B.S. SUNY Oswego

Master's Program in Health Physics

Comparison of alpha spectroscopy methods

The goal of this research is to streamline the sample preparation procedure for alpha spectroscopy. Three methods used are electrodeposition (Kressin method), microprecipitation (cerium-fluoride method), and evaporation (drop method). Different matrices, such as water, soil, and air filters will be prepared and analyzed using alpha spectroscopy. Actinides will be the main elements of concern for this project, namely tracers of ²⁴²Pu and ²⁴³Am will be used.  Each method will be evaluated quantitatively and compared against one another.  Parameters such as time and cost efficiency will be evaluated to determine the most productive method for preparing samples for alpha spectroscopy. The ideal sample will be a monatomic layer of the actinide to be evaluated with as little other contaminants as possible to prevent self-attenuation.

Lisa Mullen

B.S. Michigan State University

Ph.D. Student, Nuclear Engineering, Massachusetts Institute of Technology

Effect of bacteria on actinide speciation

Bacteria are present ubiquitously throughout the environment, thus it is important to understand how bacteria can affect the speciation and transport of uranium in the environment. Current research involves the study of bacterial effects on the oxidation-reduction state of uranium. S. oneidensis , a multiple metal-reducing bacteria, will reduce U(VI) to U(IV). The tetravalent uranium product (UO₂) is insoluble, and the reaction acts to immobilize any soluble uranium. This interaction may eventually prove to be beneficial for site remediation of uranium contaminated soil. The oxidation of uranium from U(IV) to U(VI) may be undesirable from an environmental standpoint, however, it is still necessary to understand to what extent (if any) bacteria are capable of uranium oxidation. Other work involves the investigation of the iron and manganese oxidizing bacterium Leptothrix discophora and its effects on uranium. Manganese oxides of biological origin could be even more reactive with uranium than traditional manganese oxide minerals and may lead to both sorption of soluble uranium as well as dissolution of solid UO₂.

Julie Gostic

M.S. Radiological Sciences and Protection, University of Massachusetts,
Lowell

B.S. Physics, Biology, College of Charleston

Ph.D. Student, Radiochemistry Program

Development of rapid radiochemical separation and analysis techniques

Radioanalysis has been used for many years in the fields of environmental restoration/ assessment and nuclear materials processing. The complexity of this process is compounded when multiple radionuclides and/or interfering species are present in a given system. For example, a sample from a nuclear waste stream/effluent may contain several different alpha, beta and gamma emitters. Most alpha emitters have energies in the range of 4-6 MeV. Even with state-of-the-art spectroscopic detection systems, it can be difficult to resolve the energies of the isotopic contributors. In addition, the beta and gamma response can create an increased continuum which can diminish the resolution of the spectral data. Traditionally, great lengths have been taken to separate out the radionuclides of interest prior to sample measurement. For the laboratory setting, this process is time consuming and tedious, but critical for quality environmental surveillance programs. With the nation’s increased focus on emergency response and preparedness, the development of more rapid analysis techniques that have the potential for automation must be considered for large scale sampling. My research goal is to critically evaluate the fundamental radiochemistry of environmental samples and to develop more rapid/automated analytical techniques and apply those findings to better dispersion/dose models, emergency response protocols, and attribution sciences efforts.

Craig Bias, Lt. Col, USAF

M.S. Health Physics,
Colorado State University

M.S. Environmental Engineering, Old Dominion University

B.S.Physics/ Astrophysics, Michigan State University

Ph.D. Student, Radiochemistry Program

Residual radioactive materials from illicit activities such as ore enrichment, nuclear fuel reprocessing, or radioactive dispersal device detonation may be detected remotely and collected for chemical and forensic analysis. The RRaDIUS system is being developed for Department of Defense use with funding from the Defense Advanced Research Projects Agency to detect these activities. Encapsulated coatings will be applied to surfaces of interest and interrogated with optical systems remotely. Coatings consist of aqueous and organic phases to transport radionuclides from surface to coating materials and ultraviolet scintillating nanocrystals to emit light in the solar-blind region for optical detection. The optical system (bandpass filters, ultraviolet-transmitting lens, image intensifier, and multiplexer) allows remote coating interrogation to determine if retrieval is warranted and to assess potential exposures to personnel approaching the surface. Upon coating retrieval, radiochemical separations and speciation will be performed to aid forensic investigations.

Amber Wright

B.S. Chemistry   B.S. Mathematics 

University of Nevada, Las Vegas

Ph.D. Student, Radiochemistry Program

Role of anions (nitrate, pertechnetate) on the speciation of U and Pu in the tri-butylphosphate-dodecane-nitrate system

I will study speciation of U and Pu in a TBP-dodecane-nitric acid extraction system, focusing on the effect of nitrate and pertechnetate on actinide speciation. The aqueous phase will consist of uranyl or plutonium nitrate, nitric acid, and lithium nitrate. The organic phase will consist of 30% TBP (tributylphosphate) in dodecane solution, and equal volumes of the two phases will be contacted. The concentrations of metal, acid, and total nitrate and pertechnetate will be examined in each phase, as well as a spectroscopic investigation. These studies will be used to obtain data for modeling the behavior of actinides under a range of conditions germane to advanced separations. This project is aimed to meet needs stated by the AFCI in relation to the reprocessing of spent nuclear fuel.

Rich Gostic

M.S. Nuclear Engineering, Massachusetts Institute of Technology

B.S. Chemistry, College of Charlston

Ph.D. Student, Radiochemistry Program

Actinide environmental chemistry:  Solid-liquid interface and advanced NMR techniques

Understanding the behavior of plutonium and americium in the environment is usually limited to laboratory experiments carried out over relatively short time scales.  My research focus is on the behavior of particulate weapons grade plutonium (‘hot particles’) exposed to environmental conditions and the near field behavior of plutonium and americium released to the environment from the hot particle.  The experience gained and techniques developed from this research are being applied to the study of americium, neptunium and plutonium under varied environmental conditions.

The recent acquisition of a 400MHz Varian NMR, with solids capability and the low gamma accessory, by UNLV will allow for the development of techniques to study ²³⁹Pu and ²³⁵U solid state compounds.  The combination of our ability to work with the actinides and this new tool will allow us to explore the application of NMR to the study of uranium and plutonium compounds in both the sold and liquid states.  As part of my research, I will explore the potential applications of this system to the characterization of plutonium and uranium compounds.

Kiel Holliday

B.S. Chemistry

California State University, San Marcos

Ph.D. Student, Radiochemistry Program

This project will examine inert matrix fuels containing ZrO₂ and MgO for the burning of Pu. Ceramics are synthesized using a precipitation method and characterized using x-ray fluorescence (XRF), x-ray diffraction (XRD), x-ray absorption fine structure (XAFS), optical microscopy, scanning electron microscopy (SEM), microprobe, transmission electron microscopy (TEM), and thermal gravimetric analysis/dynamic scanning calorimetry (TGA/DSC). The solubility of the fuel ceramics, in reactor conditions, reprocessing conditions, and repository conditions, will be investigated in a manner to provide thermodynamic data necessary for modeling.

The fuel matrix will be optimized based on neutronic properties, repository behavior, and reprocessing characteristics. The matrix should be as neutron transparent as possible. Burnable poisons will be used to maintain constant reactivity. The matrix should also act as a suitable host form for fission products and actinides in a repository environment. Finally, the matrix should be compatible with reprocessing schemes under development in the advanced fuel cycle.

Nick Smith

B.S. Chemistry

Lake Superior State University

Ph.D. Student, Radiochemistry Program

To support the demonstration of a more proliferation-resistant fuel processing plant, techniques and instrumentation to allow the real-time, on-line determination of special nuclear material concentrations in-process must be developed.  Optical spectroscopy techniques, such as Ultraviolet and Visible Spectroscopy and Time Resolved Laser Induced Fluorescence Spectroscopy, are being evaluated to meet this need.  These techniques are commonly used in the laboratory setting for the measurement of actinide concentrations in the ranges of interest to nuclear fuel recycling. As non-nuclear techniques they show potential for use in high radiation environments. They allow direct measurement of constituent concentrations in UREX process streams.  My work focuses on determining the impact of process chemistry on the detection, quantization, and speciation of the actinides with both UV-Vis and TRLFS.  The research will evaluate the change of spectroscopic properties with actinide speciation and complexation.

Charles Yeamans

M.S. Nuclear Engineering
Massachusetts Institute of Technology

B.S. in Chemical Engineering and Nuclear Engineering
University of California, Berkeley

University of California, Department of Nuclear Engineering, Ph.D. student

Uranium dioxide reacts with ammonium bifluoride at room temperature to form ammonium uranium fluoride compounds, replacing the uranium-oxygen bond with uranium-fluorine bonds. The ammonium uranium fluoride salt system can then be used in two different processes whose products are useful to the nuclear industry.

Tetraammonium uranium (IV) octafluoride, produced in a mechanical ball mill at 25 °C from uranium dioxide and ammonium bifluoride, was heated to 800 °C in a platinum crucible under ammonia to form uranium dinitride (UN 2) and ammonium fluoride. The UN 2 produced contained less than 1.0 weight percent UO 2 impurity. The UN 2 was then denitrided by heating to 1200 °C under inert atmosphere, forming uranium mononitride (UN). The UN produced in this manner may be suitable for fuel fabrication, primarily because of low oxide and carbide impurity levels.

In addition, ammonium uranium fluorides can be decomposed to uranium tetrafluoride, which can then be reacted with oxygen to form uranium hexafluoride and uranyl fluoride. Uranyl fluoride can be recycled to the beginning of the process by reacting with hydrogen. This presents a viable alternative to the current uranium conversion process.

Professor Czerwinski is my research advisor, who supervises my Ph.D. work along with my academic advisor Professor Donald Olander at UC Berkeley.