Efficient Coupled Transport-Depletion Sequence Using Hybrid Monte Carlo-Reduced Order Scheme

dc.contributor.advisor Kotlyar, Dan
dc.contributor.author Johnson, Andrew
dc.contributor.committeeMember Petrovic, Dr. Bojan
dc.contributor.committeeMember Erickson, Dr. Anna
dc.contributor.committeeMember Romano, Dr. Paul
dc.contributor.committeeMember Maldonado, Dr. G. Ivan
dc.contributor.department Mechanical Engineering
dc.date.accessioned 2022-01-14T16:04:24Z
dc.date.available 2022-01-14T16:04:24Z
dc.date.created 2020-12
dc.date.issued 2020-12-06
dc.date.submitted December 2020
dc.date.updated 2022-01-14T16:04:24Z
dc.description.abstract In nuclear engineering, the topic of depletion involves modeling time-dependent material compositions in a nuclear system, such as a power plant. During operation, isotopes decay and are transmuted according to local reaction rates, leading to a constantly changing nuclide inventory. Modern analysis tools employ a two-step approach, where steady state neutron transport solutions are coupled with depletion solvers. By assuming constant reaction rates over a time step, coupling schemes do not accurately model the time dependence needed to capture the time-evolution of compositions. Furthermore, prohibitively small time steps must be used for some problems (e.g. 3D core), else numerical instabilities and oscillations may arise. In this research, a hybrid approach has been developed, implemented and tested. The method utilizes reduced-order methods to deplete at sub-intervals between high-fidelity Monte Carlo simulations. The reduced-order simulations obtain reaction rates that better reflect the spatial and temporal neutron flux distributions, without many expensive transport solutions. This fine time scale greatly reduces and in some cases eliminates the oscillatory behavior for instability-prone problems. In such cases, the hybrid method leads to a tenfold increase in accuracy. If the reduced-order solver is orders of magnitude faster than the Monte Carlo solver, this increase is obtained for little to no computational cost. This hybrid scheme has been implemented and tested using a custom framework, with an extensible interface for additional transport solvers. By holding a reactor model in memory, both high-fidelity and reduced-order methods can fully represent the problem in a consistent manner. The framework and the hybrid method contained therein have been compared to a stability limited test case and a practical reactor engineering problem, both demonstrating the tangible benefits of this novel coupling scheme.
dc.description.degree Ph.D.
dc.format.mimetype application/pdf
dc.identifier.uri http://hdl.handle.net/1853/65996
dc.language.iso en_US
dc.publisher Georgia Institute of Technology
dc.subject Depletion
dc.subject Monte Carlo
dc.subject Dybrid methods
dc.subject Duclear engineering
dc.title Efficient Coupled Transport-Depletion Sequence Using Hybrid Monte Carlo-Reduced Order Scheme
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.advisor Kotlyar, Dan
local.contributor.corporatename George W. Woodruff School of Mechanical Engineering
local.contributor.corporatename College of Engineering
relation.isAdvisorOfPublication f262f38e-5ea1-4dca-a1dc-e6d3f944a0ea
relation.isOrgUnitOfPublication c01ff908-c25f-439b-bf10-a074ed886bb7
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
thesis.degree.level Doctoral
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