Determination of Radial Power Profiles in Thorium-Plutonium Mixed Oxide Fuel Pellets

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Examensarbete för masterexamen
Master Thesis
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2014
Författare
fredriksson, patrik
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Sammanfattning
To be able to license fuel for use in commercial nuclear reactors its thermomechanical behavior needs to be well known. For this, fuel performance codes need to be developed. The work described in this thesis was performed for the Norwegian company Thor Energy, and focuses on rewriting a subroutine calculating the radial power profile in the well-established fuel performance code FRAPCON so that it applies to thorium-plutonium mixed oxide fuel. This was done by extending the previous model, by introducing some nuclides important to the thorium fuel cycle, and remaking the calculation procedure of the neutron flux. The introduction of new nuclides imposed a need for adding new effective cross sections and for updating the existing ones in the code. Due to the large amount of cross sections and other parameters a genetic algorithm was used. Data for the genetic algorithm were gathered using a Monte Carlo-based reactor physics simulation code called Serpent. Several pin configurations were simulated with different radii, plutonium content and plutonium vector. The genetic algorithm found a set of cross sections which described the radial power profile very well for light water reactor conditions. A mean relative error of 0.57 % was observed. For halden boiling water reactor conditions the result was not equally good, with a mean relative error of 1.58 %, but was considered adequate for the present purpose. Implementing the new subroutine in FRAPCON improved the code’s predictive capacity for fuel pellet centerline temperatures, as indicated by benchmarking against an experimental data set.
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Energi, Beräkningsfysik, Teknisk fysik, Energy, Computational physics, Engineering physics
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