Perturbation theory for the breeding ratio and for other number ratios pertaining to various reactor processes

Abstract

A perturbation theory formula is derived for use in computing the changes in the frequency ratios of various processes caused by changes (perturbations) affecting any of the reactor parameters. Into this formula are inserted the differences between the values of the parameters, the neutron flux functions and the neutron importance functions with respect to the particular processes being considered. The significance of neutron importance functions is explained in detail and an algorithm is given by which they can be computed. The basis of this algorithm is the algorithm used to compute the ordinary neutron importance function with respect to the asymptotic power by the method of successive approximations.