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
Materials Science & Technology
The objectives of MSTD are: promote the advancement of materials science in Nuclear Science Technology; support the multidisciplines which constitute it; encourage research by providing a forum for the presentation, exchange, and documentation of relevant information; promote the interaction and communication among its members; and recognize and reward its members for significant contributions to the field of materials science in nuclear technology.
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.”
A. Ziya Akcasu, Louis M. Shotkin
Nuclear Science and Engineering | Volume 28 | Number 1 | April 1967 | Pages 72-81
Technical Paper | doi.org/10.13182/NSE67-A18669
Articles are hosted by Taylor and Francis Online.
The bounded periodic behavior of the reactor power is studied for those instances when the equilibrium power is greater than the critical power level. Simple formulas are derived, for reactors with arbitrary linear feedback and no delayed neutrons, for the amplitude and frequency of the limit cycles. These quantities are shown to be related to the ratio of the equilibrium-to-critical power level and to the Laplace transform of the feedback kernel. Since the techniques used apply for arbitrary values of the fundamental component of the power oscillation, they are used to derive a describing function which is valid for large amplitude disturbances. Conditions for the existence of critical power levels and, hence, limit cycles are discussed. Formulae for investigating the stability of these limit cycles are also derived. Applications are made to the circulating fuel reactor and to the two-temperature reactor. It is also suggested that the results can be used in two practical situations: 1) When the oscillation amplitude is indistinguishable from the reactor noise, the power level can exceed critical; and 2) When the oscillation amplitude is large, the reactor can be used as a self-sustained pulse-modulated neutron source.