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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.
Robert W. Rice, John C. Walton
Nuclear Technology | Volume 163 | Number 1 | July 2008 | Pages 15-23
Technical Paper | High-Level Radioactive Waste Management | doi.org/10.13182/NT08-A3965
Articles are hosted by Taylor and Francis Online.
A numerical experiment was performed in order to examine the ability of multiple Monte Carlo realizations of a numerical model to reproduce the risk from a hypothetically known waste disposal situation. In the analysis, the risk was summarized by several risk metrics that could be chosen by a regulatory agency to set a risk standard. In the numerical experiment, the parameters in the numerical model are systematically varied to adjust bias (conservative or nonconservative) and to increase uncertainty relative to the hypothetically known future. The influence of parameter bias and uncertainty on the accuracy of each risk metric in predicting the nominal risk was evaluated and presented graphically. These analyses concluded that the peak-of-the-mean metric provides the least stable and least accurate risk predictions, whereas the cumulative release metric and mean of the peaks are more stable and accurate. The peak-of-the-mean and peak-of-the-median metrics exhibit risk dilution (i.e., a decrease in the predicted risk with increased uncertainty) and tend to underpredict risk. Additionally, these results illustrated how risk predictions that are made using what may be considered "conservative" assumptions can be moved in a direction that may or may not be expected or intended. Simulation relative to a hypothetical future (i.e., the nominal case) provides insight into the numerical behavior and potential accuracy of our risk assessment tools and potential issues with setting regulatory standards.