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.
Alan H. Wells, Albert J. Machiels
Nuclear Technology | Volume 176 | Number 3 | December 2011 | Pages 387-394
Technical Paper | Radiation Transport and Protection | doi.org/10.13182/NT11-A13315
Articles are hosted by Taylor and Francis Online.
According to the U.S. Nuclear Regulatory Commission's guidance based on concerns for potential channeling of neutrons between absorber particles, the criticality safety of transportation systems should not rely on credit for >75% of the boron in fixed neutron absorbers. The 75% efficiency (or effectiveness) factor was first formulated in 1987 for a cask to transport spent fuel from the Fermi Unit 1 (Fermi-1) fast breeder reactor. Fermi-1 fuel was highly enriched (25.6 wt%), and a critical condition could possibly be achieved in a dry environment. The 75% factor was later expanded to include low-enriched light water reactor (LWR) spent fuel, although the latter cannot achieve a critical state without the presence of a moderator. Under flooded conditions, the net effect of channeling is significantly reduced because the neutrons are nearly isotropically scattered by the moderator and impact the neutron absorber from all possible directions. Under dry conditions or under conditions representative in neutron attenuation measurements for absorber qualification, the neutrons impact the absorber mostly perpendicularly, and neutron channeling is maximized. The effect of neutron channeling for the Fermi-1 fuel and for a typical LWR fuel shipment was quantified using a methodology developed to apply experimental transmission data to calculations of the neutron angular distribution at the neutron absorber sheet, yielding the strength of the neutron channeling effect for a particular fuel type and cask basket geometry. These analyses show that neutron absorber qualification via a collimated neutron transmission measurement conservatively bounds the neutron channeling effect. Further imposition of a 75%-only credit leads to an overly conservative amount in neutron absorbers. For transport applications of LWR spent fuel, this results in increased costs with no measurable benefits to criticality safety.