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Full-Text Articles in Nuclear Engineering
Beta-Delayed Neutron Data And Models For Scale, Kemper Dyar Talley
Beta-Delayed Neutron Data And Models For Scale, Kemper Dyar Talley
Doctoral Dissertations
Recent advancements in experimental and theoretical nuclear physics have yielded new data and models that more accurately describe the decay of fission products compared to historical data currently used for many applications. This work examines the effect of the adopting the Effective Density Model theory for beta-delayed neutron emission probability on calculations of delayed-neutron production and fission product nuclide concentrations after fission bursts as well as the total delayed neutron fraction in comparison with the Keepin 6-group model. We use ORIGEN within the SCALE code package for these calculations. We show quantitative changes to the isotopic concentrations for fallout nuclides …
A Generalized Method For Fissile Material Characterization Using Short-Lived Fission Product Gamma Spectroscopy, Justin Richard Knowles
A Generalized Method For Fissile Material Characterization Using Short-Lived Fission Product Gamma Spectroscopy, Justin Richard Knowles
Doctoral Dissertations
Characterizing the fissile content of nuclear materials is of particular interest to the safeguards and nuclear forensics communities. Short-lived fission product gamma spectroscopy offers a significant reduction in analysis time and detection limits when compared to traditional non-destructive assay measurements. Through this work, a fully generalizable method that can be applied to variations in fissile compositions and neutron spectra was developed for the modeling and measurement of short-lived fission product gamma-rays. This method uses a 238-group neutron flux that was characterized for two pneumatic tube positions in the High Flux Isotope Reactor using flux monitor irradiations. This flux spectrum was …
Characterizing Local Order And Physical Properties Of Rare Earth Complex Oxides, Thomas Jacob Shamblin
Characterizing Local Order And Physical Properties Of Rare Earth Complex Oxides, Thomas Jacob Shamblin
Doctoral Dissertations
With more than 500 compositions, materials possessing the pyrochlore structure have a myriad of technological applications and physical phenomena. Three of the most noteworthy properties are the structure’s ability to resist amorphization making it a possible host matrix for spent nuclear fuel, its exotic magnetic properties arising from geometric frustration, and fast ionic conductivity for solid-oxide fuel cell applications. This work focuses on these three aspects of the pyrochlore’s many potential uses. Structural characterization revealed that pyrochlore-type oxides have a tendency to disorder from a high symmetry cubic structure to a lower symmetry orthorhombic arrangement in response to a variety …
Actinium-225 Production Via Proton Irradiation Of Thorium-232, Justin Reed Griswold
Actinium-225 Production Via Proton Irradiation Of Thorium-232, Justin Reed Griswold
Doctoral Dissertations
High energy proton spallation reactions on natural thorium metal targets have been utilized to produce multi mCi [milliCurie] quantities of Actinium-225. Theoretical cross sections for actinium and thorium isotopes as well as for a select number of the fission products produced in these reactions were generated by the Monte Carlo radiation transport code PHITS to simulate the experimental data obtained from sixteen irradiations of thorium metal targets with 25-210 µA [microampere] proton beams ranging in energies from 77 to 192 MeV. Irradiations were conducted at Brookhaven National Laboratory (BNL) and Los Alamos National Laboratory (LANL), while target dissolution and processing …