Incorporation of measurement data from irradiated fuel samples into the MTG system at FCF

The Mass Tracking (MTG) System for the Fuel Conditioning Facility (FCF) initially uses calculated values for the mass flows of irradiated EBR-II driver fuel to be processed in the electrorefiner. Validation of the methodology used to calculate these mass values was based on comparisons with measured values obtained on lead experimental subassemblies. Nevertheless, these calculated values are continually verified by measurements performed by the Analytical Laboratory on samples from the element chopper retained for each chopper batch. When the measured data become available, it is necessary to determine if the measured and calculated data are consistent. If so, the MTG System retains the ''best'' data, i.e., the data with the smallest uncertainties. If measured and calculated data are not consistent, measurements must be repeated on a backup sample, after which, again the ''best'' data are used by the MTG System. Knowledge of the uncertainties in both the measured and calculated data is fundamental both to determining whether the data are consistent and to determining which of the data are to be used. The present study uses the availability of a ''large'' number of measured data from the initial chopper batch to estimate uncertainties in the measured and calculated values. Then the analyses of 65 chopper samples from the first 9 batches are used to estimate the biases and trends in calculated-to-measured values of the important data (fissile masses, heavy metal masses and burnup) and recommends a procedure for incorporating the measured data into the MTG system