Application of ISO-TAG4 to the Reporting of Limit of Error on the Inventory Difference

A standard reference does not exist for evaluating and expressing systematic and random uncertainty, thus, there is no basis for comparing measurement uncertainties at different facilities. Based on recommendations of the International Committee for Weights and Measures, the National Center for Standards and Certification Information, which is responsible for information on standardization programs and related activities, has published ISO-TAG4, Guide to the Expression of Uncertainty in Measurement (1993). The Guide establishes general rules for evaluating and expressing uncertainty in physical measurements by presenting definitions, basic concepts and examples. It focuses on the methods of evaluating uncertainty components rather than categorizing the components, thus avoiding the ambiguity encountered when categorizing uncertainty components as \"random\" and \"systematic.\" This paper presents an overview of the terms specific to the Guide, including standard and combined standard uncertainty, Type A and Type B evaluation, expanded uncertainty, and coverage factor. It illustrates Type A and Type B evaluation of random and systematic errors in forms relating to nuclear material accountability work. This guide could be adapted by the MC&A community.