Physical and economical aspects of Pu multiple recycling on the basis of REMIX reprocessing technology in thermal reactors - 5201

The basic strategy of Russian Nuclear Energy is the closure of fuel cycle on the base of fast breeder and thermal reactors, as well as the solution of spent nuclear fuel accumulation and resources problems. 3 variants of multiple Pu and U recycling in VVER reactors on the basis of REMIX reprocessing technology are considered in the given work. The first 2 variants differ with feeding fissile material. The first variant is the standard REMIX fuel while the second is close to MOX fuel where regenerated uranium is used instead of depleted uranium and the feeding fissile material is reactor grade plutonium. The third variant is an heterogeneous composition of enriched uranium and MOX fuel pins in the fuel assembly. The REMIX fuel is fabricated from non-separated mixture of uranium and plutonium obtained during NPP spent fuel reprocessing with further makeup by enriched natural U or reactor grade Pu. It makes possible to recycle several times the total amount of Pu obtained from spent fuel. The main difference in Pu recycling is the concept of 100% or partial fuel loading of the core. It should be noted that all fuel assemblies with Pu require the involvement of expensive technologies during manufacturing. These 3 variants of the full core loadings can be balanced on zero Pu accumulation in the cycle. The better results in natural uranium savings can be achieved for the standard REMIX(UOX) approach. The use of REMIX technology in the closed fuel cycle appears to be more expensive than the open fuel cycle with direct spent fuel disposal. The Pu positioning in expensive MOX fuel assemblies gives better results from the economical point of view but it is worse for multiple recycling. It is important to note that the uranium multiple recycling in the REMIX fuel form or using the re-enrichment process leads to the uranium isotope composition degradation