Department of Nuclear Engineering and Radiation Health Physicshttp://hdl.handle.net/1957/184962016-02-10T19:50:38Z2016-02-10T19:50:38ZNumerical computation of discrete differential scattering cross sections for Monte Carlo charged particle transportWalsh, Jonathan A.Palmer, Todd S.Urbatsch, Todd J.http://hdl.handle.net/1957/581312016-01-22T20:58:58Z2015-12-15T00:00:00ZNumerical computation of discrete differential scattering cross sections for Monte Carlo charged particle transport
Walsh, Jonathan A.; Palmer, Todd S.; Urbatsch, Todd J.
We investigate a method for numerically generating discrete scattering cross sections for use in charged
particle transport simulations. We describe the cross section generation procedure and compare it to
existing methods used to obtain discrete cross sections. The numerical approach presented here is generalized
to allow greater flexibility in choosing a cross section model from which to derive discrete
values. Cross section data computed with this method compare favorably with discrete data generated
with an existing method. Additionally, a charged particle transport capability is demonstrated in the
time-dependent Implicit Monte Carlo radiative transfer code, Milagro. We verify the implementation of
charged particle transport in Milagro with analytic test problems and we compare calculated electron
depth–dose profiles with another particle transport code that has a validated electron transport capability.
Finally, we investigate the integration of the new discrete cross section generation method with the
charged particle transport capability in Milagro.
To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/nuclear-engineering-and-design/
2015-12-15T00:00:00ZA novel approach to modeling plate deformations in fluid-structure interactionsHoward, T. K.Marcum, W. R.Jones, W. F.http://hdl.handle.net/1957/578632015-12-08T16:23:40Z2015-11-01T00:00:00ZA novel approach to modeling plate deformations in fluid-structure interactions
Howard, T. K.; Marcum, W. R.; Jones, W. F.
As computational power increases, so does the desire to use computational simulations while designing fuel plates. The downside is multi-physics simulations – or more specifically, fluid–structure interactions (FSI) as addressed herein – require a larger amount of computational resources. Current simulations of a single plate can take weeks on a desktop computer, thus requiring the use of multiple servers or a cluster for FSI simulations. While computational fluid dynamic (CFD) codes coupled to computational structural mechanics (CSM) codes can provide a wealth of information regarding flow patterns, there should be some skepticism in whether or not they are the only means of achieving the desired solution. When the parameters of interest are the onset of plate collapse and the associated fluid channel velocities, coupled CFD–CSM simulations provide superfluous information. The paper provides an alternative approach to solving FSI problems using a 1-D, semi-analytical model derived from first principles. The results are compared and contrasted to the numerical and experimental work performed by Kennedy et al. (2014. Experimental Investigation of Deflection of Flat Aluminium Plates Under Variable Velocity Parallel Flow, Columbia: University of Missouri TherMec Research Group).
To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/nuclear-engineering-and-design/
2015-11-01T00:00:00ZTemporal gamma-ray spectrometry to quantify relative fissile material contentWilliford, Russell S.http://hdl.handle.net/1957/410422013-07-24T15:10:37Z2013-06-24T00:00:00ZTemporal gamma-ray spectrometry to quantify relative fissile material content
Williford, Russell S.
A new method for delayed gamma-ray spectrometry to quantify the relative content of fissile material is developed and demonstrated to support international efforts in bolstering non-destructive assay capabilities. Previous traditional delayed gamma-ray spectrometry techniques rely upon nuclear data that often carry very high uncertainty. The new method removes the requirement for nuclear data by using the time-dependent decay characteristics of key fission fragment peaks. Having developed the theory and algorithm, the method is demonstrated using empirical fission data to estimate the contents of fissile materials of different compositions. The resultant estimates are accurate within 2% of the actual contents and precise within 2%.
Graduation date: 2014
2013-06-24T00:00:00ZFeasibility study on a soluble boron-free small modular reactorMart, Justin R.http://hdl.handle.net/1957/410042013-07-23T17:43:29Z2013-06-14T00:00:00ZFeasibility study on a soluble boron-free small modular reactor
Mart, Justin R.
The elimination of soluble boron creates several advantages for Small Modular Reactor (SMR) operation. Most of these advantages are realized through significant core simplification (removal of pipes, pumping, and purification systems), the removal of the corrosive effects of soluble boron, and from improved safety effects. However, removing soluble boron creates its own set of specific challenges that must be overcome. Traditional pressurized water reactors employ soluble boron for uniform power suppression throughout the core. Thus any boron-free SMR design requires increased dependence on control rods and burnable poisons, where both are discrete neutron absorbers that locally impact the core where they are inserted. Since control rods are partially inserted, their presence negatively impacts the axial power profile and this distortion creates undesirable power peaks, leading to a reduced operating margin and a significant economic burden. Thus, the main challenge in any boron free design concerns excess reactivity suppression and active reactivity control while maintaining a proper axial power profile and reduced power peaks. The goal of the feasibility study is to investigate the physical effects of removing soluble boron, and to investigate and identify an effective strategy for containing power peaks in a boron-free SMR. Studsvik's CASMO-4E was employed to solve 2-D Transport equation for infinite lattice analysis, and SIMULATE-3K was employed to solve 3-D nodal diffusion equation for full core analysis. The study identified improved reactivity feedback mechanisms associated with the removal of soluble boron, arising from a softened neutron flux and a decreased production of plutonium. An analysis of strategies for soluble boron-free operation that involved axially grading burnable poisons and U²³⁵ enrichment percentages was found unable to be able to control the axial power profile throughout core lifetime. The inherent limitations in the lifetime of burnable poisons resulted in an inability to control the axial power profile through middle and end of cycle. Investigations of additional strategies involving an advanced control rod algorithm produced significantly improved results that met the prescribed criteria for success. The advanced control rod algorithm is thus recognized as a viable strategy for boron-free operation for SMRs.
Graduation date: 2014
2013-06-14T00:00:00Z