Proliferation resistance features of reprocessed uranium

Abstract

The introduction of reprocessed uranium in fresh LWR fuel as a measure against proliferation has been recently put forward in the non-proliferation discussion. In particular the use of reprocessed uranium implies the presence of 232U radioisotope and this can make more complicated the possible diversion of the fresh fuel as well as the further re-enrichment of the contained uranium. This work attempts to further evaluate a composition of a proliferation resistant UO2 fuel made of a mixture of fresh and reprocessed uranium implying i.a. the presence of 232U and 236U in the fresh fuel. Based on simulation a composition of new UO2 fuel made half with fresh uranium and the other with reprocessed UO2 is proposed. 232U/208Tl emits a high energy -ray of 2.6 MeV enhancing its detectability and any attempt for an undeclared enrichment to a weapon grade using for example centrifugation process could be complicated as the enrichment of 232U will rise faster than that of 235U. Moreover the high energy particles emitted by 232U and 236U might tend to dissociate UF6 molecules, potentially complicating the centrifugation process. Regarding the radiation conditions of the proposed fuel, the calculations have shown that the dose rate at 1 m from a fuel assembly made of the proposed mixture remained in the same order of magnitude with respect to fuel made of non-reprocessed uranium although the dose rate doubled.