Fast fission ratio measurements in multi-rod clusters.

Abstract

A series of Indo-Australian collaborative experiments to measure 238U/235U fission rate ratios in UO2 rod cluster fuel elements is described. The measurements utilised the well known gross fission product gamma ray counting technique, with calibration by double-fission chamber and 140La fission product y-xay counting techniques. Results are given for fast fission ratios measured over a range of simulated light water coolant densities from zero (air) to one (H2O), the mid ranges being covered by high density expanded polystyrene, in clusters of 7, 19, 37 and 61 14.24 mm diameter U02 rods.