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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.
K. Tanaka, K. Kawahata, T. Tokuzawa, T. Akiyama, M. Yokoyama, M. Shoji, C. A. Michael, L. N. Vyacheslavov, S. Murakami, A. Wakasa, A. Mishchenko, K. Muraoka, S. Okajima, H. Takenaga, LHD Experiment Group
Fusion Science and Technology | Volume 58 | Number 1 | July-August 2010 | Pages 70-90
Chapter 3. Confinement and Transport | Special Issue on Large Helical Device (LHD) | doi.org/10.13182/FST10-A10795
Articles are hosted by Taylor and Francis Online.
Particle confinement processes are studied in detail on the Large Helical Device (LHD). Diffusion coefficients (D) and convection velocities (V) are estimated from density modulation experiments. The magnetic configuration and collisionality are widely scanned in order to investigate parameter dependences of D and V. To study the effect of the magnetic configuration, magnetic axis positions (Rax) are scanned from 3.5 to 3.9 m. This scan changes the magnetic ripples quite significantly, enabling the effects of neoclassical properties on measured values to be widely elucidated. Dependences of electron temperature (Te) and helically trapped normalized collisionality are examined using the heating power scan of neutral beam injection. It was found that generally larger (or smaller) contributions of neoclassical transport in the core region, where normalized position < 0.7, resulted in more hollow (or peaked) density profiles. The larger neoclassical contribution was found to be situated at a more outwardly shifted Rax for the same Te and for higher Te or lower h* at each Rax. However, it is to be noted that Rax = 3.5 m shows different characteristics from these trends, that is, a more peaked density profile at higher Te or lower h*. The edge ( > 0.7) diffusion and convection are dominated by anomalous processes. Measured edge turbulence shows a possible linkage.