Reactivity, Isotopic, and Thermal Steady-State Analysis of Homogeneous Thoria-Urania Fuel
- Idaho National Engineering and Environmental Laboratory (United States)
Recent investigations into the performance and economics of mixed thoria-urania fuel cycles demonstrate potential advantages at high burnup. Initial neutronic and fuel behavior calculations for several ThO{sub 2}-UO{sub 2} mixtures being considered for use in commercial nuclear power plants are described.The Monte Carlo N-Particle -Origen2 Coupled Utility Program (MOCUP) was used to analyze the reactivity characteristics and isotopic concentrations of unit fuel pins/cells and lattice/assembly models as a function of burnup and reactivity. Neutronic results for a three-batch 6-yr cycle for each of three proposed ThO{sub 2}-UO{sub 2} mixtures with the UO{sub 2} enriched to 19.5% {sup 235}U are presented. Neutronic results show that fuels fabricated from ThO{sub 2}-UO{sub 2} mixtures can reach an average discharge burnup of up to 70 MWd/kgHM, which will increase the time between refueling and decrease the production of weapons-grade plutonium by a factor of 3 as compared to all-urania fuel.A version of FRAPCON-3, modified to handle pure thoria and ThO{sub 2}-UO{sub 2} mixtures, was used for the fuel performance and behavior calculations. The new version called FRAPCON-3Th includes the updated material property models for thermal conductivity, specific heat capacity, emissivity, thermal expansion, modulus of elasticity, and melting temperature to predict fuel behavior for pure ThO{sub 2} or ThO{sub 2}/UO{sub 2} mixed fuel. For a concentration of 75% ThO{sub 2}/25% UO{sub 2}, initial fuel performance parameters (peak centerline temperature, gap conductance, thermal expansion, etc.) predicted operating conditions are better than those of current UO{sub 2} fuel. A ThO{sub 2}-ThO{sub 2}/UO{sub 2} thermal conductivity model is still in the development stage. For all fuel calculations, an interim model that interpolates between the Belle and Berman predicted thermal conductivity using a correction factor for radiant heat transport and the MATPRO-predicted thermal conductivity for UO{sub 2} was applied.
- OSTI ID:
- 20826729
- Journal Information:
- Nuclear Technology, Vol. 137, Issue 2; Other Information: Copyright (c) 2006 American Nuclear Society (ANS), United States, All rights reserved. http://epubs.ans.org/; Country of input: International Atomic Energy Agency (IAEA); ISSN 0029-5450
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BURNUP
ECONOMICS
EMISSIVITY
FUEL CYCLE
FUEL PINS
MELTING POINTS
MIXED OXIDE FUELS
MONTE CARLO METHOD
NUCLEAR POWER PLANTS
PERFORMANCE
PLUTONIUM
REACTIVITY
SPECIFIC HEAT
STEADY-STATE CONDITIONS
THERMAL CONDUCTIVITY
THERMAL EXPANSION
THORIUM OXIDES
URANIUM 235
URANIUM DIOXIDE