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
Fusion Energy
This division promotes the development and timely introduction of fusion energy as a sustainable energy source with favorable economic, environmental, and safety attributes. The division cooperates with other organizations on common issues of multidisciplinary fusion science and technology, conducts professional meetings, and disseminates technical information in support of these goals. Members focus on the assessment and resolution of critical developmental issues for practical fusion energy applications.
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.
J. R. L. de Ladonchamps, L. M. Grossman
Nuclear Science and Engineering | Volume 12 | Number 2 | February 1962 | Pages 238-242
Technical Paper | doi.org/10.13182/NSE62-A26063
Articles are hosted by Taylor and Francis Online.
The space energy distribution of neutrons diffusing in a source-free, nonabsorbing medium possessing a temperature gradient is obtained by solving the appropriate Boltzmann equation to a second order approximation using the expansion technique of Chapman and Enskog. The medium is assumed to possess a locally Maxwellian energy distribution and the neutron scattering is taken to be isotropic in the laboratory system of coordinates. It is found that the neutron current is increased in the direction of a negative temperature gradient and the “thermal diffusion” transport coefficient is evaluated as a function of the mass of the moderator nuclei. For the case of infinite mass nuclei, the results correspond to the kinetic theory model of a Knudsen gas in a binary Lorentzian gas mixture. An analysis of the results is carried out in the framework of the thermodynamic theory of coupled irreversible processes.