Uranium recycle in PWRs

Uranium recycling allows a better use of the natural resources, but the accumulation of some uranium isotopes (232, 234 and 236) in the spent fuel results in neutronic and radioprotection problems: the parasitic absorption of U 234 and U 236 which requires an over enrichment of the fuel; and the activity of the spent fuel to be reenriched due to some daughters of U 232. Moreover, a choice has to be made between two reenrichment strategies: must reprocessed uranium be introduced into the natural uranium cycle, or in a specialized one. The first part of this paper is devoted to a brief analysis of these problems. In the second part, the neutronic characteristics are presented of a PWR core loaded with fuel made from reprocessed uranium. These results are compared to those related to a standard fuel loaded core; they were obtained by means of cell and core calculations. In the discussion, the importance of some phenomena (self shielding, spectral variation) is pointed out