CFD analysis of coolant channel geometries for a tightly packed fuel rods assembly at subcritical pressure

•Three coolant channel geometries are proposed for high breeding LWRs.•Thermal hydraulic performance of coolant channel geometries are analyzed.•Design ranges of PWRs and BWRs with proposed geometries are designated.•One type of geometry (Geometry B) is proved to be superior to the others.

This paper analyzes the thermal hydraulic performance of channels with different cross sectional geometries, which were adopted by tightly packed fuel rods assembly for high breeding at operating pressure of PWR and BWR. The calculations were carried out to assess the geometrical effect of coolant channels on thermal-hydraulic parameters by using a CFD code STAR-CCM+. It is found that one type of channel geometry (geometry B) is superior to others because of broad design area of power, cladding temperature and pressure drop.