Self-Multiplication Correction Factors for Neutron Coincidence Counting

We have developed self-multiplication correction factors for the nondestructive assay of plutonium oxide or metal in thermal or fast neutron coincidence counters. One correction consists of a series of curves for oxide derived from a Monte Carlo simulation of coincidence counting. Another correction is an approximate, geometry-independent formula which is applicable to any wellcharacterized material. Both correction factors are compared with measurements.