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Setting and stiffening of cementitious components in Cast Stone waste form for disposal of secondary wastes from the Hanford waste treatment and immobilization plant
Cast Stone is a cementitious waste form, a viable option to immobilize secondary nuclear liquid wastes generated from the Hanford Waste Treatment and Immobilization Plant. However, no study has been performed to understand the flow and stiffening behavior, which is essential to ensure proper workability and is important to safety in a nuclear waste field-scale application. X-ray diffraction, rheology, and ultrasonic wave reflection methods were used to understand the specific phase formation and stiffening of Cast Stone. Our results showed a good correlation between rheological properties of the fresh mixture and phase formation in Cast Stone. Secondary gypsum formation was observed with low concentration simulants, and the formation of gypsum was suppressed in high concentration simulants. A threshold concentration for the drastic change in stiffening was found at 1.56 M Na concentration. It was found that the stiffening of Cast Stone was strongly dependent on the concentration of simulant. Highlights: • A combination of XRD, UWR, and rheology gives a better understanding of Cast Stone. • Stiffening of Cast Stone was strongly dependent on the concentration of simulant. • A drastic change in stiffening of Cast Stone was found at 1.56 M Na concentration.
Equation of state and phase diagram of Fe-16Si alloy as a candidate component of Earth's core
The outer core of the Earth contains several weight percent of one or more unknown light elements, which may include silicon. Therefore it is critical to understand the high pressure–temperature properties and behavior of an iron–silicon alloy with a geophysically relevant composition (16 wt% silicon). We experimentally determined the melting curve, subsolidus phase diagram, and equations of state of all phases of Fe–16 wt%Si to 140 GPa, finding a conversion from the D0 3 crystal structure to a B2+hcp mixture at high pressures. The melting curve implies that 3520 K is a minimum temperature for the Earth's outer core, if it consists solely of Fe–Si alloy, and that the eutectic composition in the Fe–Si system is less than 16 wt% silicon at core–mantle boundary conditions. Comparing our new equation of state to that of iron and the density of the core, we find that for an Fe–Ni–Si outer core, 11.3±1.5 wt% silicon would be required to match the core's observed density at the core–mantle boundary. We have also performed first-principles calculations of the equations of state of Fe 3 Si with the D0 3 structure, hcp iron, and FeSi with the B2 structure using density-functional theory.
Experimental and Numerical Study of Lift-off Length and Ignition Delay of a Two-component Diesel Surrogate
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Enhancing safety of hydrogen containment components through materials testing under in-service conditions
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Revealing a role for the G subunit in mediating interactions between the nitrogenase component proteins
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Lithium sputtering from lithium-coated plasma facing components in the NSTX divertor
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Component effects on crystallization of RE-containing aluminoborosilicate glass
Lanthanide-aluminoborosilicate (LABS) glass is one option for immobilizing rare earth (RE) oxide fission products generated during reprocessing of pyroprocessed fuel. This glass system can accommodate a high loading of RE oxides and has excellent chemical durability. The present study describes efforts to model equilibrium crystallinity as a function of glass composition and temperature as well as liquidus temperature (TL) as a function of glass composition. The experimental method for determining TL was ASTM C1720-11. Typically, three crystalline phases were formed in each glass: Ce-borosilicate (Ce 3 BSi 2 O 10 ), mullite (Al 10 Si 2 O 19 ), and corundum (Al 2 O 3 ). Cerianite (CeO 2 ) was a common minor crystalline phase and Nd-silicate (Nd 2 Si 2 O 7 ) occurred in some of the glasses. In the composition region studied, TL decreased as SiO 2 and B 2 O 3 fractions increased and strongly increased with increasing fractions of RE oxides; Al 2 O 3 had a moderate effect on the TL but, as expected, it strongly affected the precipitation of Alcontaining crystals.
Non-destructive characterization of additively manufactured components with x-ray computed tomograph
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Precipitate strengthening and thermal stability in three component metallic nanolaminate thin films
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