Kullanılmış Yakıttan Uranyum ve Plütonyumun Tam Birlikte Geri Kazanıldığı Yakıt Çevriminin Nükleer Silahsızlanma Açısından Değerlendirilmesi

Abstract

Spent nuclear fuel discharged from a typical LWR contains approximately 95 weight percent (w/o) uranium (U) and 0.5-1.0 w/o plutonium (Pu); the remainder consists of a small amount of fission products and minor actinides. Spent fuel could be reprocessed to recover the useful U and Pu in it. The PUREX (Plutonium Uranium Extraction) chemical separation is a widely applied method for spent fuel reprocessing. In the standard PUREX, U and Pu in spent fuel are obtained as pure and separate streams. Recovery of Pu in pure form causes nuclear proliferation concerns. An alternative to the standard PUREX is the complete co-reprocessing, in which U and Pu are separated from fission products and minor actinides and kept together throughout the whole process. In this study, it is aimed to evaluate the closed fuel cycle employing the complete co-processing from the standpoint of nuclear non-proliferation. To this end, the nuclear-proliferation resistance properties of the once-through fuel cycle and the closed fuel cycles with the standard reprocessing and complete co-processing are compared. The resistance of the investigated fuel cycles against nuclear proliferation is discussed in terms of the amount and quality of Pu formed and the radiation barrier of spent fuel on the basis of one GWe-yr electricity production. By the IAEA's definition, “significant quantity” is defined as the approximate amount of nuclear material for which the possibility of manufacturing a nuclear explosive device cannot be excluded. For this reason, assessments on the amount of material that has to be diverted from peaceful purposes to obtain one “significant quantity” of Pu are made. To evaluate the link between behavior of nuclear proliferation resistance properties and fuel burnup, all calculations are carried out for 33000 MWd/tHM, 40000 MWd /tHM and 50000 MWd/tHM burnup values. The MONTEBURNS burnup and depletion code is used in analyses on the amount and quality of nuclear material formed in the fuel cycles under consideration, and the Microshield dose evaluation code is employed for analyses on the radiation barrier of SF. It is indicated from the study that the closed fuel cycle employing the complete co-processing in which obtained product is blended with enriched uranium and re-used as MOX fuel has the highest nuclear proliferation resistance by considering all the resistance parameters discussed. The nuclear proliferation resistance properties of fuel cycles are positively affected by the increase in burnup value.