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
Isotopes & Radiation
Members are devoted to applying nuclear science and engineering technologies involving isotopes, radiation applications, and associated equipment in scientific research, development, and industrial processes. Their interests lie primarily in education, industrial uses, biology, medicine, and health physics. Division committees include Analytical Applications of Isotopes and Radiation, Biology and Medicine, Radiation Applications, Radiation Sources and Detection, and Thermal Power Sources.
Meeting Spotlight
International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2025)
April 27–30, 2025
Denver, CO|The Westin Denver Downtown
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
June 2025
Nuclear Technology
Fusion Science and Technology
May 2025
Latest News
Argonne’s METL gears up to test more sodium fast reactor components
Argonne National Laboratory has successfully swapped out an aging cold trap in the sodium test loop called METL (Mechanisms Engineering Test Loop), the Department of Energy announced April 23. The upgrade is the first of its kind in the United States in more than 30 years, according to the DOE, and will help test components and operations for the sodium-cooled fast reactors being developed now.
V. K. Paré, J. T. Mihalczo
Nuclear Science and Engineering | Volume 56 | Number 2 | February 1975 | Pages 213-218
Technical Note | doi.org/10.13182/NSE75-A26662
Articles are hosted by Taylor and Francis Online.
A theory is developed for the cross-power spectral densities between the signal from an ionization chamber containing a 252Cf neutron source, which provides the initiation of fission chains in a reactor or neutron multiplying assembly, and the signals from detectors of particles from fission chains in the reactor. Previously derived spectral densities between two detectors are modified to include the effects of the inherent and 252Cf source in the reactor. Calculations of the amplitude of the coherence function for noise measurements, both conventional and 252Cf, for the reactor at the Fast Flux Test Facility are presented and can be used to estimate the time required for a measurement with a given precision. The equivalence between the expressions developed here and those previously developed for time-domain measurements of this type is also shown. Use of a 252Cf chamber makes possible a new method of determination of the reactivity which is independent of the inherent source strength and detection efficiency. This method does not require a calibration near delayed criticality as do the previously used methods such as break frequency or coherence amplitude noise analysis and modified source multiplication measurements. It requires the knowledge of some properties of the ionization chamber containing 252Cf which can be determined outside the reactor. Since this method does not require a calibration near delayed criticality, it may be used in the initial loading of a reactor to determine the reactivity before criticality is achieved. The independence of detection efficiency also makes it useful during initial loading, since large changes in detection efficiency can occur with loading. The independence of the method on the inherent source would be advantageous during refueling of a reactor when the inherent source in the fresh fuel inserted may be much less than that of the burnt-up fuel removed. The method may also be useful in determining the reactivity of assemblies where sufficient fuel to achieve criticality is not available.
