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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
ANS Student Conference 2025
April 3–5, 2025
Albuquerque, NM|The University of New Mexico
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
First astatine-labeled compound shipped in the U.S.
The Department of Energy’s National Isotope Development Center (NIDC) on March 31 announced the successful long-distance shipment in the United States of a biologically active compound labeled with the medical radioisotope astatine-211 (At-211). Because previous shipments have included only the “bare” isotope, the NIDC has described the development as “unleashing medical innovation.”
Scott D. Ramsey, Gregory J. Hutchens
Nuclear Science and Engineering | Volume 173 | Number 2 | February 2013 | Pages 197-205
Technical Note | doi.org/10.13182/NSE11-34
Articles are hosted by Taylor and Francis Online.
A quantity that is frequently of interest in stochastic neutronics calculations is the probability of extinction (POE), or its complement, the survival probability. Even within the simplest stochastic point kinetics formulations, the POE is typically extracted from numerical calculations or approximated. An example of the latter strategy involves the truncation of the fission multiplicity distribution at two, resulting in the “quadratic approximation.” While this methodology yields closed-form results for the POE, it is valid only for supercritical multiplication near unity. In this technical note, we attempt to obviate fission multiplicity truncation in the construction of transient and infinite time limit closed-form POE solutions. In the infinite time limit, we arrive at the necessity of solving a quintic algebraic equation; we provide a brief discussion of the mature formalism available for solving quintic equations and generate a variety of simple representations using hypergeometric series. We evaluate and discuss both the new and existing approximations in the context of an example 235U system and compare their validity over a range of supercritical multiplication factors.