Variance and covariance calculations for nuclear materials accounting using ''PROFF''

To determine the detection sensitivity of a materials accounting system to the loss of Special Nuclear Material (SNM) requires: (1) obtaining a relation for the variance of the materials balance by propagation of the instrument errors for those measured quantities that appear in the materials balance equation and (2) substituting measured values and their error standard deviations into this relation and calculating the variance of the materials balance. We have developed an interactive, menu-driven computer program, called PROFF (for PROcessing and Fuel Facilities), that considerably reduces the effort required to make the variance and covariance calculations needed to determine the detection sensitivity of a materials accounting system. PROFF asks questions of the user to establish the form of each term in the materials balance equation, possible correlations between them, and whether the measured quantities are characterized by an additive or multiplicative error model. Then for each term of the materials balance equation, it presents the user with a menu that is to be completed with values of the SNM concentration, mass (or volume), measurement error standard deviations, and the number of measurements made during the accounting period. On completion of all the data menus, PROFF presents the variance of the materials balance and the square root of this variance, so that the sensitivity of the accounting system can be determined. PROFF is programmed in TURBO-PASCAL for micro-computers using MS-DOS 2.1 (IBM and compatibles)