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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
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.
Phiphat Phruksarojanakun, Paul P. H. Wilson
Nuclear Science and Engineering | Volume 156 | Number 2 | June 2007 | Pages 164-179
Technical Paper | doi.org/10.13182/NSE07-A2694
Articles are hosted by Taylor and Francis Online.
Three variance reduction techniques for the ongoing development of Monte Carlo isotopic inventory analysis are implemented as alternatives to improve the precision of Monte Carlo simulations. The Forced Reaction technique is designed to force an atom to undergo a predefined number of reactions in a given control volume. Biased Reaction Branching is primarily focused on improving statistical results of the isotopes that are produced from rare reaction pathways. Biased Source Sampling is aimed at increasing frequencies of sampling rare initial isotopes as the starting Monte Carlo particles. A variety of test problems is uniquely designed to demonstrate the validity and the improvement, relative to the analog problem, of each technique. The increases in precision due to the variance reduction techniques usually come at the expense of longer computing times per history.A figure of merit (FOM) is developed as a tool to monitor the efficiency of Monte Carlo simulations with variance reduction schemes. A number of statistical characteristics of Monte Carlo isotopic inventory calculations are used to construct a variety of FOM formulations. Two of them offer robust FOMs: one based on the relative error of a known target isotope (1/R2T) and one based on the overall detection limit corrected by the relative error (1/DkR2T).Figures of merit are later used to quantitatively assess the efficiencies of Monte Carlo simulations under different scopes of interest. Given a defined set of variance reduction parameters to produce desired effects, the efficiency measurements from an FOM agree with the expected performance.
