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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.
Aldo Dall'Osso
Nuclear Science and Engineering | Volume 162 | Number 1 | May 2009 | Pages 109-116
Technical Paper | doi.org/10.13182/NSE162-109
Articles are hosted by Taylor and Francis Online.
Perturbation theory has been conceived to determine the effect of an external perturbation on the reactivity or, in its general formulation, on any other observable quantity, if it can be expressed as a ratio of linear functionals of the flux. Ronen (in 1979) introduced the inverse perturbation approach to extend some measurement results from a reactor system to another one. In constrained calculations, where the value of an external parameter is searched, with the constraint to reach a target value of an observable quantity, the use of the inverse approach rises quite naturally. A common example of this kind of problem is the search of the axial position of a control bank (the constrained parameter) leading the axial offset of the power distribution (the observable) to a target value. We present here an inverse general perturbation method, which has the advantage with respect to classical procedures used to solve this kind of problem, based on the iterative Newton-Raphson method, to reduce the computation time in situations where changes on the control parameter make a high distortion on the flux distribution, as it is the case of the control banks. Some numerical examples illustrate the performances and the gain in stability of this method in the case of control of the axial offset of the power distribution. Other examples show the application of the method to the determination of the number density of several isotopes constrained to several observables in a transport code. A simple algorithm to compute the generalized importance is proposed.