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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.
Y. Takeiri, S. Kubo, T. Shimozuma, M. Yokoyama, M. Osakabe, K. Ikeda, K. Tsumori, Y. Oka, K. Nagaoka, Y. Yoshimura, K. Ida, H. Funaba, S. Murakami, K. Tanaka, B. J. Peterson, I. Yamada, N. Ohyabu, K. Ohkubo, O. Kaneko, A. Komori, LHD Experimental Group
Fusion Science and Technology | Volume 46 | Number 1 | July 2004 | Pages 106-114
Technical Paper | Stellarators | doi.org/10.13182/FST04-A546
Articles are hosted by Taylor and Francis Online.
The electron internal transport barrier (ITB) is formed with centrally focused electron cyclotron resonance heating superposed on plasmas heated by neutral beam injection in the Large Helical Device. The electron transport is investigated for the electron ITB plasmas observed in various magnetic axis positions of Rax = 3.6, 3.75, and 3.9 m, and it turns out that the core electron transport is reduced with suppression of the anomalous transport in all three magnetic axis positions. In the theoretical calculations, positive radial electric fields are generated in the improved transport region, implying that the electron ITB formation is correlated with the neoclassical electron root. At an outer-shifted configuration of Rax = 3.9 m, where the helical ripple is large, the thermal diffusivity is decreased with decreasing collisionality, suggesting the reduction of the ripple transport by the radial electric field. The temperature and density conditions for the ITB formation are consistent with the theoretical density dependence of the transition temperature to the neoclassical electron root from the ion root.