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Isotopes & Radiation
Members are devoted to applying nuclear science and engineering technologies involving isotopes, radiation applications, and associated equipment in scientific research, development, and industrial processes. Their interests lie primarily in education, industrial uses, biology, medicine, and health physics. Division committees include Analytical Applications of Isotopes and Radiation, Biology and Medicine, Radiation Applications, Radiation Sources and Detection, and Thermal Power Sources.
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2025 ANS Annual Conference
June 15–18, 2025
Chicago, IL|Chicago Marriott Downtown
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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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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
S. N. Purohit
Nuclear Science and Engineering | Volume 9 | Number 3 | March 1961 | Pages 305-313
Technical Paper | doi.org/10.13182/NSE61-A25881
Articles are hosted by Taylor and Francis Online.
The time-dependent energy spectra, for times greater than the slowing-down time, were generated in a monatomic heavy gas with the help of a multigroup formalism. These spectra were obtained for the infinite as well as finite media of beryllium and graphite. The behavior of asymptotic energy spectra during the last stage of neutron thermalization and diffusion periods was studied. The thermalization time constant for the establishment of the final Maxwellian velocity distribution of neutrons, in a monatomic heavy gas, was estimated to be equal to (1.176ξΣs0υ0)−1. Total thermalization times for neutrons in beryllium and graphite were found to be equal to 114 and 238 µsec, respectively. Using the energy-dependent transport mean free path, the diffusion cooling coefficient for beryllium was calculated to be equal to 0.890 cm2 For graphite, under the constant diffusion coefficient assumption, the diffusion cooling coefficient was determined to be equal to 1.922 cm2.
