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
Fuel Cycle & Waste Management
Devoted to all aspects of the nuclear fuel cycle including waste management, worldwide. Division specific areas of interest and involvement include uranium conversion and enrichment; fuel fabrication, management (in-core and ex-core) and recycle; transportation; safeguards; high-level, low-level and mixed waste management and disposal; public policy and program management; decontamination and decommissioning environmental restoration; and excess weapons materials disposition.
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.”
T. H. Newton, Jr., M. S. Kazimi, E. E. Pilat
Nuclear Science and Engineering | Volume 157 | Number 3 | November 2007 | Pages 264-279
Technical Paper | doi.org/10.13182/NSE07-A2727
Articles are hosted by Taylor and Francis Online.
The Massachusetts Institute of Technology (MIT) Reactor II (MITR-II) is a 5-MW research reactor presently fueled with highly enriched uranium (HEU) in uranium-aluminum plate-type elements. A low-enriched uranium (LEU)-fueled core has been designed using 20% enriched monolithic uranium-molybdenum fuel that maintains high experimental neutron flux and increases flexibility in meeting the needs of experiments. The configuration of the new plate fuel elements was selected using a full-core MCNP model, with which different in-core materials were evaluated to optimize the neutron fluxes, reactivity, and experimental neutron spectrum. In-core materials were chosen to meet experimental flux level and spectrum needs. Of the designs evaluated, the most promising consisted of half-width fuel elements with nine U-7Mo LEU fuel plates.Results from the MCNP/ORIGEN linkage code MCODE depletion calculations showed that the refueling interval of the chosen LEU core would be twice as long as the HEU core at the same power level. Thermal-hydraulic analysis using the MULtiCHannel analysis code II (MULCH-II) indicated that the peak channel will remain below the onset of nucleate boiling under normal and loss-of-flow conditions. A thermal-hydraulic evaluation of the limiting channel using point kinetics showed that the LEU core could withstand a step reactivity insertion of 3.92 $, increasing by 60% the allowable reactivity for an in-core experiment. Finally, preliminary analyses show that it may be feasible to use the proposed design to double the core power, if the fuel cycle length is to be kept at its present length.