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Division Spotlight
Thermal Hydraulics
The division provides a forum for focused technical dialogue on thermal hydraulic technology in the nuclear industry. Specifically, this will include heat transfer and fluid mechanics involved in the utilization of nuclear energy. It is intended to attract the highest quality of theoretical and experimental work to ANS, including research on basic phenomena and application to nuclear system design.
Meeting Spotlight
ANS Student Conference 2025
April 3–5, 2025
Albuquerque, NM|The University of New Mexico
Standards Program
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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Latest News
First astatine-labeled compound shipped in the U.S.
The Department of Energy’s National Isotope Development Center (NIDC) on March 31 announced the successful long-distance shipment in the United States of a biologically active compound labeled with the medical radioisotope astatine-211 (At-211). Because previous shipments have included only the “bare” isotope, the NIDC has described the development as “unleashing medical innovation.”
E. E. Lewis, F. T. Adler
Nuclear Science and Engineering | Volume 31 | Number 1 | January 1968 | Pages 117-126
Technical Paper | doi.org/10.13182/NSE68-A18014
Articles are hosted by Taylor and Francis Online.
A method has been developed for calculating resonance effects in nuclear reactor lattices without the two widely used assumptions: 1) that the neutron flux is spatially independent within each region of the lattice cell; 2) that the flux recovers an asymptotic l/E form between resonances. The neutron slowing down problem is formulated in terms of a Boltzmann integral equation, and the correct transport kernel is derived for a Wigner-Seitz equivalent cell with isotropic scattering in the laboratory system. A new method of polynomial approximations is then used to reduce the transport problem to matrix form. The result is a set of integral equations in lethargy for the neutron flux at a number of discrete ordinates. These equations are numerically integrated to obtain the neutron flux as a function of position and energy. Resolved resonance integrals are calculated for a number of 238U-graphite lattices with both metal and oxide rods. Where comparisons are made, the results are in excellent agreement with accurate Monte Carlo calculations. Both the flat flux and flux recovery assumptions are found to cause significant overestimates of the resonance integrals, the errors increasing with the rod radii. The temperature coefficients, however, are less sensitive to these assumptions.