ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
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
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!
Latest Magazine Issues
Apr 2025
Jan 2025
Latest Journal Issues
Nuclear Science and Engineering
May 2025
Nuclear Technology
April 2025
Fusion Science and Technology
Latest News
General Kenneth Nichols and the Manhattan Project
Nichols
The Oak Ridger has published the latest in a series of articles about General Kenneth D. Nichols, the Manhattan Project, and the 1954 Atomic Energy Act. The series has been produced by Nichols’ grandniece Barbara Rogers Scollin and Oak Ridge (Tenn.) city historian David Ray Smith. Gen. Nichols (1907–2000) was the district engineer for the Manhattan Engineer District during the Manhattan Project.
As Smith and Scollin explain, Nichols “had supervision of the research and development connected with, and the design, construction, and operation of, all plants required to produce plutonium-239 and uranium-235, including the construction of the towns of Oak Ridge, Tennessee, and Richland, Washington. The responsibility of his position was massive as he oversaw a workforce of both military and civilian personnel of approximately 125,000; his Oak Ridge office became the center of the wartime atomic energy’s activities.”
Stefano Terlizzi, Dan Kotlyar
Nuclear Science and Engineering | Volume 193 | Number 9 | September 2019 | Pages 948-965
Technical Paper | doi.org/10.1080/00295639.2019.1583948
Articles are hosted by Taylor and Francis Online.
This paper presents the theoretical foundations and the practical implementation of the Fission Matrix Decomposition (FMD) method. The FMD method is a hybrid technique for the rapid and accurate solution of the criticality transport problem in highly heterogeneous media. The method relies on a two-stage sequence, conceptually similar to the approach adopted by production codes, such as CASMO/SIMULATE. First, a database of local fission matrices and coupling coefficients is generated through Monte Carlo calculations. The database is then used to reconstruct the full fission matrix, from which multiplication factor and fission source distribution are computed with a deterministic eigensolver. The FMD method is here tested against two stylized problems: (1) the pressurized water reactor unit-cell problem and (2) the resource-renewable boiling water assembly problem. The accuracy and computational efficiency of the FMD method are compared against the continuous-energy Monte Carlo Fission Source Iteration method, the Fission Matrix-Based Monte Carlo approach, and the lattice-diffusion approximation. For the analyzed cases, the FMD was 100 times faster than diffusion, while maintaining transport accuracy with a mean absolute percent error lower than 1% on the fission source distribution and difference in multiplication factor below 7 pcm.
