Nucleate boiling within a fuel assembly affected by CRUD

Abstract

Power output of nuclear reactor and heat exchange between fuel assembly and the coolant can be severely affected by the presence of CRUD on the cladding of the fuel assembly. To understand the flow and nucleation boiling processes in the presence of CRUD, a Lattice Boltzmann model for the thermal 3D multiphase flow was developed and implemented in a high-performance multi-GPU-parallel code. The model is applied to procedurally generated CRUD-like structures and the emergence of bubbles due to superheat is investigated. The simulations predict a shorter evaporation time within chimney-like structures as well as the emergence of bubbles at the top layer of the CRUD.