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
Aerospace Nuclear Science & Technology
Organized to promote the advancement of knowledge in the use of nuclear science and technologies in the aerospace application. Specialized nuclear-based technologies and applications are needed to advance the state-of-the-art in aerospace design, engineering and operations to explore planetary bodies in our solar system and beyond, plus enhance the safety of air travel, especially high speed air travel. Areas of interest will include but are not limited to the creation of nuclear-based power and propulsion systems, multifunctional materials to protect humans and electronic components from atmospheric, space, and nuclear power system radiation, human factor strategies for the safety and reliable operation of nuclear power and propulsion plants by non-specialized personnel and more.
Meeting Spotlight
2025 ANS Annual Conference
June 15–18, 2025
Chicago, IL|Chicago Marriott 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
May 2025
Jan 2025
Latest Journal Issues
Nuclear Science and Engineering
July 2025
Nuclear Technology
June 2025
Fusion Science and Technology
Latest News
High-temperature plumbing and advanced reactors
The use of nuclear fission power and its role in impacting climate change is hotly debated. Fission advocates argue that short-term solutions would involve the rapid deployment of Gen III+ nuclear reactors, like Vogtle-3 and -4, while long-term climate change impact would rely on the creation and implementation of Gen IV reactors, “inherently safe” reactors that use passive laws of physics and chemistry rather than active controls such as valves and pumps to operate safely. While Gen IV reactors vary in many ways, one thing unites nearly all of them: the use of exotic, high-temperature coolants. These fluids, like molten salts and liquid metals, can enable reactor engineers to design much safer nuclear reactors—ultimately because the boiling point of each fluid is extremely high. Fluids that remain liquid over large temperature ranges can provide good heat transfer through many demanding conditions, all with minimal pressurization. Although the most apparent use for these fluids is advanced fission power, they have the potential to be applied to other power generation sources such as fusion, thermal storage, solar, or high-temperature process heat.1–3
Donald E. Parks
Nuclear Science and Engineering | Volume 9 | Number 4 | April 1961 | Pages 430-441
Technical Paper | doi.org/10.13182/NSE61-A25907
Articles are hosted by Taylor and Francis Online.
The principal result of the work reported in this paper is a first-order differential equation for the neutron spectrum in an energy region where the effects of chemical binding are significant but not dominant. Solutions of the differential equation provide accurate results for the spectrum in the cases of moderation by hydrogen, as well as by the heavier moderators, such as beryllium and graphite. In the derivation of the results, no restrictions are made concerning the nature of the motions of the moderator atoms. Interference effects in the neutron scattering are, however, neglected. The integral properties of the scattering kernel, which are found to influence the spectrum significantly, are calculated by means of the short-collision-time approximation, first introduced by Wick to compute the effects of chemical binding on slow neutron-scattering cross sections. Finally, for heavy moderators the representation of the energy-transfer properties of the moderator in terms of a first-order differential operator are combined with the P1 approximation to give a useful description of the spatially dependent spectrum.
