POSTPONED: Dalton Seminar Series: Small scale production of high-purity plutonium metal
|Starts:||12:15 14 Sep 2017|
|Ends:||13:15 14 Sep 2017|
|What is it:||Seminar|
|Organiser:||Dalton Nuclear Institute|
|Who is it for:||University staff, Alumni, Current University students|
Unfortunately this seminar has been postponed.
Small-scale scientific experiments require high-purity, low activity plutonium metal that is formed into components with nanoscale surface finishes and micron-scale surface features. We have developed a process for winning micro-ingots (~300 mg) of alpha-phase Pu metal from plutonium oxide. This process involves chemical removal of Am-241, followed by a fluorination process. The metal is formed via a metallothermic reaction in an induction furnace. Optical metallography of the first Pu micro-ingots indicated a two-phase mixture, but the density, as measured with an immersion technique, was 19.3 ± 0.4 g/cm3, indicating that the material had to be nearly all in the ?-Pu phase (theoretical density = 19.84 g/cm3; typical density of electrorefined, as cast material = 19.65 g/cm3). Extensive characterization of this material, including optical microscopy, Auger spectroscopy, mass spectrometry, x-?ray diffraction, scanning electron microscopy, transmission electron microscopy, and electron microprobe, revealed that a few atomic percent of nickel contamination resulted in a eutectoid microstructure. The two phases are ?-Pu and a eutectoid mixture of PuNix and ?-Pu. The nickel contamination entered the process during the fluorination step, which involves high-temperature HF gas in nickel tubes. I will describe our efforts to minimize nickel contamination, resulting in recent batches of this Pu metal that show significantly decreased impurity concentrations.
I will also present an overview of the Materials Science Division at Lawrence Livermore National Laboratory, highlighting our capabilities for processing, handling, and characterizing small-scale actinide samples.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-?AC52-?07NA27344. LLNL-ABS-736527
Organisation: Laurence Livermore National Laboratory
Biography: Kerri Blobaum is a materials scientist in the Materials Science Division at Lawrence Livermore National Laboratory. She received a Bachelor of Arts degree in chemistry and mathematics from Wartburg College, and a Master of Science degree in materials science from the University of Wisconsin-Madison. Kerri completed her PhD in materials science at The Johns Hopkins University, where she characterized phase transformations in reactive multilayer foils. As a postdoc, she continued to study phase transformations at Lawrence Livermore National Laboratory, but the materials were plutonium alloys. As a materials scientist at LLNL, Kerri has worked on a variety of actinide metallurgy projects. She is currently the Group Leader of the Materials Characterization Group and a Deputy Program Leader.
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