design requirements. It is not intended to be comprehensive, focusing instead on international experience in the practical application of these tools in designing nuclear power plant components and systems. The guidance in this publication is based on inputs provided by international nuclear industry experts directly involved in nuclear power plant design issues, CFD applications, and in related experimentation and validation highlighted during the CRP.