THEORETICAL CALCULATION OF NEUTRON AGE.

This report describes a method for computation of neutron age to the indium resonance in arbitrary mixtures of nuclides. Ages of fission neutrons in a wide variety of modulators were calculated. The method is the Fourier transformed moments solution of the Boltzmann equation, evaluated with multigroup techniques. Initially, the evaluation was for 68 groups however, the number of groups was systematically reduced until an eleven group set was selected as a reasonable compromise between accuracy and ease of computation. The program not only computes group ages, but also provides a slowing down spectrum of average group fluxes per unit lethargy versus lethargy. Combined with a cross section averaging subroutine, this code could provide all required fast constants for a few group reactor physics problem. The final code will handle any number of groups up to twenty. Input data for any one problem is minimal, the main portion of the input consists of a punched card cross section library. It is an economic, simple to execute, versatile code, which meets the engineering accuracy criteria initially postulated. Author