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2025 ANS Winter Conference & Expo
November 9–12, 2025
Washington, DC|Washington Hilton
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The journey of the U.S. fuel cycle
Craig Piercycpiercy@ans.org
While most big journeys begin with a clear objective, they rarely start with an exact knowledge of the route. When commissioning the Lewis and Clark expedition in 1803, President Thomas Jefferson didn’t provide specific “turn right at the big mountain” directions to the Corps of Discovery. He gave goal-oriented instructions: explore the Missouri River, find its source, search for a transcontinental water route to the Pacific, and build scientific and cultural knowledge along the way.
Jefferson left it up to Lewis and Clark to turn his broad, geopolitically motivated guidance into gritty reality.
Similarly, U.S. nuclear policy has begun a journey toward closing the U.S. nuclear fuel cycle. There is a clear signal of support for recycling from the Trump administration, along with growing bipartisan excitement in Congress. Yet the precise path remains unclear.
J. T. Birkholzer, N. Halecky, S. W. Webb, P. F. Peterson, G. S. Bodvarsson
Nuclear Technology | Volume 163 | Number 1 | July 2008 | Pages 147-164
Technical Paper | High-Level Radioactive Waste Management | doi.org/10.13182/NT08-A3978
Articles are hosted by Taylor and Francis Online.
In heated drifts such as those designated for emplacement of radioactive waste at the proposed geologic repository at Yucca Mountain, temperature gradients cause natural-convection processes that may significantly influence the moisture conditions in the drifts and in the surrounding fractured rock. Large-scale convection cells in the heated drifts would provide an effective mechanism for turbulent mixing and axial transport of vapor generated from evaporation of pore water in the nearby formation. As a result, vapor would be transported from the elevated-temperature sections of the drifts into cool end sections (where no waste is emplaced), would condense there, and subsequently would drain into underlying rock units. To study these processes, we have developed a new simulation method that couples existing tools for simulating thermal-hydrological conditions in the fractured formation with a module that approximates turbulent natural convection in heated emplacement drifts. The new method simultaneously handles (a) the flow and energy transport processes in the fractured rock, (b) the flow and energy transport processes in the cavity, and (c) the heat and mass exchange at the rock-cavity interface. An application is presented studying the future thermal-hydrological conditions within and near a representative waste emplacement drift at Yucca Mountain. Particular focus is on the potential for condensation along the emplacement section, a possible result of heat output differences between individual waste packages.