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International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2025)
April 27–30, 2025
Denver, CO|The Westin Denver Downtown
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Argonne’s METL gears up to test more sodium fast reactor components
Argonne National Laboratory has successfully swapped out an aging cold trap in the sodium test loop called METL (Mechanisms Engineering Test Loop), the Department of Energy announced April 23. The upgrade is the first of its kind in the United States in more than 30 years, according to the DOE, and will help test components and operations for the sodium-cooled fast reactors being developed now.
Harvey J. Amster, K. Cheuk Chan
Nuclear Science and Engineering | Volume 61 | Number 3 | November 1976 | Pages 388-398
Technical Paper | doi.org/10.13182/NSE76-A26925
Articles are hosted by Taylor and Francis Online.
An elementary function for the collision density of neutrons slowing down from a plane source in hydrogen is synthesized through a set of schemes incorporating several known explicit features of the exact solution. First, the Marshak distribution is assigned a distorted lethargy variable that makes its zeroth and second spatial moments exact at all lethargies while automatically preserving its detailed accuracy at large lethargies. The same exact moments are also required of a specific functional form able to assume the correct spatial dependence at small lethargies. Then, a linear combination of these functions is constructed with coefficients making the two moments and the first spatial derivative at the source plane exact at all lethargies. The resulting distribution automatically becomes correct at both lethargy extremes. In addition, a remaining lethargy-dependent parameter makes the fourth spatial moment exact at all lethargies except within a finite interval of intermediate values, where its error must reach a maximum of 2.7%. Extraneous roots from multiple bifurcations of the parameter are identified by their unphysical implications. For computational simplicity, both this parameter and the incorporated function for the exact spatial derivative at the source plane are replaced by fitted elementary functions. The resulting expression for the collision density agrees very closely with McInerney's Monte Carlo calculations. Some extensions are described in a separate Note.