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
Reactor Physics
The division's objectives are to promote the advancement of knowledge and understanding of the fundamental physical phenomena characterizing nuclear reactors and other nuclear systems. The division encourages research and disseminates information through meetings and publications. Areas of technical interest include nuclear data, particle interactions and transport, reactor and nuclear systems analysis, methods, design, validation and operating experience and standards. The Wigner Award heads the awards program.
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.”
Robert E. Einziger, Robert V. Strain
Nuclear Technology | Volume 75 | Number 1 | October 1986 | Pages 82-95
Technical Paper | Nuclear Fuel | doi.org/10.13182/NT86-A15979
Articles are hosted by Taylor and Francis Online.
Oxidation tests on spent-fuel fragments and rod segments were conducted between 250 and 360°C to relate temperature and defect size to fuel oxidation rate and time-to-cladding-splitting. Defect sizes from an equivalent circular diameter of 8 µm (the approximate size of a stress-corrosion-cracking-type breach) to 760 µm were used. Samples, held at temperature in a flowing air atmosphere, were frequently weighed and visually observed to determine the oxidation rate and effects of oxidation. Both the size and shape of the defect appear to influence the time-to-cladding-splitting. Above 283 °C, time-to-cladding-splitting was longer for the sharp small defect than for the large circular defect, an effect that diminished as the temperature decreased. By 250°C the sharp small defects split open before the large circular defects, indicating that, at lower temperatures, the defect’s shape and not its size may be more important when determining time-to-cladding-splitting. At both 283 and 295°C, the defects in fuel rod segments with lower burnups propagated sooner than those in rod segments with higher burnup from the same parent rod. The cumulative damage fraction approach, using a reasonable decreasing time/temperature profile, was applied to determine time-to-cladding-splitting for pressurized water reactor (PWR) fuel with a burnup >640 MWh/kg of uranium. Breached PWR fuel rods will not split open from fuel oxidation during 100 yr of storage if the rod is not exposed to air until the temperature drops below 230°C. Lower burnup fuel apparently requires lower temperature limits. The temperature limits appear to depend more on the time/temperature profile in the storage container than on oxidation rates.