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Isotopes & Radiation
Members are devoted to applying nuclear science and engineering technologies involving isotopes, radiation applications, and associated equipment in scientific research, development, and industrial processes. Their interests lie primarily in education, industrial uses, biology, medicine, and health physics. Division committees include Analytical Applications of Isotopes and Radiation, Biology and Medicine, Radiation Applications, Radiation Sources and Detection, and Thermal Power Sources.
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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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The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
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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.
M. Segev
Nuclear Science and Engineering | Volume 67 | Number 2 | August 1978 | Pages 221-234
Technical Paper | doi.org/10.13182/NSE78-A15437
Articles are hosted by Taylor and Francis Online.
The Adler-Adler cross-section formalism with energy-dependent parameters is a practical approximation to the R-Matrix formalism, based on the smallness of the s-wave neutron width in fissile elements. Attempts have been made to represent experimental cross sections by the Adler-Adler formulas through an initial representation by the Reich-Moore approximation of R-Matrix and a subsequent conversion of the Reich-Moore formulas to the Adler-Adler formulas. Adler and Adler had foreseen difficulties in associating their formulas with approximate R-Matrix theories such as those of Reich-Moore. Indeed, it is shown that due to the nonunitarity of the Adler-Adler formalism on the one hand and the unitarity, by definition, of the Reich-Moore formalism on the other hand, the conversion from the latter to the former is ambiguous. Examples are shown to demonstrate that this ambiguity results in numerical inaccuracies, sometimes very large ones, for neutron widths that are not extremely small. Improved Adler-Adler-type formulas have been derived from the R-Matrix formalism. In these formulas, the multipliers of the Breit-Wigner resonance lines exhibit more explicit energy dependence than their original counterparts, mainly in the form of additional terms in the formula for the total cross section. The conversion from Reich-Moore cross sections to the improved resonance formulas is shown to be much less ambiguous and to produce very accurate cross sections. In particular, the inaccuracies encountered with the Reich-Moore-Adler-Adler conversion are eliminated. A computer code, PEDRA, was written to perform the conversion from a given set of Reich-Moore parameters to the parameters required in the improved formulas. The numerical algorithm of this code is based on an adaptation with modifications of the numerical approach of de Saussure-Perez in the POLLA code, which converts Reich-Moore parameters to Adler-Adler parameters.