IN-CORE TRITIUM UPTAKE BY GRAPHITE IN THE FLUORIDE-SALT COOLED HIGH TEMPERATURE REACTOR (FHR)

Scarlat Photo
SPEAKER:
DR. RALUCA O. SCARLAT

ASSISTANT PROFESSOR

DEPARTMENT OF ENGINEERING PHYSICS

UNIVERSITY OF WISCONSIN MADISON

DATE/TIME:
FRI, 04/21/2017 - 4:00PM TO 5:00PM
LOCATION:
3110 ETCHEVERRY HALL
Spring 2017 Colloquium Series
Abstract:

One of the key technological challenges for Fluoride-Salt-Cooled High Temperature Reactors (FHRs) is tritium management. Tritium is produced by neutron activation of the lithium-6 and beryllium-9 isotopes that are constituents of the 2LiF-BeF2 molten salt (flibe) primary coolant. The FHR fuel elements provide a high surface area of removable graphite, which may serve as an effective tritium sink for the tritium. In order to develop a predictive model for the transport of tritium from molten flibe into graphite, the following phenomena need to be characterized: chemical speciation and mass transport in the flibe melt, transport across the salt-graphite interface, transport and reversible chemical trapping within the graphite, the effect of the chemical and physical interaction between flibe and graphite on tritium transport, and the effect of neutron irradiation on graphite. This talk will provide an overview of studies in support of the development of predictive time-dependent models for the uptake of tritium in an FHR core.

About the Speaker:

Raluca Scarlat is an assistant professor at UW Madison in the Department of Nuclear Engineering and Engineering Physics. She has a Ph.D. in nuclear engineering from UC Berkeley, and a B.S. in chemical and biomolecular engineering from Cornell University. Prior to her doctoral studies she has worked for GE and ExxonMobil. In 2011, she advised for Hitachi-GE, in Japan, on post-Fukushima changes to severe accident guidelines for the Japanese fleet of reactors. In her current work she studies thermal-hydraulics, chemistry and mass transport in molten fluoride salts. She has published articles in Nuclear Engineering and Design, Nuclear Instruments and Methods, Journal of Engineering for Gas Turbines and Power, and Progress in Nuclear Energy. Her research interests are in the area of heat and mass transport, thermal-hydraulics, nuclear reactor safety and design, and engineering ethics.

Magnetic Particle Imaging as a Deep-Penetrating, Quantitative, Sensitive Molecular and Cellular Imaging Method with 100-nM Sensitivity

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SPEAKER:
PROFESSOR STEVEN CONOLLY

M. COOK ENDOWED CHAIR

BIOENGINEERING AND EECS

UNIVERSITY OF CALIFORNIA, BERKELEY

DATE/TIME:
MON, 04/17/2017 - 4:00PM TO 5:00PM
LOCATION:
3105 ETCHEVERRY HALL
Spring 2017 Colloquium Series
Abstract:

Magnetic Particle Imaging (MPI) is a noninvasive biomedical imaging modality that shows great promise for Molecular and Cellular Imaging. MPI is in the earliest stages of development by roughly two-dozen labs worldwide, mostly in Germany. Prof. Conolly’s lab at UC Berkeley has designed and built all the MPI scanners now in North America. Stanford has purchased the first preclinical MPI scanner produced by our startup company (Magnetic Insight, Alameda CA).

MPI’s physics advantages could usher completely noninvasive alternatives to tracer studies that currently must be performed with radioactive nuclear medicine techniques, such as
• Lung perfusion imaging to supplant Tc99m-MAA Ventilation-Perfusion studies, which subjects patients to substantial radiation dose.
• Capillary-level blood volume and perfusion using longcirculating SPIOs, which could supplant radioactive studies of brain perfusion following stroke
• MPI Cancer imaging MPI may soon provide a noninvasive screening alternative to X-ray mammography. We are also collaborating with Immunotherapy expert, Dr. Larry Fong at UCSF to track immunotherapies to tumors.
• MPI molecular & cellular imaging with cell binding and cell viability in vivo.

MPI relies on completely different physics from our conventional imaging modalities: MRI, CT, X-ray, ultrasound, and nuclear medicine. MPI offers extraordinary contrast, because human tissues produce zero MPI signal and these tissues are magnetically transparent. Moreover, the induced signal from MPI tracers, superparamagnetic iron oxide (SPIO) nanoparticles, is so strong that our homebuilt Berkeley scanner shows ~100 nM [Fe] with quantitative, positive contrast. The SPIO tracers are considered safe for human use even at 2 mM [Fe], and some are already FDA or EU safety approved. SPIO tracers are thought to be safer for chronic kidney disease (CKD) patients than current contrast agents.

The Conolly lab focuses on developing the hardware, pulse sequences, and image reconstruction algorithms for MPI. The lab has also recently performed many of the world's first MPI biomedical applications, including quantitative cell tracking, shown in the Figure above, where 3 million pre-labeled stem cells were injected into the tail vein of a rat. These cells quickly became trapped in the lung capillaries (seen on Day 1), and then the cells slowly are excreted through the liver and spleen (seen on Day 12). No other imaging modality can match this image quality in the lung; indeed, MPI cell tracking has the highest sensitivity of positive contrast, whole-animal imaging techniques.
About the Speaker:

With over 25 years of medical imaging hardware, systems, and image reconstruction expertise, Steven Conolly has developed a deep and broad knowledge of scanner physics, design, and construction. By working closely with MDs at Stanford and UCSF, he has developed appreciation for biomedical applications of innovative biomedical imaging scanners. The Conolly lab now emphasizes innovative hardware for important clinical and preclinical applications. Dr. Conolly oversaw the design and construction of 3 pre-polarized MRI scanners at Stanford University and 4 Magnetic Particle Imaging (MPI) scanners at UC Berkeley. MPI is a new imaging modality, which is ideal for sensitive and quantitative detection of iron oxide tracers placed on cellular therapies. The Conolly lab at UC Berkeley has built the world's highest spatial resolution MPI scanner (with a 7 T/m gradient selection field) and the only projection MPI scanner in the world. In addition, the lab has built the only 3D Projection-Reconstruction MPI scanner in existence.

Steven Conolly has nearly 30 US Patents in various stages of approval; GE, Siemens, and Philips have licensed more than half of my patents. In 2004, Stanford named him an Outstanding Inventor for his patents, one of only 24 people in the history of Stanford to be given this honor. At UC Berkeley, he has held several important administrative roles, including Chair of the Graduate Group in Bioengineering, which is joint program between UCSF and UC Berkeley.  Dr. Conolly received his Ph.D. in Electrical Engineering from Stanford University.

Controlled Synthesis of Actinide Materials: Science Underpinning Development of Advanced Nuclear Fuels

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SPEAKER:
DR. STEFAN MINASIAN

LAWRENCE BERKELEY NATIONAL LABORATORY

DATE/TIME:
WED, 04/12/2017 - 4:00PM TO 5:00PM
LOCATION:
3105 ETCHEVERRY HALL
Spring 2017 Colloquium Series
Abstract:

The design of advanced nuclear fuels poses considerable challenges in terms of understanding the physical phenomena occurring in complex systems under extreme conditions, with length scales from the atomic to the macroscopic, and over time scales from femtoseconds to years. After irradiation, fuels exhibit a complex nano- and micro-scale structure with multiple chemical components, oxidation states, and crystal phases. Controlling this structure may reduce the potential for failure of nuclear fuels by providing pathways for fission gas release, enhancing radiation tolerance, and improving heat transfer capabilities. Improvements in the performance of advanced nuclear fuels will require new strategies for actinide nanomaterials synthesis, coupled with an improved understanding of how nanoscale structure is both an advantage and a limitation to fuel designs.

This presentation will describe our recent efforts to use actinide synthesis, synchrotron spectroscopy, and first-principles calculations to develop a basis for the rational design of advanced nuclear fuels. Work began by developing an intuitive theoretical framework for relating actinide electronic structure and physical properties. This included spectroscopic analyses of the actinyl ions, which are perhaps the most ubiquitous high-valent molecules in nuclear chemistry. Our approach also included extended structures such as actinide–aluminum alloys, which are relevant to strategies for stabilizing delta-plutonium. These molecular-level insights were used to invent new synthetic methodologies that provide control over the mechanisms of formation, chemical reactivities, and physical properties of actinide materials. The discussion will also include preliminary results demonstrating how nanoscale structure can impact the physical properties most relevant to fuel performance.

About the Speaker:

Dr. Stefan Minasian received a B.A. in Chemistry from Reed College in 2002 with Prof. Margaret Geselbracht before coming to the University of California, Berkeley as a graduate student in the Department of Chemistry with Prof. John Arnold. His interest in nuclear chemistry began while developing syntheses for the first molecular compounds to exhibit unsupported metal–metal bonds between uranium and group 13 elements (e.g., aluminum and gallium). These discoveries ignited new theoretical discussions regarding heavy element structure–property relationships, in particular the relative roles of the 5f and 6d orbitals in controlling physical phenomena. Following completion of his Ph.D. in 2010, Dr. Minasian joined research groups at Los Alamos National Laboratory (LANL) and Lawrence Berkeley National Laboratory (LBNL), and held two concurrent Seaborg Fellowships in the Seaborg Institute at LANL and the Glenn T. Seaborg Center at LBNL. During this joint appointment, he led a collaborative effort to develop direct spectroscopic probes of actinide bonding and was at the forefront of a growing movement in nuclear chemistry that has changed how scientists formulate models of electronic structure. He became a Staff Scientist in the Heavy Elements Chemistry group in the Chemical Sciences Division at LBNL in 2014, where his current research occurs at the interface of materials design, inorganic spectroscopy, and theory. Controlling the chemical and physical properties of the poorly-understood transuranium elements (e.g., neptunium and plutonium) is of particular concern given their central role in scientific and technological applications for actinides in nuclear fuels, separations, and waste forms. The collaborative effort brings together scientists at multiple universities and DOE National Laboratories, and leverages access to cutting-edge instrumentation at several user facilities including the Advanced Light Source, Molecular Foundry, Stanford Synchrotron Radiation Lightsource, and Canadian Light Source.

Heavy elements in nature: from radionuclide decontamination to targeted radiotherapy

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SPEAKER:
DR. REBECCA ABERGEL

STAFF SCIENTIST AND CAREER DEVELOPMENT & DIVERSITY OFFICER, CHEMICAL SCIENCES DIVISION

DEPUTY DIRECTOR, INSTITUTE FOR RESILIENT COMMUNITIES

LAWRENCE BERKELEY NATIONAL LABORATORY

DATE/TIME:
TUES, 04/11/2017 - 4:00PM TO 5:00PM
LOCATION:
3105 ETCHEVERRY HALL
Spring 2017 Colloquium Series
Abstract:

Recent events have called attention to the persistent possibilities of environmental and human contamination with radioisotopes such as lanthanide fission products and actinides. In parallel, a few actinide isotopes have recently emerged as promising short-lived radionuclides for targeted alpha-particle therapy. However, limited research has been directed to the characterization of f-element chemistry in biologically relevant systems. A combination of biochemical and spectroscopic approaches on both in vitro and in vivo systems is currently used to study the selective binding and recognition of lanthanides and actinides by natural and synthetic platforms. Studying the biokinetics, photophysics, solution thermodynamics, and structural features of f-element complexes has important implications for the development of new decontamination agents and separation strategies, but also for the design of future targeted imaging and radio-therapeutic constructs.

About the Speaker:

Dr. Abergel’s research program is dedicated to investigating the coordination biochemistry of heavy and f-elements, with therapeutic and environmental applications such as chelation and bioremediation of toxic metals released in industrial processes, engineering of antimicrobial strategies targeting metal-acquisition systems, and design of advanced alpha-immuno theranostic agents. She leads a large collaborative effort on the development of new drug products for the treatment of populations contaminated with radionuclides. One of these products was granted an Investigational New Drug status from the U.S. Food and Drug Administration in 2014. In addition, she has been actively involved in the new Lawrence Berkeley National Laboratory Initiative for Resilient Communities, the radiological component of which was sparked by the aftermath of the 2011 Fukushima Daiichi accident.

Dr. Abergel was raised in France and graduated from the École Normale Supérieure of Paris in 2002. She conducted her graduate studies in inorganic chemistry at UC Berkeley, under the supervision of Professor Kenneth Raymond. Her doctoral work focused on the synthesis and characterization of siderophore analogs to probe microbial iron transport systems and design new iron chelating agents. As a joint postdoctoral researcher between the UC Berkeley Chemistry Department and the group of Professor Roland Strong at the Fred Hutchinson Cancer Research Center, she investigated the bacteriostatic function of the innate immune protein siderocalin in binding siderophores from pathogenic microorganisms such as Bacillus anthracis, for the development of new antibiotics. Dr. Abergel joined Berkeley Lab in 2009, where she currently serves as the chair of the Radioactive Drug Research Committee and is an associate editor for the International Journal of Radiation Biology and a corresponding member (USA) for Radioprotection. Dr. Abergel is the recipient of a WCC Rising Star award from the American Chemical Society (2017), an Early Career award from the U.S. Department of Energy (2014), and was selected as an Innovator under 35 – France by the MIT Technology Review in 2014. She also received a Junior Faculty NCRP award (2013) from the Radiation Research Society, and a Young Investigator Research Fellowship (2010) from the Cooley’s Anemia Foundation.

Phase stability of nuclear materials in extreme environments

Tracey Photo
SPEAKER:
DR. CAMERON L. TRACY

DEPARTMENT OF GEOLOGICAL SCIENCES

CENTER FOR INTERNATIONAL SECURITY AND COOPERATION

STANDFORD UNIVERSITY

DATE/TIME:
MON, 04/10/2017 - 4:00PM TO 5:00PM
LOCATION:
3105 ETCHEVERRY HALL
Spring 2017 Colloquium Series
Abstract:

Throughout the nuclear fuel cycle materials are subjected to extreme conditions. Nuclear fission and decay yield high temperatures in fuels and wastes, while mechanical stresses are encountered during fuel swelling and in the geological environments associated with actinide extraction and disposal. Irradiation with fission products and alpha particles causes the dense excitation of electrons, modifying chemical bonding. Under these conditions, which are often encountered simultaneously, many materials degrade. Thus, a central challenge in advanced fuel cycle concepts is the development of materials that maintain their atomic structures, and therefore their critocal properties, under extreme conditions.

This talk describes a number of experimental studies in which extreme fuel cycle conditions are simulated in the laboratory. By coupling laser and resistive heating, diamond anvil pressure cells, and heavy ion accelerators, the structural and chemical behavior of nuclear materials in fuel cycle environments can be observed and elucidated. Recent accomplishments include the demonstration of irradiation‐induced redox reactions in uranium oxides and the atomic‐scale nature of nuclear waste form disordering by temperature, pressure, and irradiation.

While this approach is useful for the design of materials that are resistant to modification by extreme environments, such conditions can also be harnessed to produce new materials not accessible through conventional processing techniques. For example, the irradiation of lanthanide sesquioxides with heavy ions yields previously unreported metastable phases, and exposure of multicomponent equiatomic alloys to extreme mechanical stresses yields new, high‐hardness phases.

About the Speaker:

Dr. Cameron L. Tracy is a postdoctoral fellow in the Department of Geological Sciences and the Center for International Security and Cooperation at Stanford University. He received his PhD in materials science and engineering from the University of Michigan, and his BS from the University of California, Davis. His PhD work was supported by a National Science Foundation Graduate Research Fellowship, and in 2015 he received a Young Scientist Award from the European Materials Research Society. Cameron’s research addresses the behavior of nuclear materials, including complex oxides and multicomponent alloys, in extreme temperature, pressure, and radiation environments. He previously worked as a research assistant at Los Alamos National Laboratory.

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