Evaluation of NDA Techniques for Quantification of the Pu Content in MOX Spent Nuclear Fuel by Destructive Analysis

A number of nondestructive analysis (NDA) techniques are being evaluated and developed to characterize spent nuclear fuel (SNF), including its burnup, fissile content, cooling time, and initial enrichment, to verify reactor operator declarations. Oak Ridge National Laboratory and Texas A&M University are jointly investigating measurements of the self-induced uranium and plutonium x-ray fluorescence for quantification of fissile content in SNF. Gamma and beta radiation in the SNF leads to self-induced x-ray fluorescence of the uranium and plutonium atoms. The resulting x-ray spectra can then be measured by an appropriately designed and implemented instrument. During a previous study, measurements and data analysis were performed on spent MOX lead test assembly rods irradiated at the Catawba Nuclear Power Plant. The declared average burnup of these rods is 45 GWd/MT. The fuel rod’s gamma and x-ray spectra were measured using two high-purity germanium detectors (coaxial and planar) for characterization of fission product peak area ratios and uranium and plutonium x-ray fluorescence peak ratios. This paper describes the comparison of the NDA measurement data and MCNPX simulations with the results of destructive analysis performed on the measured sections of the fuel.