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NRC issues draft EA/FONSI for Duane Arnold restart
Efforts by NextEra Energy to restart the Duane Arnold nuclear power plant as early as 2029 continue to move forward with the Nuclear Regulatory Commission's preliminary environmental assessment and determination that the restart would have no significant environmental impacts.
On Thursday, the NRC posted a draft environmental assessment and a finding of no significant impact for the Palo, Iowa, facility; the Federal Register notice was published on Monday. The Department of Energy’s Office of Energy Dominance Financing is a cooperating agency on the draft EA, as the DOE is considering providing financial assistance to the restart project.
T. E. Gebhart, S. J. Meitner, L. R. Baylor
Fusion Science and Technology | Volume 75 | Number 8 | November 2019 | Pages 759-766
Technical Paper | doi.org/10.1080/15361055.2019.1592997
Articles are hosted by Taylor and Francis Online.
Mitigation of disruption events in future high energy density tokamaks is essential for machine longevity. The creation of runaway electrons, large electromagnetic forces, and high localized heat loads during a disruption can be devastating to machine components. Shattered pellet injection is currently the most effective method of disruption mitigation. Injection of cryogenically solidified deuterium, neon, or argon (or mixtures thereof) have been shown to efficiently radiate thermal energy of the plasma so that the heat load is distributed on the walls of the machine. Pellets are formed by desublimating gas in the barrel of a pipe gun and fired using a pulse of high-pressure light gas. Current gas gun designs cannot reach sufficient pressure to dislodge pure neon and argon pellets at low temperatures because the material strength is too high. Pellet temperatures must be kept low (to well below the triple-point temperature of the material) to ensure minimal gas flow into the machine due to vapor pressure of the pellet. A gas-driven punch device has been designed and tested to dislodge pure neon or argon pellets. The breakaway strength of a pellet is proportional to the surface area of the pellet in contact with the inner diameter of the barrel. As pellets get larger in diameter, the amount of force needed to dislodge them increases. To better understand the mechanics behind how a punch dislodges a pellet, a solenoid-operated punch was designed so that kinetic energy of the punch, when striking a pellet, can be varied by changing input current to the solenoid. This solenoid punch will be used to determine kinetic energy versus pellet surface area threshold for breakaway. These data will be used to design mechanical punches for use in a high-field tokamak environment. This paper outlines the modeling, design, experimental testing, and results of the punch development activities.