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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.
Toshihiko Yamanishi, Mikio Enoeda, Kenji Okuno, Robert H. Sherman
Fusion Science and Technology | Volume 29 | Number 2 | March 1996 | Pages 232-243
Technical Paper | Fusion Fuel Cycle | doi.org/10.13182/FST96-A30710
Articles are hosted by Taylor and Francis Online.
A control method was proposed for the cryogenic distillation column with a feedback stream. The top and bottom flow rates of the column are adjusted for the variation of external feed composition to control product purity. The flow rate of the side stream and the power of the reboiler heater are promptly and linearly changed with the corresponding variation of external feed flow rate. Ordinary columns with no feedback stream are first-order lag systems for the case where the top flow rate is chosen as a manipulated variable. On the other hand, the column with a feedback stream is a second-order lag system even in this case. The parameter-setting method of the proportional-integral (PI) controller was proposed to predict the unstable region in the control of the column. The method can also be applied to the case where the measurement of the controlled variable is accompanied by a long time lag. However, the longer time lag requires a larger integral time, and the larger integral time brings a larger overshoot and slower damping for the controlled variable. For this case, the promptness of the control can be improved by introducing the PI derivative controller.