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Nuclear Criticality Safety
NCSD provides communication among nuclear criticality safety professionals through the development of standards, the evolution of training methods and materials, the presentation of technical data and procedures, and the creation of specialty publications. In these ways, the division furthers the exchange of technical information on nuclear criticality safety with the ultimate goal of promoting the safe handling of fissionable materials outside reactors.
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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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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.
Per Seltborg, Jan Wallenius, Kamil Tucek, Waclaw Gudowski
Nuclear Science and Engineering | Volume 145 | Number 3 | November 2003 | Pages 390-399
Technical Paper | doi.org/10.13182/NSE03-A2390
Articles are hosted by Taylor and Francis Online.
In order to study the beam power amplification of an accelerator-driven system (ADS), a new parameter, the proton source efficiency * is introduced. * represents the average importance of the external proton source, relative to the average importance of the eigenmode production, and is closely related to the neutron source efficiency [varphi]*, which is frequently used in the ADS field. [varphi]* is commonly used in the physics of subcritical systems driven by any external source (spallation source, (d,d), (d,t), 252Cf spontaneous fissions, etc.). On the contrary, * has been defined in this paper exclusively for ADS studies where the system is driven by a spallation source. The main advantage with using * instead of [varphi]* for ADS is that the way of defining the external source is unique and that it is proportional to the core power divided by the proton beam power, independent of the neutron source distribution.Numerical simulations have been performed with the Monte Carlo code MCNPX in order to study * as a function of different design parameters. It was found that, in order to maximize * and therefore minimize the proton current needs, a target radius as small as possible should be chosen. For target radii smaller than ~30 cm, lead-bismuth is a better choice of coolant material than sodium, regarding the proton source efficiency, while for larger target radii the two materials are equally good. The optimal axial proton beam impact was found to be located ~20 cm above the core center. Varying the proton energy, */Ep was found to have a maximum for proton energies between 1200 and 1400 MeV. Increasing the americium content in the fuel decreases * considerably, in particular when the target radius is large.
