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46 results on '"DeVol, Timothy A."'

4. Organic Vacuum Pump Fluids for the Vacuum Pumping of Fusion Power Plants

Author

Guin, Tyler, McDonald, Kori, Folkert, James, Verst, Chris, Gaillard, Jay, DeVol, Timothy A., Bliznyuk, Valery N., and Larsen, George

Abstract

AbstractVacuum pumps are the heart of the fusion fuel cycle, but most currently proposed pumping technologies are not capable of handling the required flow rates and vacuum pressures. Oil-containing vacuum pumps can readily meet the flow requirements, but vacuum fluids will degrade in fusion-relevant environments due to contact with tritium and exposure to high-energy radiation. Here, we describe a methodology to screen vacuum fluid candidates and purify these candidate fluids post oxidation, post exposure to deuterium, and post exposure to gamma radiation (<7.5 MGy) to simulate a process in which vacuum fluids can be recovered and regenerated during the fusion fuel cycle. A series of oils, including a highly purified mineral oil, phenyl silicone oil, and a polyphenyl ether, are shown to be suitable candidates for vacuum pumping. Additionally, we describe a simple purification methodology to remove oxidized functionalities and the associated isotopologues induced by contact with deuterium from the candidate vacuum fluids This purification methodology can also be applied to radiological damage with moderate effect. Finally, we demonstrate that the sorbents can be regenerated through electromagnetic microwave digestion.

Published
2024
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25. Plastic Scintillators and Radiation Detectors Based on Triphenyl Pyrazoline Derivatives.

Author

Bliznyuk, Valery N., Seliman, Ayman F., Derevyanko, Nadezhda A., Dugan, Andrew, Ishchenko, Alexander A., and DeVol, Timothy A.

Subjects
FLUORESCENCE yield, OPTICAL fiber cladding, GAMMA rays, NUCLEAR counters, FORM perception, VINYL polymers, SCINTILLATORS
Abstract

Plastic scintillators (PS) allow design of portative lightweight devices for quantification of low‐activity radiation sources. We have recently suggested a new type of organic fluorophores based on triphenyl pyrazoline (PZ) derivatives with high fluorescence quantum yield showing high radioluminescence when combined with a polyvinyltoluene (PVT) matrix. In this publication we report on radioluminescence properties of the PZ−X family with various halogen substitution (X=F, Cl, Br, I), or having vinyl functional group (vPZ, X=vinyl). PS based on such fluorophores and PVT matrix can be prepared as bulk samples, micrometer size beads or cladding on optical fibers. Application of fluorophores with vinyl functional groups enabled their enhanced interaction with the matrix due to covalent bonding between the components. We demonstrate high performance of PZ−X fluorophores and especially vPZ fluorophore in fabrication of nanocomposites for detection of various types of radiation. Scintillators have enhanced gamma ray detection capabilities with an addition of triphenyl Bi, or Gd2O3 nanoparticles. High fluorescence quantum yield and luminosity of PZ fluorophores allows dramatical reduction of their content in PS systems. Mechanisms of energy transfer and conversion during scintillation process are discussed. Special consideration is given to enhancement of α/β and neutron/gamma (n/γ) pulse shape discrimination (PSD) function of the developed scintillators. [ABSTRACT FROM AUTHOR]

Published
2022
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26. Integration of ecosystem science into radioecology : A consensus perspective

Author

Rhodes, Olin E., Brechignac, Francois, Bradshaw, Clare, Hinton, Thomas G., Mothersill, Carmel, Arnone, John A., Aubrey, Doug P., Barnthouse, Lawrence W., Beasley, James C., Bonisoli-Alquati, Andrea, Boring, Lindsay R., Bryan, Albert L., Capps, Krista A., Clement, Bernard, Coleman, Austin, Condon, Caitlin, Coutelot, Fanny, DeVol, Timothy, Dharmarajan, Guha, Fletcher, Dean, Flynn, Wes, Gladfelder, Garth, Glenn, Travis C., Hendricks, Susan, Ishida, Ken, Jannik, Tim, Kapustka, Larry, Kautsky, Ulrik, Kennamer, Robert, Kuhne, Wendy, Lance, Stacey, Laptyev, Gennadiy, Love, Cara, Manglass, Lisa, Martinez, Nicole, Mathews, Teresa, McKee, Arthur, McShea, William, Mihok, Steve, Mills, Gary, Parrott, Ben, Powell, Brian, Pryakhin, Evgeny, Rypstra, Ann, Scott, David, Seaman, John, Seymour, Colin, Shkvyria, Maryna, Ward, Amelia, White, David, Wood, Michael D., Zimmerman, Jess K., Rhodes, Olin E., Brechignac, Francois, Bradshaw, Clare, Hinton, Thomas G., Mothersill, Carmel, Arnone, John A., Aubrey, Doug P., Barnthouse, Lawrence W., Beasley, James C., Bonisoli-Alquati, Andrea, Boring, Lindsay R., Bryan, Albert L., Capps, Krista A., Clement, Bernard, Coleman, Austin, Condon, Caitlin, Coutelot, Fanny, DeVol, Timothy, Dharmarajan, Guha, Fletcher, Dean, Flynn, Wes, Gladfelder, Garth, Glenn, Travis C., Hendricks, Susan, Ishida, Ken, Jannik, Tim, Kapustka, Larry, Kautsky, Ulrik, Kennamer, Robert, Kuhne, Wendy, Lance, Stacey, Laptyev, Gennadiy, Love, Cara, Manglass, Lisa, Martinez, Nicole, Mathews, Teresa, McKee, Arthur, McShea, William, Mihok, Steve, Mills, Gary, Parrott, Ben, Powell, Brian, Pryakhin, Evgeny, Rypstra, Ann, Scott, David, Seaman, John, Seymour, Colin, Shkvyria, Maryna, Ward, Amelia, White, David, Wood, Michael D., and Zimmerman, Jess K.

Abstract

In the Fall of 2016 a workshop was held which brought together over 50 scientists from the ecological and radiological fields to discuss feasibility and challenges of reintegrating ecosystem science into radioecology. There is a growing desire to incorporate attributes of ecosystem science into radiological risk assessment and radioecological research more generally, fueled by recent advances in quantification of emergent ecosystem attributes and the desire to accurately reflect impacts of radiological stressors upon ecosystem function. This paper is a synthesis of the discussions and consensus of the workshop participant's responses to three primary questions, which were: 1) How can ecosystem science support radiological risk assessment? 2) What ecosystem level endpoints potentially could be used for radiological risk assessment? and 3) What inference strategies and associated methods would be most appropriate to assess the effects of radionuclides on ecosystem structure and function? The consensus of the participants was that ecosystem science can and should support radiological risk assessment through the incorporation of quantitative metrics that reflect ecosystem functions which are sensitive to radiological contaminants. The participants also agreed that many such endpoints exit or are thought to exit and while many are used in ecological risk assessment currently, additional data need to be collected that link the causal mechanisms of radiological exposure to these endpoints. Finally, the participants agreed that radiological risk assessments must be designed and informed by rigorous statistical frameworks capable of revealing the causal inference tying radiological exposure to the endpoints selected for measurement.

Published
2020
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27. Integration of ecosystem science into radioecology: A consensus perspective

Author

Rhodes, Olin E., primary, Bréchignac, Francois, additional, Bradshaw, Clare, additional, Hinton, Thomas G., additional, Mothersill, Carmel, additional, Arnone, John A., additional, Aubrey, Doug P., additional, Barnthouse, Lawrence W., additional, Beasley, James C., additional, Bonisoli-Alquati, Andrea, additional, Boring, Lindsay R., additional, Bryan, Albert L., additional, Capps, Krista A., additional, Clément, Bernard, additional, Coleman, Austin, additional, Condon, Caitlin, additional, Coutelot, Fanny, additional, DeVol, Timothy, additional, Dharmarajan, Guha, additional, Fletcher, Dean, additional, Flynn, Wes, additional, Gladfelder, Garth, additional, Glenn, Travis C., additional, Hendricks, Susan, additional, Ishida, Ken, additional, Jannik, Tim, additional, Kapustka, Larry, additional, Kautsky, Ulrik, additional, Kennamer, Robert, additional, Kuhne, Wendy, additional, Lance, Stacey, additional, Laptyev, Gennadiy, additional, Love, Cara, additional, Manglass, Lisa, additional, Martinez, Nicole, additional, Mathews, Teresa, additional, McKee, Arthur, additional, McShea, William, additional, Mihok, Steve, additional, Mills, Gary, additional, Parrott, Ben, additional, Powell, Brian, additional, Pryakhin, Evgeny, additional, Rypstra, Ann, additional, Scott, David, additional, Seaman, John, additional, Seymour, Colin, additional, Shkvyria, Maryna, additional, Ward, Amelia, additional, White, David, additional, Wood, Michael D., additional, and Zimmerman, Jess K., additional

Published
2020
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34. Rapid Sample Preparation for Alpha Spectroscopy with Ultrafiltration Membranes

Author

Duval, Christine E., Darge, Abenazer W., Ruff, Cody, DeVol, Timothy A., and Husson, Scott M.

Abstract

This contribution describes a rapid, fieldable alpha spectroscopy sample preparation technique that minimizes consumables and decreases the nuclear forensics timeline. Functional ultrafiltration membranes are presented that selectively concentrate uranium directly from pH 6 groundwater and serve as the alpha spectroscopy substrate. Membranes were prepared by ultraviolet grafting of uranium-selective polymer chains from the membrane surface. Membranes were characterized by Fourier-transform infrared spectroscopy before and after modification to support functionalization. Membrane performance was evaluated using uranium-233 or depleted uranium in both deionized and simulated groundwater at pH 6. Functionalized membranes achieved peak energy resolutions of 31 ± 2 keV and recoveries of 81 ± 4% when prepared directly from pH 6 simulated groundwater. For simulated groundwater spiked with depleted uranium, baseline energy resolution was achieved for both isotopes (uranium-238 and uranium-234). The porous, uranium-selective substrate designs can process liters per hour of uranium-contaminated groundwater using low-pressure (<150 kPa) filtration and a 45 mm diameter membrane filter, leading to a high-throughput, one-step concentration, purification, and sample mounting process.

Published
2024
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35. Macromol. Mater. Eng. 6/2018

Author

Bliznyuk, Valery N., primary, Seliman, Ayman F., additional, Husson, Scott M., additional, Lvov, Yuri M., additional, and DeVol, Timothy A., additional

Published
2018
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46. Cobalt-60, Barium-133, Cesium-137, and Europium-152 migration from cementitious sources through sediment under field conditions.

Author

Williams RF, Kaplan DI, Erdmann BJ, DeVol TA, and Powell BA

Abstract

Safe and effective storage of radioactive waste is essential to protect human and environmental health. Due to the potential for accidental releases and the severity of the associated risks, it is imperative to further understand radionuclide transport should an accident occur. This study was the second set of measurements conducted in 2022 of an ongoing experiment that has analyzed the vadose zone migration of radionuclides from cementitious wasteforms at the Savannah River Site over the last ten years. The radionuclides introduced within the sources are prominent constituents of radioactive waste or analogs for other groups or series of radionuclides. Lysimeters were first analyzed in 2016 using a collimated high-purity germanium gamma-ray spectrometer to non-destructively measure the concentration of each radionuclide in the sediment column as a function of depth. Following these measurements, the lysimeters were redeployed for another 4 years. All radionuclides in all lysimeters were observed to transport further during the redeployment period; however, the extent of migration varied with the material used for introduction. Except for 137 Cs, migration through the sediment control system increased with decreasing ionic potential (ionic charge/radius); migration order: 152 Eu <  137 Cs <  60 Co <  133 Ba. Overall, the cementitious wasteforms were observed to decrease radionuclide migration extent relative to natural vadose zone conditions. In both cementitious wasteforms, the migration extent increased in the order 152 Eu <  133 Ba< 60 Co <  137 Cs. However, less migration was measured when the radionuclides were incorporated into a reducing grout wasteform. The novelty of this paper is the demonstration of a technique capable of creating non-destructive measurements over decade time scales. Ultimately, this work provides insight into the long-term migration of alkali, alkali earth, divalent transition metal, and trivalent (e.g., lanthanide and actinide element) isotopes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Published
2024
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