Year
2010
Abstract
The quantity of material unaccounted for (MUF) is generally regarded as important measure of the performance of the facility with respect to the control of the nuclear materials involved. The observed MUF is statistically a random variable that is an estimate of the true MUF because the observed MUF is affected by errors of measurement and the variance of MUF can be calculated by properly combining the effects, which are referred to as the random error and the systematic error on the nuclear material accounting system. The formula proposed by the IAEA technical manual to calculate the variance of MUF and the applicable conditions of the method for a given material balance period has been studied and the derivation of the formula will be described. For an applicable instance, the uncertainty of MUF for the reference pyroprocessing facility (REPF) as a spent fuel treatment process is calculated, where REPF means a model to optimize the safeguardability of a future pyroprocessing facility and the random and systematic error standard deviations of all given measurement systems are assumed as known values. Furthermore, in order to detect a loss of one SQ of Pu with a 95% detection probability and a 5% false alarm probability, the maximum uncertainty of MUF is estimated and is compared to the uncertainty of MUF for REPF.