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 II - theory

Abstract

Calculations are presented of the 237Np, 235U and 239Pu fundamental mode fission rates in a thorium assembly based on a diffusion theory code with a DB2 leakage term. Three different thorium cross section sets derived from the ABBN set, the UKNDL68 file and the ENDF/B-II file were used in the calculations and the results compared with each other and with experimental results reported previously. The sensitivity of the instantaneous decay constant of the fundamental mode to changes in partial cross sections is investigated.