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
Operations & Power
Members focus on the dissemination of knowledge and information in the area of power reactors with particular application to the production of electric power and process heat. The division sponsors meetings on the coverage of applied nuclear science and engineering as related to power plants, non-power reactors, and other nuclear facilities. It encourages and assists with the dissemination of knowledge pertinent to the safe and efficient operation of nuclear facilities through professional staff development, information exchange, and supporting the generation of viable solutions to current issues.
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.”
Christopher S. Handwerk, Michael J. Driscoll, Pavel Hejzlar
Nuclear Technology | Volume 164 | Number 3 | December 2008 | Pages 320-336
Technical Paper | Fission Reactors | doi.org/10.13182/NT08-A4030
Articles are hosted by Taylor and Francis Online.
The gas-cooled fast reactor (GFR) has received increased attention in the past decade under the impetus provided by the Generation-IV International Forum. The GFR given principal attention is a version using helium as a coolant. However, the work presented here is for a core using supercritical carbon dioxide (S-CO2) as a coolant, in a direct Brayton cycle, which has comparable cycle efficiency (~45%) at much lower temperatures (e.g., 650°C versus 850°C) than helium-based cycles.A reactor core for use in this direct cycle S-CO2 GFR has been designed that satisfies established neutronic and thermal-hydraulic steady-state design criteria, while concurrently supporting the Gen-IV criteria of sustainability, safety, proliferation, and economics. Use of innovative tube-in-duct fuel has been central to accomplishing this objective, as it provides a higher fuel volume fraction and lower fuel temperatures and pressure drop when compared to traditional pin-type fuel. Further, this large fuel volume fraction allows for a large enough heavy metal loading for a sustainable core lifetime without the need for external blankets, enhancing the proliferation resistance of such an approach. It was not possible to achieve a sustainable core (i.e., conversion ratio = 1.0) using conventional pin-type oxide fuel.Use of beryllium oxide (BeO) as a diluent is explored as a means for both power shaping and coolant void reactivity (CVR) reduction, similar to the studies carried out earlier for the sodium-cooled European Fast Reactor. Results show that relatively flat power profiles can be maintained throughout a batch-loaded "battery" core life of more than 15 yr using a combination of fissile concentration and diluent zoning, due to the moderating effect of the BeO. Combining BeO diluent with the innovative strategy of using a thick volume of S-CO2 coolant in the radial reflector yields negative CVR values throughout core life, a rare, if not unique accomplishment for fast reactors. The ability to maintain negative CVR comes from a combination of the effects of spectral softening due to the BeO diluent and the enhanced leakage upon voiding of the S-CO2 radial reflector.
