The measurement of swirling flow in HIFAR fuel elements and the effects of fitting flowsplitters

Abstract

Measurements have been made of swirl in the coolant flow at the inlet of HIFAR fuel elements before and after flowsplitters were fitted in the inlet nozzles. There was considerable swirl before installation of the flowsplitters, and the amplitudes and directions of the swirl formed a symmetrical pattern over the core. The swirl activity distribution appears to have a definite relationship to positions in which some fuel element damage had been noticed. After flowsplitters were fitted, the swirl velocities were found to have been reduced by a factor of about twenty.