The paper presents CFD code validation and benchmarking against the NUPEC BFBT (BWR FullSize Fine-Mesh Bundle Tests) data, performed within the OECD/NRC BFBT void distribution benchmark and as part of the NURESIM (European Platform for Nuclear Reactor Simulations) Integrated Project. Sub-cooled flow boiling occurs in many industrial applications and is characterized by large heat transfer coeff...