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Division Spotlight
Radiation Protection & Shielding
The Radiation Protection and Shielding Division is developing and promoting radiation protection and shielding aspects of nuclear science and technology — including interaction of nuclear radiation with materials and biological systems, instruments and techniques for the measurement of nuclear radiation fields, and radiation shield design and evaluation.
Meeting Spotlight
2024 ANS Annual Conference
June 16–19, 2024
Las Vegas, NV|Mandalay Bay Resort and Casino
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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Nuclear Science and Engineering
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Fusion Science and Technology
Latest News
Fusion Energy Week begins today
Fusion is riding a surge of attention that began in December 2022 when researchers at Lawrence Livermore National Laboratory’s National Ignition Facility achieved fusion ignition. The organizers of Fusion Energy Week—a group called the U.S. Fusion Outreach Team—on the other hand, trace fusion development back 100 years to the doctoral research of Cecilia Payne-Gaposchkin, who discovered that stars, including our Sun, are mostly made of hydrogen and helium, which in turn led to the understanding that those elements are the “fuel” of potential fusion energy systems on Earth. In recognition of Payne-Gaposchkin’s birthday—May 10—the U.S. Fusion Outreach Team plans to hold a “grassroots celebration of fusion energy” May 6–10, 2024, and annually during the second week of May.
Taro Ueki, Edward W. Larsen
Nuclear Science and Engineering | Volume 130 | Number 3 | November 1998 | Pages 269-291
Technical Paper | doi.org/10.13182/NSE98-A2006
Articles are hosted by Taylor and Francis Online.
A new Boltzmann Monte Carlo (BMC) equation is proposed to describe the transport of Monte Carlo particles governed by a set of nonanalog rules for the transition of space, velocity, and weight. The BMC equation is a kinetic equation that includes weight as an extra independent variable. The solution of the BMC equation is the pointwise distribution of velocity and weight throughout the physical system. The BMC equation is derived for the simulation of a transmitted current, utilizing the exponential transform with angular biasing. The weight moments of the solution of the BMC equation are used to predict the score moments of the transmission current. (Also, it is shown that an adjoint BMC equation can be used for this purpose.) Integrating the solution of the forward BMC equation over space, velocity, and weight, the mean number of flights per history is obtained. This is used to determine theoretically the figure of merit for any choice of biasing parameters. Also, a maximum safe value of the exponential transform parameter is proposed, which ensures the finite variance of variance estimate (sample variance) for any penetration distance. Finally, numerical results that validate the new theory are provided.