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dc.contributor.authorHudson, Nathanael Harrisonen_US
dc.date.accessioned2006-09-01T19:19:42Z
dc.date.available2006-09-01T19:19:42Z
dc.date.issued2006-05-19en_US
dc.identifier.urihttp://hdl.handle.net/1853/11485
dc.description.abstractAn accurate and computationally fast method to generate nodal cross sections for the Pebble Bed Reactor (PBR) was presented. In this method, named Spectral History Correction (SHC), a set of fine group microscopic cross section libraries, pre-computed at specified depletion and moderation states, was coupled with the nodal nuclide densities and group bucklings to compute the new fine group spectrum for each node. The relevant fine group cross-section library was then recollapsed to the local broad group cross-section structure with this new fine group spectrum. This library set was tracked in terms of fuel isotopic densities. Fine group modulation factors (to correct the homogeneous flux for heterogeneous effects) and fission spectra were also stored with the cross section library. As the PBR simulation converges to a steady state fuel cycle, the initial nodal cross section library becomes inaccurate due to the burnup of the fuel and the neutron leakage into and out of the node. Because of the recirculation of discharged fuel pebbles with fresh fuel pebbles, a node can consist of a collection of pebbles at various burnup stages. To account for the nodal burnup, the microscopic cross sections were combined with nodal averaged atom densities to approximate the fine group macroscopic cross-sections for that node. These constructed, homogeneous macroscopic cross sections within the node were used to calculate a numerical solution for the fine group spectrum with B1 theory. This new fine spectrum was used to collapse the pre-computed microscopic cross section library to the broad group structure employed by the fuel cycle code. This SHC technique was developed and practically implemented as a subroutine within the PBR fuel cycle code PEBBED. The SHC subroutine was called to recalculate the broad group cross sections during the code convergence. The result was a fast method that compared favorably to the benchmark scheme of cross section calculation with the lattice cross-section generator for two PBR reactor designs.en_US
dc.format.extent369333 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.publisherGeorgia Institute of Technologyen_US
dc.subjectCross sectionsen_US
dc.subjectNodal
dc.subjectSpectral history
dc.subjectPebble bed reactor
dc.subjectLeakage
dc.subjectDepletion
dc.subjectPBR
dc.subjectPEBBED
dc.titleThe Correction of Pebble Bed Reactor Nodal Cross Sections for the Effects of Leakage and Depletion Historyen_US
dc.typeDissertationen_US
dc.description.degreePh.D.en_US
dc.contributor.departmentNuclear and Radiological Engineeringen_US
dc.description.advisorCommittee Chair: Rahnema, Farzad; Committee Member: Goldsztein, Guillermo; Committee Member: Ougouag, Abderrafi; Committee Member: Stacey, Weston; Committee Member: Wang, C.-K. Chrisen_US


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