Hot isostatically pressed tailored hollandite waste forms were used to demonstrate the immobilization of Cs and Sr are separable from spent nuclear fuel, as well as Ba and Rb. Four hollandite formulations were investigated, two samples with ∼12 wt% waste loading (on an oxide basis) and two with ∼18 wt% waste loading. Two of the samples were Al‐substituted and the other two contained Mg. The hollandite in the Al‐substituted samples contained all the waste cations, as designed, but this was not the case in the Mg‐substituted samples. The hollandite in the Mg‐substituted samples did not contain all the waste cations, with ∼50% of the Sr forming SrTiO3 as a secondary phase. This resulted in waste forms that were not as durable, with respect to Cs, as their Al counterparts. The formation of SrTiO3 had little effect on the Sr release rates and was not detrimental to the Mg‐substituted hollandite waste form. For the Al‐substituted samples, the MCC‐1 normalized release rates were <0.06 g·(m2·day)−1 at 0–28 days for all elements, while the Cs release rates remained at 2.0 g·(m2·day)−1 at 0–28 days for the Mg‐substituted samples.
Defence Materials Technology Centre, VIC 3122, AustraliaColloidal processing of the Ultra-High Temperature Ceramic (UHTC) zirconium diboride (ZrB 2 ) to develop nearÀnet-shaping techniques has been investigated. The use of the colloidal processing technique produces higher particle packing that ultimately enables achieving greater densification at lower temperatures and pressures, even pressureless sintering. ZrB 2 suspension formulations have been optimized in terms of rheological behavior. Suspensions were shaped into green bodies (63% relative density) using slip casting. The densification was carried out at 1900°C, 2000°C, and 2100°C, using both hot pressing at 40 MPa and pressureless sintering. The colloidally processed materials were compared with materials prepared by a conventional dry processing route (cold pressed at 50 MPa) and subjected to the same densification procedures. Sintered densities for samples produced by the colloidal route are higher than produced by the dry route (up to 99.5% relative density by hot pressing), even when pressureless sintering is performed (more than 90% relative density). The promising results are considered as a starting point for the fabrication of complex-shaped components that can be densified at lower sintering temperatures without pressure. W.-C. Wei-contributing editor Manuscript No. 31878.
Family, school, and community contexts each link to secondary school enrollment, yet these factors have been comparatively examined only in limited ways. A holistic examination of contextual factors will be particularly important for engineering where college enrollment patterns vary by demographics. To begin explaining patterns of engineering college-going at different high schools across the Commonwealth of Virginia, we answered the following research questions: Within a single school system and from a socializer's perspective, what outcome expectations and environmental factors influence students' engineering-related postsecondary educational plans? How are these factors the same and different between high schools within a school district? Using a single-case-study approach and in-depth interviews with socializers (teachers, administrators, and counselors), we examined similarities and differences in outcome expectations and environmental factors at three high schools within a single school district. By integrating the results regarding outcome expectations and environmental factors, three important findings emerged: (1) relationships between outcome expectations and environmental factors vary across schools within the same system, (2) proximity to a postsecondary institution is not just about physical distance, and (3) messaging regarding career pathways matters. Each of these has practical implications but can also set the foundation for future research.
Hot isostatically pressed (HIPed) glass-ceramics for the immobilization of uranium-rich intermediate-level wastes and Hanford K-basin sludges were designed. These were based on pyrochlore-structured Ca (1-x) U (1+y) Ti 2 O 7 in glass, together with minor crystalline phases. Detailed microstructural, diffraction and spectroscopic characterization of selected glass-ceramic samples has been performed, and chemical durability is adequate, as measured by both MCC-1 and PCT-B leach tests.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.