Analysis on Proliferation Resistance Factor and Fuel Breeding Capability Based on Even Mass Plutonium Isotope Compositions

Abstract

Actinide recycling options of spent nuclear fuel are estimated to have many advantages such as reducing nuclear waste, increasing nuclear fuel utilization and improving proliferation resistance aspect of nuclear fuel. Composition of spent nuclear fuel consists of heavy nuclides and fission products including uranium and plutonium as main actinide. In addition, it is also consist of some minor actinides (MA) which can be recycled to reduce the volume and radioactive intensity of long-lived radioactive waste and in the same time to increase level of proliferation resistance. In general, some MAs can be utilized as useful material such as increasing nuclear fuel production and producing some even mass plutonium such as Pu-238, Pu-240 and Pu-242 as a control material for protected plutonium production. In this paper, identification of even mass plutonium isotopes production for the application of fuel breeding capability and proliferation resistant aspect of isotopic plutonium production was investigated. A large fast breeder reactor (FBR) model is adopted by using 800 days operation for one cycling operation for 4 fuel batches systems for optimization and analyses. The analysis of loading MA materials into the FBR core regions shows the Pu-238 production is increasing significantly as well as additional production of other plutonium isotopes. Isotopic Plutonium production of Pu-238 as main product can be estimated from fuel conversion process of MA in the reactor. This fuel conversion phenomena of Pu-238 can be identified as fertile material for fuel breeding capability, that Pu-238 can be converted to Pu-239 by neutron capture which is similar process also for fuel conversion of Pu-240 to Pu-241 as fissile materials. In addition, isotopic production of Pu-239 from converted Pu-238 as additional fuel which can be added with some quantities of Pu-239 production from converted U-238 for extending reactor operation. Production of Pu-238 in the reactor are used for categorizing some level of protected plutonium productions which can increase isotopic barrier level of plutonium in term of decay heat (DH) as well as Pu-240 as additional even mass contributor.

Void reactivity aspect and fuel conversion potential of heavy water cooled thorium reactor

“…The power density of 140 W/cc is employed, which is considered twice lower than the power density of PWR standard. The 280 W/cc is the power density in fuel pellet that is estimated to be equal to 100 W/cc in the average core power density of PWR type . Various targeted discharged fuel burnups (6 to 50 GWd/t) have been evaluated.…”

“…At the same time, it gives a negative void reactivity coefficient and provides some other advantages such as high burnup and more proliferation resistance compared with fissile plutonium as a basis of uranium–plutonium cycle case. More proliferation resistance and more breeding capability of thorium fuel can be compared with the reactor, which shows plutonium isotopes in plutonium cycle scheme and gives some advantages for fuel breeding capability as well as some plutonium compositions, which obtain more proliferation resistance . The objective of the study is to analyze the design optimization of heavy water cooled breeding reactors using 233 U–Th as fuel based on the safety aspect of void reactivity and fuel conversion condition of the reactor by adopting a nuclear equilibrium state model .…”