Method development for spent nuclear fuel characterization using isotope dilution HPIC-SF-ICP-MS

This PhD dissertation describes the development of an isotope dilution method, using sector field (SF) ICP-MS coupled with high pressure ion chromatography (HPIC), to determine the elemental mass fractions and nuclide specific compositions of U, Pu, Nd and Gd in spent nuclear fuel (SNF). Firstly, a method requiring less than 60 minutes for the separation of the elements of interest using HPIC was developed and validated. Secondly, the SF-ICP-MS data acquisition parameters and different calculation methods for isotope ratios were investigated to obtain the most precise isotope ratios from transient signals. Thirdly, the elemental mass fractions and nuclide specific composition of U, Pu and Nd in a UOx SNF and those of U, Pu, Nd and Gd in a “Gd fuel” were determined by using isotope ratios and isotope dilution HPIC-SF-ICP-MS. Finally, an overall uncertainty budget for isotope dilution HPIC-SF-ICP-MS was derived using the bottom-up approach. The isotope dilution HPIC-SF-ICP-MS method was compared with an existing ISO 17025 SNF characterization method, in which SNF components are isolated using gravitational ion chromatography followed by their analysis using TIMS and alpha spectrometry.