An estimate of the errors of a method for determining the depletion of spent mixed uranium-plutonium fuel of fast reactors

The indeterminacy in the yield of fission products of plutonium isotopes makes the main contribution to the total measurement error of depletion. Therefore the error increases as the fraction of plutonium, especially its heavy isotopes, in the original fuel increases. The contribution of the random component to the total error is inappreciable, and there is no need to carry out a large number of parallel measurements. It is advisable to make two measurements to eliminate the coarse error. The depletion can be determined with an error no worse than 5% when the total145Nd and146Nd content is selected as the depletion monitor, depending on the composition of the mixed uranium-plutonium fuel.