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Past Research Projects

Conversion of common DSP minerals into 2:1-type clay minerals
Highly alkaline iron, aluminum, and titanium-rich tailings and refining wastes are the abundant end-products of the bauxite mining and aluminum refining industries. Worldwide, estimates of these bauxite residue stockpiles exceed 3 billion tons, with approximately 130 million tons produced every year. In the current research, we studied the synthesis of feldspathoids and their subsequent dissolution and mineral transformation. A synthetic mixture of sodalite/cancrinite was designed to be similar to the desilication products (DSP) produced during the Bayer process. These DSP materials were then transformed using a simple process to useful materials for soil amendment. (Funding: anonymous aluminum refiner)

Technetium Local Structure and Chemistry in Low Activity Waste Glass
We will obtain first-of-a-kind chemical structure determination of poorly understood, environmentally relevant technetium compounds.  Through the investigation of model alkali oxide 99Tc compounds and 99Tc-containing oxide glasses we intend to provide key data on glass structure around 99Tc , the stability of the waste glass, and its corrosion in water. There are several known polymorphs of Tc-oxide and the transformation between these phases will be examined. Search algorithms will be used to identify additional Tc-oxide phases. This work provides much needed data for the improvement of performance assessment models of Tc release in waste repositories.  (Partners:  PNNL, EMSL, LBNL, ORNL; Funding: DOE-ORP)
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Concentrated pertechnic acid

Understanding the fundamental science governing the development and performance of nuclear waste glasses
The goal of this Integrated Research Program is to supply actionable information to DOE to reduce costs and risks associated with nuclear waste vitrification. Primary information will be compositional dependence and glass chemistry effects on undesirable processing outcomes such as low waste loading, crystal formation, technetium volatility, and salt formation. (Partners:  Rutgers, University of North Texas, PNNL; Funding DOE-NE with DOE-EM)
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ZnS scintillator for high resolution X-ray imaging at 9 keV
Rapid integrated circuit (IC) inspection using x-ray microscopy requires novel X-ray scintillating materials with high efficiency and high spatial resolution. Current scintillator materials, such as Cesium Iodide (CsI), suffer from a trade-off between efficiency and spatial resolution. Novel materials which can be produced with improved brightness and decreased afterglow are necessary to address the stringent requirements of fast, high resolution X-ray microscopy. (Partners:  CeraNova, WSU Center for Materials Research; Funding: DOD-DMEA
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Apatite and sodalite based glass-bonded waste forms for immobilization of 129I and mixed halide radioactive wastes
We will develop chemically durable glass-bonded ceramic waste forms for immobilization of 129I and mixed halide wastes with focus on: (i) low-temperature synthesis (<200°C) of ceramic minerals and (ii) design of glass compositions with high chemical durability and good sintering ability at temperatures <800°C . Calcium phosphate (CaP) apatite [Ca5(PO4)3X] and sodalite [Na8(AlSiO4)6X2], containing halides (X = Cl, I) will be synthesized at low temperatures using various solution-based synthesis routes to prevent halide volatility, and these minerals will further be consolidated to monolithic waste forms using borosilicate (for sodalite) and phosphate (for CaP-apatite) glass-binders.   (Partners:  Rutgers, PNNL; Funding: DOE-NEUP)
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Understanding influence of thermal history and glass chemistry on kinetics of phase separation and crystallization in borosilicate glass-ceramic waste forms for aqueous reprocessed high level waste
We will develop a fundamental and transformative understanding of the crystallization mechanisms in complex glass-ceramic high level waste (HLW) wasteforms. This understanding will underpin the maturation of glass ceramic manufacture, by linking process variables to molecular scale mechanisms, enabling reliable production of wasteforms to the desired specification. (Partners:  PNNL, Rutgers, University of Sheffield, Warwick University; Funding DOE-NEUP)
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Advanced models for nondestructive evaluation of aging nuclear power plant cables
The objectives of this project are (i) develop advanced, validated models relating microstructural and chemical changes, due to thermal exposure, radiation exposure and water immersion, in cable insulation polymers to observable changes in dielectric, terahertz (THz) and infrared (IR) frequency spectra, (ii) identify the frequencies which most sensitively indicate microstructural and chemical changes in these polymers, and (iii) develop advanced, validated models of the response of novel cable nondestructive evaluation methods; capacitive, THz and infrared, to cable aging as a function of thermal, radiation and/or water exposure. (Partners: ISU, PNNL; Funding DOE-NEUP)
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Use of Micro- and Meso-scale Magnetic Characterization Methods to Study Degradation of Reactor Structural Material
We will integrate microstructural metrology, micro-magnetic measurements, and meso-scale phase field modeling to develop advanced tools and techniques that can extract semi-quantitative diagnostic and interpretive information about the state of microstructural damage in a material based on magnetic signature data alone. Improved diagnostic information about materials degradation will greatly enhance reactor safety by reducing uncertainty in assigning safety margins for materials currently in service and for new materials currently in development. This technology has potential for maturation into real-time, in-situ monitoring capability.  (Partners:  PNNL; Funding: DOE-NEUP)

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MFM image of Poly Fe