Conceptual Design Study of Fusion Fission Hybrid Reactor
Muhammad Tariq Siddique
Graduate Office, Kyung Hee Univeristy
Professor Myung-Hyun KIM
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The idea of fusion-fission hybrid reactor is very attractive solution of waste burning with evolution of fusion energy. In this study concept of clean nuclear power plant is proposed. The main research objective of the clean nuclear power plant is to burn all high level waste, include transuranic (TRU) isotopes and fission products (FP), in a fusion-fission hybrid reactor. Fusion based TRU burner reactor (FTBR) is proposed which based on a low power tokamak (100 MW max) and annular ring shaped TRU core with metal fuel (TRU 60 w/o, Zr 40 w/o) and FP zone. The TRU and FP compositions are taken as the 1000 MWe PWR spent fuel with 10 years decay. Calculations were performed using MCNPX 2.6 with BURN card. The burn cycle is chosen to be 1100 days (3 years). The power level of TRU core is set to be 2000 MW and to maintain the fission power level the fusion power has to vary with the drop of subcritical level. TBR value more than 1.1 represents self-sufficiency of fusion source fuel. TRU and FP depletion was analyzed by calculating the mass burned per full power year (fpy) (kg/fpy), support ratio and percentage of mass burned per fpy. The toxicity analysis of TRU and FP is also performed by calculating the percentage reduction in toxicity of TRU and FP over the burn cycle. In the end TRU transmutation performance was compared with existing hybrid reactor design. This study is concluded with three major designs of hybrid reactor for waste transmutation (Hyb-WT). First design utilize small tokamak geometry (KSTAR) with a pin type core design and observe to give better TRU transmutation but unsatisfactory FP transmutation. In second design larger hypothetical tokamak geometry is implemented which resulted in improved FP transmutation with a little expense of TRU transmutation performance. Design improvement techniques are applied by different coolant material testing study and reflector optimization study. Hyb-WT with multi material option is observed to be the most optimized design. Third Hyb-WT design is the testing of a novel tube-in-duct core design in place of conventional pin type core design. Hyb-WT with TID core design resulted in best TRU and FP transmutation performance and significant reduction in fusion source neutron utility because of its geometrical advantages. Hybrid test blanket module study is the future extension of Hyb-WT study. Blanket design will be modified and converted to multiple modules instead of single annular core design. A fusion fission hybrid test blanket module (HTBM) is designed which is presumed to be tested in ITER like fusion source environment. In this preliminary design of HTBM the neutron source and loss factors are computed for the detailed neutronic performance analysis. The neutronic analysis of hybrid blanket module is performed for five different TRU fuel types; TRU-Zr, TRU-Mo, TRU-Oxide, TRU-Carbide and TRU-Nitride. TRU in this module is designed to be burned and transmuted from high-level radioactive waste in PWR used fuels. The effect of TiC reflector on transmutation and tritium breeding performance of HTBM is also quantified. MCNPX is used for neutronic computations. Neutron spectrum, capture to fission ratio and waste transmutation ratio of each fuel type are compared to evaluate their waste transmutation performance. Tritium breeding ratio is also compared for two coolant options: Li and LiPb eutectic.