Inverse kinetics reactivity measurements on the materials testing reactor HIFAR.

Abstract

Inverse kinetics method of reactivity determination is compared with the asymptotic doubling time method and found to give more accurate results for the materials testing reactor HIFAR. The differential reactivity worth profile of the HIFAR coarse control arms is measured using the inverse kinetics method and the reactivity worth is found to be proportional to M-º.75±0.10, where M is the mass of fissile material in the reactor. The fuel mass dependence is shown by perturbation theory to be a function of the relative flux depression at the fuel. The temperature coefficient of reactivity is found to be proportional to M-1.01±0.16.