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Division Spotlight
Nuclear Nonproliferation Policy
The mission of the Nuclear Nonproliferation Policy Division (NNPD) is to promote the peaceful use of nuclear technology while simultaneously preventing the diversion and misuse of nuclear material and technology through appropriate safeguards and security, and promotion of nuclear nonproliferation policies. To achieve this mission, the objectives of the NNPD are to: Promote policy that discourages the proliferation of nuclear technology and material to inappropriate entities. Provide information to ANS members, the technical community at large, opinion leaders, and decision makers to improve their understanding of nuclear nonproliferation issues. Become a recognized technical resource on nuclear nonproliferation, safeguards, and security issues. Serve as the integration and coordination body for nuclear nonproliferation activities for the ANS. Work cooperatively with other ANS divisions to achieve these objective nonproliferation policies.
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!
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Industry Update—May 2025
Here is a recap of industry happenings from the recent past:
TerraPower’s Natrium reactor advances on several fronts
TerraPower has continued making aggressive progress in several areas for its under-construction Natrium Reactor Demonstration Project since the beginning of the year. Natrium is an advanced 345-MWe reactor that has liquid sodium as a coolant, improved fuel utilization, enhanced safety features, and an integrated energy storage system, allowing for a brief power output boost to 500-MWe if needed for grid resiliency. The company broke ground for its first Natrium plant in 2024 near a retiring coal plant in Kemmerer, Wyo.
C.-K. Chris Wang, Thomas E. Blue, Reinhard Gahbauer
Nuclear Technology | Volume 84 | Number 1 | January 1989 | Pages 93-107
Technical Paper | Radioisotopes and Isotope Separation | doi.org/10.13182/NT89-A34199
Articles are hosted by Taylor and Francis Online.
A neutronic study of an accelerator-based neutron irradiation facility (ANIF) for boron neutron capture therapy (BNCT) was performed using three-dimensional Monte Carlo transport calculations. The major components of the ANIF are a radio-frequency quad-rupole proton accelerator, a 7Li target, and a moderator assembly. Neutrons are generated by bombarding the 7Li target with 2.5-MeV protons. The neutrons emerging from the 7Li target are too energetic to be used for BNCT and must therefore be moderated. Calculations show that, among all materials for the ANIF, beryllia (BeO) and heavy water (D2O) are the best moderators. Between them, beryllia provides better neutron spectra, but D2O gives higher neutron intensities. Adding alumina (Al2O3) to D2O improves the neutron spectra, but it also increases gamma-ray contamination. The overall performance of an ANIF was evaluated for a moderator assembly composed of a 20.0-cm-high x 12.5-cm-radius beryllia cylinder reflected by 30.0 cm of alumina. Calculations show that the addition of the alumina reflector doubles the epithermal neutron intensity at the irradiation port. A 0.05 g/cm2 thick layer of 6Li was placed between the beryllia moderator and the alumina reflector to reduce the number of thermal neutrons escaping from the beryllia to the alumina, and therefore the capture gamma rays produced by aluminum in the reflector. Also, a 0.025 g/cm2 thick layer of 6Li was placed at the irradiation port of the moderator assembly to remove thermal neutrons from the field. Finally, a neutron shield of 10.0-cm-thick D2O wrapped with 6LiF was placed around the moderator assembly except at the irradiation port. The useful neutron flux (which is the flux of neutrons with energies greater than ∼1 eV) at the irradiation point, which is in front of the moderator assembly, is 4.87 x 108 n/cm2.s for a 10-mA proton beam. The corresponding total absorbed dose rates for neutron and gamma rays are 1.9 and 0.64 cGy/min, respectively. The ratio of the total neutron absorbed dose rate to the useful neutron flux is 6.5 x 10-11 cGy/n·cm-2, which is slightly higher than, but comparable to, the value of this ratio that has been estimated for moderated reactor neutron fields. The maximum usable depth (MUD) in a head phantom is calculated to be ∼7.5 cm assuming that the 10B concentration is 30 µg/g in tumor and 10 µg/g in blood, and the singlesession treatment time is 1.6 h. If the beryllia cylinder in the moderator assembly were replaced by a 15.0-cm-high x 12.5-cm-radius cylinder of heavy water, the treatment time would be reduced to 30 min, at the price of a higher entrance neutron dose to normal tissue and thus lower therapeutic gains and MUD.
