Performance Analysis Of BN-600 Fast Reactor For Minor Actinide Transmutation Using Monte Carlo Method

During the operation of a nuclear power plant,some successive capture reactions lead to the formation of transuranics(TRU).These are isotopes which are larger than uranium,which mainly include Plutonium,Americium,Neptunium,and Curium.All these actinides are radioactive with very long half-lives,so disposing the nuclear waste underground containing such radiotoxic isotopes would incur high costs and safety issues.Therefore,removal of minor actinides(Am,Np,Cm)from spent fuel in order to decrease the overall radiotoxicity of spent fuel is a subject of research.In this thesis the idea explored will be that of transmutation of minor actinides.Transmutation refers to breaking down of minor actinides to smaller,less radiotoxic isotopes by way of fission.This can be done by placing those actinides in a fast reactor,or accelerator driven system(ADS),or theoretically any other arrangement providing the neutron flux required for fissioning of actinides.In this thesis,a particular fast reactor is selected(BN-600)for the study of this phenomenon.Calculations are performed using Monte Carlo methods with the codes RMC and MCNP and the results are compared with a benchmark study.The benchmark study was performed by IAEA in two phases.The first phase calculations were performed with weapons grade plutonium.Effective multiplication factor,power and flux distributions were calculated for that reactor model.The results showed up to 80%of the reactor power concentrated in the low and high enrichment zones of the core,which is consistent with the benchmark study.Burn up calculations were also performed on the same core which showed a decreasing keff as a function of burn up.In the next phase,spent LWR fuel was loaded in the reactor with 26%-30%TRU content.To maintain consistency with the benchmark calculations,burn up calculation was performed in a single step over a 140 days.The results showed that Am and Np isotopes were effectively transmuted while Cm and Pu isotopes accumulated.