Fully Coupled Simulation of Oxygen and Heat Diffusion for (U,Pu)O2 Fuel in Both Fast-Breeder Reactor and Light-Water Reactor

2015 ◽  
Vol 1 (4) ◽  
Author(s):  
Wenzhong Zhou ◽  
Rong Liu
Keyword(s):  
High Temperature ◽  
Power Distribution ◽  
Heat Diffusion ◽  
Light Water Reactor ◽  
Fast Breeder Reactor ◽  
Light Water ◽  
Water Reactor ◽  
Ratio Change ◽  
Overall Performance ◽  
Fully Coupled

Oxygen redistribution with a high-temperature gradient is an important fuel performance concern in fast-breeder reactor (FBR) and light-water reactor (LWR) (U,Pu)O2 fuel under irradiation, and affects fuels properties, power distribution, and fuel overall performance. This paper studies the burnup dependent oxygen and heat diffusion behavior in a fully coupled way within (U,Pu)O2 FBR and LWR fuels. The temperature change shows relatively larger impact on oxygen to metal (O/M) ratio redistribution rather than O/M ratio change on temperature, whereas O/M ratio redistributions show different trends for FBR and LWR fuels due to their different deviations from the stoichiometry of oxygen under high-temperature environments.

Fully Coupled Simulation of Oxygen and Heat Diffusion for (U, Pu)O2 Fuel in Both FBR and LWR

2014 ◽  
Author(s):  
Wenzhong Zhou ◽  
Rong Liu
Keyword(s):  
Fast Reactor ◽  
Outer Surface ◽  
Heat Diffusion ◽  
Light Water Reactor ◽  
Fuel Temperature ◽  
Ratio Distribution ◽  
Light Water ◽  
Water Reactor ◽  
Metal Ratio ◽  
Reactor Application

Oxygen redistribution with the high temperature gradient is one of the important fuel performance concerns in fast reactor (FBR) and light water reactor (LWR) oxide (U, Pu)O2 fuel during irradiation, and will affect nuclear fuel materials properties, power distribution and overall performance of the fuel. This paper focuses on the oxygen and heat diffusion within (U, Pu)O2 fast reactor and light water reactor fuel. In this study, the correlations from the literature are used for density, thermal conductivity, specific heat, and oxygen to metal ratio redistribution. Three dimensional burnup dependent oxygen diffusion and heat diffusion models are fully-coupled in steady states and transients to account for the effects on each other. The models are implemented into COMSOL Multiphysics to perform this analysis. The simulation results show that the temperature profile change has relatively larger impact on oxygen/metal ratio distribution compared to oxygen/metal ratio distribution change’s impact on temperature distribution. With regard to the oxygen/metal ratio’s effect on temperature distribution, fast reactor and light water reactor show different trends. For fast reactor application, with the oxygen/metal ratio’s increase on the outer surface, the fuel temperature decreases. However, for light water reactor application, with the oxygen/metal ratio increase on the outer surface, the fuel temperature increases, which is opposite to fast reactor application. For different oxygen/metal ratio boundary conditions, with the oxygen/metal ratio increase on the outer surface, the oxygen/metal ratio increases over the whole fuel. For the fast reactor application, the inner surface has the lowest oxygen/metal ratio, and the outer surface has the highest oxygen/metal ratio. However, this trend in light water reactor application is exactly opposite to fast reactor application. For the start-up transient scenario, the rapid changes in time-dependent temperature and oxygen/metal ratio distributions are observed, which are due to a rapid change in heat generation. Comparing fast reactor and light water reactor simulation results, we can observe that the temperature change is relatively more obvious in light water reactor than fast reactor.

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