Resolution of shipper-receiver differences

This report describes statistical procedures for resolving significant shipper-receiver differences (SRDs) for nuclear material transfers and calculating the best estimate of the true amount of special nuclear material transferred. The resolution of an SRD should generally be accomplished by identifying and removing its causes. Physical and statistical methods and logical stepwise procedures for investigating an SRD under various circumstances are recommended in this report. It is concluded that the best estimates of the true quantities of special nuclear material in a transaction are obtained by calculating the inverse variance-weighted values of the net weights, element fractions, and isotope fractions using the measurement results from the shipper, receiver, and referee laboratory, if any, that are accepted as the best available data.