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Division Spotlight
Nuclear Installations Safety
Devoted specifically to the safety of nuclear installations and the health and safety of the public, this division seeks a better understanding of the role of safety in the design, construction and operation of nuclear installation facilities. The division also promotes engineering and scientific technology advancement associated with the safety of such facilities.
Meeting Spotlight
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
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
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.
Ayman I. Hawari, Iyad I. Al-Qasir, Abderrafi M. Ougouag
Nuclear Science and Engineering | Volume 155 | Number 3 | March 2007 | Pages 449-462
Technical Paper | Mathematics and Computation, Supercomputing, Reactor Physics and Nuclear and Biological Applications | doi.org/10.13182/NSE07-A2676
Articles are hosted by Taylor and Francis Online.
In both the prismatic and pebble bed designs of very high temperature reactors, the graphite moderator is expected to reach exposure levels of 1021 to 1022 n/cm2 over the lifetime of the reactor. This exposure results in damage to the graphite structure. Studies of the thermal properties of irradiated graphite show changes in the thermal conductivity and (to a lesser extent) the heat capacity at fluences <1021 n/cm2. In graphite, these properties depend on the behavior of atomic vibrations (phonons) in the solid. Therefore, it can be expected that alterations in the phonon behavior that would produce changes in these properties would have an impact on the thermal neutron scattering behavior of that material. In this work, an atomistic ab initio investigation is performed to explore the potential impact of simple carbon interstitial formations on the inelastic thermal neutron scattering behavior of graphite. Using the VASP/PHONON code system, graphite supercells were modeled with and without either a single carbon interstitial or a di-interstitial (C2) molecule between the graphite planes. This resulted in the production of the phonon frequency spectra for these structures. From the phonon data, the inelastic thermal neutron scattering cross sections were generated, using the NJOY code system, at temperatures of 300 and 1200 K. A comparison of the generated cross sections shows that accounting for the interstitials in the calculations affects the cross sections mainly in the energy range from 0.01 to 0.1 eV.