Influence on the power peak of different plutonium isotopic compositions in PWR MOX fuel assemblies

Plutonium recycling in PWR's raises the problem of definition of the mixed uranium - plutonium oxide assembly. In order to prevent power peaking at the uranium plutonium assembly interface, neutronic studies indicate that the assemblies should compose several enrichment zones. However, all the feasibility studies performed on PWR plutonium recycling were based on the assumption that homogeneous plutonium fuel would be both identical in all zones of each assembly and identical for all assemblies. It was thus very important to find out whether this homogenization stage was essential to the industrial fabrication process, or, which comes to the same thing, to determine the power peak implications of manufacturing a plutonium assembly in which the different zones correspond to different isotopic compositions. The survey undertaken to assess the extent to which the power peak is influenced by modifications to the isotopic composition is discussed in the present paper. (author). 2 refs, 2 figs, 2 tabs