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Fusion Science and Technology
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Glass strategy: Hanford’s enhanced waste glass program
The mission of the Department of Energy’s Office of River Protection (ORP) is to complete the safe cleanup of waste resulting from decades of nuclear weapons development. One of the most technologically challenging responsibilities is the safe disposition of approximately 56 million gallons of radioactive waste historically stored in 177 tanks at the Hanford Site in Washington state.
ORP has a clear incentive to reduce the overall mission duration and cost. One pathway is to develop and deploy innovative technical solutions that can advance baseline flow sheets toward higher efficiency operations while reducing identified risks without compromising safety. Vitrification is the baseline process that will convert both high-level and low-level radioactive waste at Hanford into a stable glass waste form for long-term storage and disposal.
Although vitrification is a mature technology, there are key areas where technology can further reduce operational risks, advance baseline processes to maximize waste throughput, and provide the underpinning to enhance operational flexibility; all steps in reducing mission duration and cost.
François Ryter, Albrecht Stäbler, Giovanni Tardini
Fusion Science and Technology | Volume 44 | Number 3 | November 2003 | Pages 618-635
Technical Paper | ASDEX Upgrade | doi.org/10.13182/FST03-A403
Articles are hosted by Taylor and Francis Online.
The studies carried out in ASDEX Upgrade on transport in conventional scenarios are presented. The well-known property of tokamak temperature profiles being resilient is investigated in and interpreted, for both ions and electrons, as due to the existence of an inverse critical gradient length below which transport is low and above which it increases. Experiments in H-mode with different heating power deposition profiles were carried out. Simulation results of a variety of H-mode plasmas with three different transport models based on the physics assumptions that include the existence of such a threshold confirm this hypothesis. However, the profiles are not extremely stiff and can significantly deviate from the critical value. Electron heat transport was investigated in various experiments using electron cyclotron heating combining steady-state and power modulation. A variation of the electron heat flux while keeping the edge flux constant allows measurement of the threshold and the properties of electron transport. These resilience properties lead to a correlation between core and edge and to a dependence of global confinement on the pedestal energy. This is quantified in the analyses of a database that yield expressions linking edge and global confinement.