Global efforts to support non-uranium approaches for 99Mo production, due to the proliferation risks associated with 235U fission-based production methods, have recently taken huge strides towards fruition. Several linear accelerator-based methods are currently in late-stage development that can produce low specific activity 99Mo from enriched 98/100Mo targets. The development of...
Used Nuclear Fuel (UNF) contains transuranic (TRU) elements and numerous fission products as a result of the uranium fission process and neutron activation that occur in commercial light water power reactors. Recent environmental and nuclear proliferation concerns have spawned the development of advanced reprocessing techniques to close the nuclear fuel...
Spent nuclear fuel (SNF) resultant from the generation of nuclear power is a chemically and radiologically diverse system which is advantageous to chemically process prior to geologic disposal. Hydrometallurgy is the primary technology for chemical processing for light water reactor spent fuels, where spent fuel is dissolved in an acid...
Nowadays selective separation processes are sought after more than ever before. They are indispensable to meet the growing demand for individual rare earth elements, minor actinides partitioned from fission-produced lanthanides, as well as, overall, more concentrated and high-purity products. This research focuses on such separation techniques as solvent extraction which...
Industrial reprocessing of irradiated nuclear fuel (INF) is one of the most complex procedures performed on a large scale; the process is intricate due to the mix of radionuclides present in INF. As a global trend for nuclear power and reprocessing continues, research is geared toward optimizing the extraction of...
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Alena Paulenova
Industrial reprocessing of irradiated nuclear fuel (INF) is one of the
Production of 89Zr serves as a crucial preliminary step for exploring Zr-chelates, determining their stability constants, and advancing radiolabeling methodologies for monoclonal antibody based theranostics. 89Zr is typically produced by the irradiation of natural yttrium targets, a process extensively documented in scientific literature. Two primary methods are employed: the 89Y(p,n)89Zr...
This study investigated gel dosimetry with X-ray CT imaging as a possible means for extracting dose information from a 3D gel dosimeter. Currently Optical CT and MRI are the popular means of dose extraction, but X-ray CT imaging has the advantage of being more convenient and cost effective. The dosimetric...
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Alena Paulenova
This study investigated gel dosimetry with X-ray CT imaging as a
Neptunium, with its rich redox chemistry, has a special position in the chemistry of actinides. With a decades-long history of development of aqueous separation methods for used nuclear fuel (UNF), management of neptunium remains an unresolved issue because of its not clearly defined redox speciation. Neptunium is present in two,...
Uranium dioxide has been used in industry both as a fuel for power reactors and as a target for the production of radioisotopes. One of the most important radioisotopes produced using these targets is molybdenum-99 (Mo-99, 65.94hr half-life), which is the parent isotope to technetium-99m (Tc-99m, 6.01hr half-life), a radioisotope...
Microstructure changes in uranium and uranium/metal alloys due to radiation damage are of great interest in nuclear science and engineering. Titanium has attracted attention because of its similarity to Zr. It has been proposed for use in the second generation of fusion reactors due to its resistance to radiation-induced swelling....
In this work, three isomeric forms of N, N'-diethyl, N, N'-ditolyldipicolinamide (EtTDPA) were synthesized. The elements thorium through americium, which make up a significant portion of the actinides in used nuclear fuel (with the exception of curium), and two fission products, molybdenum and technetium, were tested for their ability to...
Iodine-129 is a key risk driver at sites where nuclear materials have been fabricated or processed, and it is a predominant isotope of concern in long-term waste storage strategies. I-129 exists primarily as iodate in the subsurface at the Hanford Site in south-central Washington State. Between 15 and 40% of...
Carboxylic acids have played an important role in the field of actinide (An) and lanthanide (Ln) separations and the reprocessing of irradiated nuclear fuel. Recent bench-scale experiments have demonstrated that 3-carboxy-3-hydroxypentanedioic acid (citric acid) is a promising aqueous complexant that can effectively aid in the separation of transition metals from...
Chitosan is a biopolymer resulting from the deacetylation of chitin, the second most abundant biopolymer in nature. Chitosan has been successfully used in systems to remove metal ions and other pollutants from wastewater. Chitosan has shown promise as a sorbent for radionuclides in some aqueous waste streams.
The sorption of...
Effective separation of lanthanides (Ln) from the minor actinides (MA) is a crucial technical challenge to closing the nuclear fuel cycle. This separation is a necessary prerequisite to transmute long-lived isotopes of Am and Cm, which will allow a reduction of the repository volume, thermal load, and radiological toxicity of...
Partitioning of trivalent actinides (in particular, americium and curium) from the
fission produced light lanthanides is a major concern of used nuclear fuel reprocessing for
the purposes of waste disposal. Several solvent extraction processes have been developed
to address these chemically difficult separations. The historically employed TALSPEAK
Process utilizes di-2-ethylhexyl...
Pyroprocessing is an advanced technology for recycling used nuclear fuel. Pyrochemical processes encompass a wide range of chemical, physical, and electrochemical methods to partition fission products and other components from used nuclear fuel, which allows for the reuse of the actinides in nuclear fuel. This dissertation investigates two chemical systems...
This thesis presents an approach to develop innovative methods for decontamination and surface protection applicable to naval nuclear ships and potentially, personnel, replacing antiquated techniques. To accomplish this goal, two products manufactured by CBI Polymers, LLC., DeconGel™ 1101 (1101) and a shampoo, DeconGel™ "prototype" (prototype), were tested.
The prototype was...
An alternative extractant for the TRUEX/UNEX process was investigated in solid phase extraction chromatography. The para and ortho isomers of diamides derivatives of dipicolinic acid (N,N'-diethyl-N,N'-ditolyl-dipicolinamide, EtTDPA) have been found in the past to effectively separate actinides from lanthanides in solvent extraction and were successfully impregnated on two uncoated, inert...
The goal of Advanced Fuel Cycle Initiative program is to efficiently separate and recover actinides in attempts to reprocess irradiated nuclear fuel and reduce the necessary storage volume. In order to facilitate large-scale industrial
applications of liquid-liquid separation processes, knowledge of the thermodynamic constants associated with the distribution of metal...
The radiolytic changes in oxidation state for solutions of initially Np(V) and/or Np(VI) were investigated by gamma-irradiation in conjunction with UV/Vis spectroscopy of the aqueous phase. Samples were irradiated in varying concentrations of nitric acid, and with or without the presence of 30 % TBP in dodecane. At short irradiation...
Internal dosimetry is challenging and relies on estimates using MIRD or ICRP biokinetic models. To address this, we looked at gene expression analysis in whole blood from radiotherapy patients. Patients with relapsed or refractory neuroblastoma who received ¹³¹I-mIBG at UCSF were used to correlate internal ionizing radiation (IR) dose with...
Nanostructured material has been projected to be the next generation material for the detection of ionizing radiation due to the uniquely superior physical processes associated with charge creation and by virtue of their optoelectronic tunablility. Semiconducting Nanocrystal (NC) detectors, by nature of their low band gap material, low fabrication costs,...
Recent experiments have advanced the current understanding of multi-nucleon transfer(MNT) reactions. Within nuclear science, most nuclear reaction experiments consist of a stationary target material, that is then bombarded by a moving projectile. Overall nuclear reactions can be used to produce a desired isotope. In the case of this particular study...
Aqueous complexation of Th(IV), U(IV), Np(IV), Pu(III/IV), and Ce(III/IV) with DTPA was studied by potentiometry, absorption spectrophotometry, and cyclic voltammetry at 1 M ionic strength and 25 °C. The stability constants for the 1:1 complex of each trivalent and tetravalent metal were calculated. From the potentiometric data, we report stability...
The Hi-CLIMB broadband seismic experiment (2002-2005) operated 233 stations along an 800 km long north-south line from the Himalayan foreland into the central Tibetan Plateau and in a 350x350 km sub-array within southern Tibet and central and eastern Nepal. Station spacing was approximately 8 km along the line and 50...
Environmental modeling as a result of the Fukushima accident has been at the forefront for present day health physics. The accident released radionuclides in the environment and the fate and transport of these radionuclides are of interest when considering doses to non-human biota. The Pale Grass Blue Butterfly was studied...
The objective of this research was to estimate the radiological impact on various non-human biotas by the Fukushima Daiichi Nuclear power plant radiation release resulting from Japan's tsunami in March 2011 consistent with the recent recommendations of the International Commission on Radiological Protection. Soil concentration data given by Japan's Ministry...
Natural ground color is useful for reference maps as well as maps where a realistic representation of the Earth's surface matters. Natural color schemes are less likely to be misinterpreted, as opposed to hypsometric color schemes, and are generally preferred by map readers. The creation of natural-color maps was once...
In the last decade regulatory bodies have begun to implement standards to protect populations of non-human biota (NHB) from the consequences of radiation exposure. This is a departure from previous regulatory frameworks which were concerned only with protecting man. The implementation of these new standards has started an ongoing discussion...
Radiation damage caused by fission fragments to metal surfaces is an important research topic. Thin titanium foils were irradiated with a continuous wave beam of 132 MeV ¹³²Xe+²⁹ at the current intensity of 2 pnA. Pre- and post-irradiated surface topologies were investigated using atomic force microscopy and the observed defects...
Portions of Yellowstone Lake sit on top of a vigorous but not well understood hydrothermal system situated in a region of intense geologic and environmental forcings. A heat flow study conducted over the Stevenson Island Vent Field (SIVF), a vent field at the bottom of Yellowstone Lake underlain by an...
Frontier research of non-aqueous actinide clusters is discussed. Since the inception of the uranyl peroxide clusters over the last decade, they have only been synthesized and characterized as solid crystals and in aqueous solution. This thesis provides thorough characterization of aqueous uranyl clusters and the first demonstration of uranyl cluster...
Electrical energy storage devices are currently the main limiting factor in many electrical devices and with the increasing demands placed on electrical power over fossil fuels, high energy density materials are essential. Previous research by Huang et al. on bulk (1-x)Bi(Zn₁/₂Ti₁/₂)O₃-xABO₃ solid solution systems led to the discovery of an...
Uranium is the most common radionuclide that found in the nature. It is a radionuclide with a very low specific activity. There is limited data on plan uptake of uranium. This research was to determine the plant uptake of uranium, calculate the concentration ratio, and estimate the dose from eating...
The urban hydrology and hydraulics program, US EPA SWMM 5, has been coupled with a compartment model of a wastewater treatment plant (WWTP) in the system dynamics software, STELLA, to simulate the radiocesium pathway from urban catchment to the wastewater treatment sludge. Two literature case studies were re-examined. Firstly, a...
A system for radiological dosimetry for nonhuman biota developed by International Commission on Radiological Protection (ICRP) relies on calculations that utilize the Monte Carlo simulations of simple, ellipsoidal geometries with internal radioactivity distributed homogeneously throughout. In this manner it is quick and easy to estimate whole-body dose rates to biota....
Radioxenon detection is a technique used to monitor nuclear explosion and verify the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Because of an ultra-low concentration of radioxenon at radioxenon monitoring stations, radioxenon detection systems must have high sensitivity. This sensitivity is measured in terms of detector's minimum detectable concentration (MDC). It is required...
The development of micro total analysis systems (µTAS), also called “lab-on-a-chip”, or microfluidic analysis systems, is presented in this dissertation. Various research areas, covering subjects from magnetic particles synthesis to novel microchip fabrication techniques, are explored to develop a lab-on-a-chip system capable of performing magnetic bead-based bioassays. These devices are...
Greenhouse studies were conducted to determine interception, absorption, and
translocation values for foliar applied ³⁶Cl. Foliar interception and uptake of contaminated irrigation water by crops is a major pathway for the transport of radionuclides to human beings in scenarios relevant to the waste disposal community. Performance assessments of many repositories...
The purpose of this study was to better understand the perceptions of employers and graduates regarding the applied baccalaureate degree when conferred by community colleges. By better understanding the perceptions of employers and graduates, community colleges considering offering applied baccalaureate degrees will have some context within which to begin communicating...
Uranyl peroxide clusters are the newest family of polyoxometalates, discovered in 2015. Although this family is new, over 70 topologies have been reported. However, we lack the fundamental understanding of assembly mechanisms, particularly the role of the alkali countercations. Here, we use a wide range of solution and solid-state characterization...
The advent of supercritical CO2 as a new heat-exchange medium has seen strong interest from the power industry and the energy research field recently. It is advan- tageous in comparison with other heat-exchange cycles, as it can be operated safely at much higher temperatures and pressures, thus increasing the thermal...
The total kinetic energy (TKE) in the fast neutron induced fission of 237Np was measured for neutron energies from En = 2.6 – 45.7 MeV at the LANSCE- WNR facility. The postTKE release decreases non-linearly with increasing incident neutron energy and can be represented as TKE(MeV) = (169.365 ± 1.551)...
The synthesis of superheavy element evaporation residues is described by the product of the capture cross section, fusion probability, and survival probability. Capture cross sections are moderately well known. The fusion probability is the least known with many uncertainties. The formalism for the survival probability is known, but the parameters...
The yields of 235 projectile-like and target-like fragments from the interaction of ¹³⁶Xe with a thick target of ²⁰⁸Pb at a center-of-mass energy, E[subscript cm], of 450 MeV were measured using γ-γ-γ coincidence data from Gammasphere and off-line γ-ray spectroscopy. The results give an expansive picture of the production cross...
A unique tumor targeted method, which may be able to deliver a molecule to the surface of a tumor cell using the pH gradient between hypoxic tumor cells and normal tissue has recently been developed. Since solid tumors have been found to have a lower extra cellular pH compared to...
Decon Gel 1101, is an uncomplicated, low odor, peelable polymer hydrogel for
use with radiological decontamination, manufactured by Cellular Bioengineer Inc. The
gel allows for single or multiple material applications to contaminated surfaces. As the
gel dries it binds the contaminant by encapsulating and lifting the contaminant into the
gel....
Mathematical modeling plays a pivotal role in understanding the mechanism of radiation-induced cellular effects, and also in quantifying the radiation risk to the cell. However, there are still compelling challenges facing the conventional modeling in radiobiology, such as lacking a generalized theory structure of quantifying target effect and non-target effect...
To quantify the relative activity contributions of beta emitters in mixed emission source spectra, the triple-layer phoswich detector was modeled to generate beta energy absorption spectra from mixed beta sources. These mixed sources include four pure beta emitters (C-14, Tc-99, Sr-90, and Y-90). Monte Carlo N-Particle (MCNP) computer code was...