“Criticality safety benchmark evaluations require the creation of models that most accurately represent the experiment being evaluated. In some cases this can be relatively trivial with experiments containing rather simple or standard geometry. In others, such as packed bed systems, this becomes unique and a more difficult process. The importance of accurate modeling of packed bed systems for the use of criticality safety benchmark evaluations was looked at. Four models were created of various complexities and accuracy. First the multi-particle bed, consisting of a fuel particle (UC1.7 kernel with C shell) and two filler particles (Zircaloy-4 and C + S at 6.2 w/o) was homogenized to form a single material that filled the fuel region. The second model used the material created in the first model but now in the form of the spherical particles placed in a simple lattice and used to fill the fuel region. The third model separated the three materials into their individual particle types and placed them into a simple lattice to fill the fuel region at approximate particle fractions. The fourth model used the complex lattice cell created from 8 face centered cubic unit cells in a 2x2x2 arrangement as the base for the particle lattice. As model complexity increased the model multiplication factor decreased from 1.00240 in the homogenous model to 1.00135 in the complex lattice cell model approaching the experimental value of 1.0. It is expected that this is due to a combination of things such as self-shielding and changes to more accurate densities, packing fraction, material densities, and particle arrangement”--Abstract, page iii.
Alajo, Ayodeji Babatunde
Schlegel, Joshua P.
Mueller, Gary Edward, 1954-
Nuclear Engineering and Radiation Science
M.S. in Nuclear Engineering
Missouri University of Science and Technology
x, 51 pages
© 2021 Elijah Chamberlain Lutz, All rights reserved.
Thesis - Open Access
Lutz, Elijah Chamberlain, "Development of complex lattice cell in benchmark model of particle bed critical system" (2021). Masters Theses. 7995.