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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
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.
Chunyan Li, Junli Li, Jianping Cheng, Zhen Wu, Lucheng Pei, Jiajin Fan
Nuclear Science and Engineering | Volume 159 | Number 3 | July 2008 | Pages 284-295
Technical Paper | doi.org/10.13182/NSE159-284
Articles are hosted by Taylor and Francis Online.
In the calculation of point flux by Monte Carlo simulation, there is a special disadvantage in the mostly used method of next event estimation (NEE) for which theoretical variance is infinite. And, this problem has not yet been solved satisfactorily. The purpose of this paper is to provide some new ideas to solve the problem of infinite variance without introducing any bias for the mean. To eliminate the unbounded factors, the relations among the different state variables for two neighboring collisions are analyzed; then, on the basis of the integral expression of the once-more scattered flux contribution to the point detector, by changing the state variables to be sampled, six basic methods are derived - two of them are NEE and collision probability estimation, and four are new methods. Furthermore, based on one of the new methods, by variable substitution, a new method called exponent biased sample estimation (EBS) is obtained that can eliminate the [arrow over]rd - [arrow over]rm-2 singularity factor and has no exponent factor, which exists in other methods. The benchmark results show that EBS is much better than NEE with the variance of one order of magnitude smaller and a figure-of-merit factor of several hundreds higher sometimes, and its calculation efficiency is higher than that of the once more collision flux estimation method. Compared with the direction biased sample estimation method, EBS has no advantage in variance, but the sample procedures are much simpler and use less CPU time.