Spacer to suppress departure from nucleate boiling

摘要

In a nuclear fuel bundle for a boiling water nuclear reactor having ferrule spacers, the ferrule spacer closest to the lower tie plate is provided with large apertures. These large apertures constitute the removal of almost all of the material of the ferrule spacer from around the fuel rods consistent with structural requirements. In this lowest ferrule spacer location, it has been found that these apertures within the individual ferrules suppress the tendency of the fuel rods downstream of the first spacer to be subject to departure from nucleate boiling.