Error propagation in reprocessing input volume measurements: A study based on experiment and computer simulations

The measurements performed at the input of the reprocessing plant to determine the nuclear material flow into the process are complex in nature and require many techniques and instruments. The European Nuclear Energy Agency and the Joint Research Center-Ispra have begun to study the uncertainties affecting the measurement of input solution volume. The study includes experiments on a small-scale input accountancy tank, MITA (Mepis Input Tank Analysis), and analysis of the measurements and error propagation by the Monte Carlo Simulation Program for Reprocessing Input Tank (SPRIT). The SPRIT program has been developed for simulating the complete cycle of measurements performed by the operator at the input of the reprocessing plant to determine the nuclear material flow into the process. For a given plant, a given measurement procedure, and a given fuel solution, SPRIT calculates the volume of liquid and the amounts of uranium and plutonium in the solution, as perceived by the measurement system. The differences between these values and the actual values are attributable to the measurement errors, which are simulated by the use of appropriate stochastic functions associated with each error source. By repeating the calculation, a frequency distribution of the measurements can be built, form which the precision and accuracy of the measurement can be determined