Fissile worth of MOX fuel: A non destructive study

Quality of (U,Pu)O2 mixed oxide (MOX) fuels for fast reactor is judged by its fissile worth; quantified as Pu239 equivalence which is governed by the isotopic composition of PuO2 used for fuel fabrication and the concentration of PuO2. An experimental method for directly estimating Pu239 equivalence of MOX fuel pins for the upcoming Prototype Fast Breeder Reactor (PFBR) was attempted using passive gamma scanning (PGS) in this work. A combination method of theoretical and experimental estimations was used to study the dependence of deterioration in fissile worth of stored fuel pins with corresponding change in their PGS responses. This is a novel and effective method to estimate the updated value of fissile worth at the time of reactor loading after long duration of storage after fabrication of fuel pins.