Iaea-sm-367/8/06/p Estimation of Gross Systematic Multiplicative Biases in Reprocessing Plant In-process Tanks

The presence of gross, possibly time varying, systematic multiplicative biases in process tanks affects the estimation of the physical inventory of a chemical separation and concentration facility. This in turn affects the nuclear materials account, especially the near-real time account. The proposed implementation of solution monitoring [1-3] on chemical separation areas will provide appropriate data to enable the estimation of these biases. Central to this will be the in-tank volume measurements that will be recorded at relatively high frequencies and analysed to estimate the transfers into and out of each tank. If the tank measurements are biased, then this will bias these estimates and hence the model of how nuclear material is progressing through the plant. If only one tank is biased, its effect will be fairly transparent so that the bias can be isolated and estimated in a straightforward manner; if not, estimation is more complicated.