Determination of trace metallic impurities in plutonium bearing mixed oxide nuclear fuel using atomic emission spectrometry

Presently AFFF is engaged in fabrication of PFBR MOX fuel with nominal composition of (U_0.79Pu_0.21)O₂ and (U_0.72Pu_0.28)O₂. Chemical characterization of these fuels for trace metallic impurities is one of the pre-requisite for their use inside the reactor as trace metallic elements influence the fuel integrity and neutron economy significantly. B, Cd, Dy, Eu, Gd and Sm have large neutron absorption cross-section; their presence results in loss of neutrons. Refractory elements such as W, Mo, Ta etc. cause creep resistance resulting in clad damage. Low melting elements such as Zn may cause liquid metal embrittlement altering the fuel structure and consequently failure. Presence of alkali and alkaline earth changes the density and reduces the fissile content. Fe, Cr, Ni, Cu and Pb are the indicators for the process pickup and condition (wear/tear) of process equipment. Overall high impurity content leads to fuel dilution and deterioration of chemical and metallurgical properties of fuel