Development of the burnup measurement for fast reactor fuels evaluation of an isotope dilution mass-spectrometry by the Nd-heavy elements method

The applicability of isotope dilution mass-spectrometry to the burnup determination of mixed oxide fuel was investigated. In this study, Nd-148 was employed as the burnup monitor. The method of analysis is briefly presented in the first part. The specifications of the mass-spectrometer used for the study are shown. U-233, Pu-242, and Nd-150 were used as the spike isotopes. The isotopic content and the concentration of mixed spike solution are presented in a table. The formulas for determining the numbers of Nd-148, uranium, and plutonium atoms are explained in the second part. The results of burnup measurement are presented and discussed in the third part. The analytical errors in the determination of atomic densities were 0.4 to 0.5% for Pu and U, and 1.0% for Nd, respectively. The error of the burnup estimation largely depends on the preciseness of fractional fission yield of Nd-148. The measured burnup was also compared with the corresponding values obtained from Cs-137 and Ce-144 as the burnup monitors. (Aoki, K.)