The eff ect of the inclusion of BeO to the fuel pellets has been modelled. The system modelled kept the mass of uranium-235, the energy generating isotope, constant as compared to a normal pellet , but included 10% BeO by volume. The modelled results of this composition pellet are dramatic. At the simulated average power density, the temperature at the centerline of the pellet, the hottest point, was decreased by 200oC from 800oC to 600oC while keeping the surface temperature constant. This is crucial as it is the surface temperature of the pellets which determine their power output. Therefore, the same power is generated, but with a far lower centerline temperature than in a tradition UO2 fuel pellet. This reduces the likelyhood of cladding interaction as well as cracking of the pellets due to uneven thermal expansion. It also means that the average temperature of the pellet is reduced by approximately 100oC.
The fuel pellets, at a given amount of U-235, can last longer, requiring less frequent refueling, or the amount of U-235 could actually be decreased, allowing the same refueling schedule to be used. It is currently estimated that these improvements could directly lead to a 4% reduction in fuel consumption.
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