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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.
A. S. Ware, D. A. Spong, L. A. Berry, S. P. Hirshman, J. F. Lyon
Fusion Science and Technology | Volume 50 | Number 2 | August 2006 | Pages 236-244
Technical Paper | Stellarators | doi.org/10.13182/FST06-A1241
Articles are hosted by Taylor and Francis Online.
This work examines bootstrap current in quasi-symmetric stellarators with a focus on the impact of bootstrap current on the equilibrium properties of stellarator configurations. In the design of the Quasi-Poloidal Stellarator (QPS), a code was used to predict the bootstrap current based on a calculation in an asymptotically collisionless limit. This calculation is believed to be a good approximation of the bootstrap current for low-collisionality plasmas but is expected to be higher than the actual bootstrap current for more collisional plasmas. A fluid moments approach has been developed to self-consistently calculate viscosities and neoclassical transport coefficients. The viscosities and transport coefficients can be used to calculate the bootstrap current for arbitrary collisionality and magnetic geometry. The bootstrap current calculations from the two codes were done for low-density, electron cyclotron-heated (ECH) plasmas and high-density, ion cyclotron-heated (ICH) plasmas for a range of configurations, and provide a benchmark for the moments code and a test of the range of validity of the collisionless code. In the configurations examined here, namely, QPS, the National Compact Stellarator Experiment, the Helically Symmetric Experiment, the Large Helical Device, and the Wendelstein-7X Stellarator, the bootstrap currents predicted from the two codes agree qualitatively for both ICH and ECH profiles.