Automated Material Accounting Statistics System at Rockwell Hanford Operations

The Automated Material Accounting Statistics System (AMASS) was developed under the sponsorship of the U.S. Nuclear Regulatory Commission. The AMASS was developed when it was realized that classical methods of error propagation, based only on measured quantities, did not properly control false alarm rate and that errors other than measurement errors affect inventory differences. The classical assumptions that (1) the mean value of the inventory difference (ID) for a particular nuclear material processing facility is zero, and (2) the variance of the inventory difference is due only to errors in measured quantities are overly simplistic. The AMASS provides a valuable statistical tool for estimating the true mean value and variance of the ID data produced by a particular material balance area. In addition it provides statistical methods of testing both individual and cumulative sums of IDs, taking into account the estimated mean value and total observed variance of the ID.