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
Accelerator Applications
The division was organized to promote the advancement of knowledge of the use of particle accelerator technologies for nuclear and other applications. It focuses on production of neutrons and other particles, utilization of these particles for scientific or industrial purposes, such as the production or destruction of radionuclides significant to energy, medicine, defense or other endeavors, as well as imaging and diagnostics.
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
Norway’s Halden reactor takes first step toward decommissioning
The government of Norway has granted the transfer of the Halden research reactor from the Institute for Energy Technology (IFE) to the state agency Norwegian Nuclear Decommissioning (NND). The 25-MWt Halden boiling water reactor operated from 1958 to 2018 and was used in the research of nuclear fuel, reactor internals, plant procedures and monitoring, and human factors.
A. Rastas, J. Saastamoinen
Nuclear Science and Engineering | Volume 36 | Number 3 | June 1969 | Pages 351-360
Technical Paper | doi.org/10.13182/NSE69-A18733
Articles are hosted by Taylor and Francis Online.
Neutron rethermalization has been studied, experimentally and theoretically, in a system intended to reproduce the conditions of the Kottwitz problem. Terphenyl and light water were used as the moderators at the temperatures 223 and 11°C, respectively. The energy spectrum of the angle-dependent neutron flux perpendicular to the plane discontinuity was measured in terphenyl as a function of the distance from the discontinuity by means of an extraction channel and a choppertime-of-flight analyzer. The spatial behavior of the flux-weighted average energy was determined by fitting a Maxwellian to each measured spectrum using the method of the least squares. This spatial behavior could be satisfactorily described by a simple one-exponential function for distances exceeding 3 mm (measured from the discontinuity). The least-squares fit gave a value of 11.3 mm for the relaxation length. The theoretical calculations were performed by an approximate method using the “two overlapping-groups” approximation for the energy dependence. For the angular dependence of the flux, both the Pn(n =1,3)- and the DPn(n = 1)-approximation was used. Three different scattering models were used for each moderator. Rather good agreement with the theory and the experiment was achieved as to both the form of the spectrum and the spatial behavior of the average energy.