Time dependent 237Np, 235U and 239Pu fission rates in a thorium assembly during the interval 0 to 200 ns using a pulsed 9Be(d,n) source part I - experiment

Abstract

This paper describes a series of integral pulsed neutron experiments performed in a 0.4 x 0.4 x 0.4 m3 metallic thorium assembly in such a way as to allow direct comparison of space independent reaction rates with calculated reaction rates derived from a code which uses the asymptotic reactor theory approximation to describe leakage. The technique relies on the Fourier decomposition of measured space-time dependent reaction rates and the extraction from these of the reaction rate corresponding to the fundamental three-dimensional Fourier spatial mode. The reaction rates measured were the fission rates of 235U, 239Pu and 237Np following a short (~ 10 ns) burst of neutrons with a mean energy of ~ 2.7 MeV.