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Division Spotlight
Mathematics & Computation
Division members promote the advancement of mathematical and computational methods for solving problems arising in all disciplines encompassed by the Society. They place particular emphasis on numerical techniques for efficient computer applications to aid in the dissemination, integration, and proper use of computer codes, including preparation of computational benchmark and development of standards for computing practices, and to encourage the development on new computer codes and broaden their use.
Meeting Spotlight
Utility Working Conference and Vendor Technology Expo (UWC 2024)
August 4–7, 2024
Marco Island, FL|JW Marriott Marco Island
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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“You’ve got this; we’ve got this”
Lisa Marshallpresident@ans.org
Thank you for the opportunity to serve as your American Nuclear Society president. The support from within the Society, academia, professional organizations, and international partners has been heartwarming. Students have expressed joy about what the future holds, and they are ready, as am I, to be part of keeping the industry moving forward.
The year 2001 was pivotal for me; it represented my start in nuclear engineering. My career has centered around precollege and university students. To be cliché, they are our future, and we must continue to support their maturation in the field and in ANS. My cup is full when students thrive, and the Society has made many gains in this arena. We have a robust K-12 STEM program that continues to be refined, and partners among educators and organizations that strengthen the routes into the discipline.
Rene Sanchez, David Loaiza, Robert Kimpland, David Hayes, Charlene Cappiello, Mark Chadwick
Nuclear Science and Engineering | Volume 158 | Number 1 | January 2008 | Pages 1-14
Technical Paper | doi.org/10.13182/NSE08-A2734
Articles are hosted by Taylor and Francis Online.
A series of critical-mass experiments using a 6-kg neptunium sphere was performed on the Planet vertical-assembly machine at Los Alamos National Laboratory (LANL). The purpose of the experiments was to obtain a better estimate of the critical mass of 237Np. The configurations that were studied included surrounding the neptunium sphere with highly enriched uranium (HEU) shells as well as reflecting it with iron and polyethylene. An additional experiment using a 4.5-kg -phase plutonium sphere surrounded with HEU was performed to demonstrate how well the computer transport code and the existing cross-section data for uranium and plutonium could reproduce the experiment. For some of the configurations, the prompt-neutron decay constants at delayed critical were measured. These experiments provided an integral measurement of the cross sections for 237Np in the fast-energy and possibly in the intermediate-energy regions. The measured keff from these experiments was compared with the calculated keff from the Monte Carlo N-Particle (MCNP) transport code using ENDF/B-V and ENDF/B-VI and cross-section data evaluated by the Nuclear Theory and Applications group (T-16) at LANL. In all the neptunium experiments, the calculated keff values based on ENDF/B-VI data were ~1% lower than the experimental keff. After adjusting the cross sections for neptunium and 235U to match the bare neptunium/HEU experiment as well as Godiva keff criticality and spectra indexes, the MCNP code yielded a value of 57 ± 4 kg for the bare critical mass of 237Np.