Francois M. Hemez

Defining a Practical QMU Metric

The Quantification of Margins and Uncertainties (QMU) has been a discussion topic in the Nuclear Weapons Complex for about five years. While most can agree that QMU is a ratio of margin to uncertainty for a given engineering or physics system, many views exist on how to actually implement such a deceptively simple calculation. Nevertheless, DOE managers have expressed a strong desire that QMU will be the decision making tool of the future. Long range planning in both the science and engineering campaigns call for its calculation as part of project deliverables. In light of these demands, a multidisciplinary group has devised a working definition of QMU that 1) allows uncertainty on both the operating region and the performance requirement, 2) is not restrictive to a probabilistic definition of uncertainty, 3) indicates the level of robustness Q has to assumptions made about M and U, 4) is easily communicated to decision makers. This paper presents an introduction and brief review of QMU to date and discusses a working definition that has been devised by engineers at Los Alamos National Laboratory.