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Conference Spotlight
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.
Yong Jin Cho, Gyoo Dong Jeun
Nuclear Technology | Volume 158 | Number 3 | June 2007 | Pages 366-377
Technical Paper | Thermal Hydraulics | doi.org/10.13182/NT07-A3848
Articles are hosted by Taylor and Francis Online.
The header of a Canada deuterium uranium reactor (CANDU) is an important component in simulating the fuel channel behavior because the header's hydraulic behavior controls the feeder void fraction, which affects the fuel bundle coolability. In CANDU accident analyses, the liquid entrainment and vapor pull-through (off-take) phenomena should be considered when horizontal stratification is achieved inside the header. The current RELAP5 off-take model can treat only three directions: vertical upward, vertical downward, and side oriented junctions. In this study, the RELAP5 off-take model was modified and generalized by considering the geometric effect of branch angles. Based on Craya's approach, the critical height correlation was reconstructed by use of the branch line connection angle. The new model in RELAP5/CANDU could be applied to vertical upward, vertical downward, and angled branch. The verification and validation analyses for this new model were performed using separate effect test and integral effect test results. The verification and validation analyses show improved accuracy with the new model.