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The Radiation Protection and Shielding Division is developing and promoting radiation protection and shielding aspects of nuclear science and technology — including interaction of nuclear radiation with materials and biological systems, instruments and techniques for the measurement of nuclear radiation fields, and radiation shield design and evaluation.
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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
Henry A. Sandmeier
Nuclear Science and Engineering | Volume 9 | Number 2 | February 1961 | Pages 260-270
doi.org/10.13182/NSE61-A15608
Articles are hosted by Taylor and Francis Online.
To test reactor fuel elements for their content of fissionable material and poison, it is desirable to have an assembly which has maximum sensitivity to a perturbation of fissionable absorber in the axial center line of the reactor. For normal sizes of thermal power reactor fuel elements, a graphite-moderated reactor is a suitable choice. The change in reactivity measured is the difference between the effect of changes in the fission and absorption parameters. For a bare core and uniform fuel distribution, maximum sensitivity to a fission-parameter-perturbation is obtained for a reactor which has a minimum critical mass. Maximum sensitivity to an absorber-parameter-perturbation is obtained for a reactor which has a minimum amount of total absorptions. Both the fission and absorption sensitivity reach a maximum when the critical mass is minimum. For a reflected core and uniform fuel distribution, the sensitivity to a fissionable absorber can be increased 22% over the bare core sensitivity. By introducing an internal and external reflector, the sensitivity to a fissionable absorber can be increased 30% over the externally reflected core and 56% over the bare core. For nonuniform fuel distribution, an expression is derived relating the effect of a perturbation in fission and absorption to reactivity. The problem of finding a fuel distribution ψ(r) to maximize this expression is analytically formulated. A parameter study was made for the same reactors as for the uniform fuel distribution cases. This was done by shifting more fuel towards the center or towards the edge of the core. No gain in fissionable absorber sensitivity was observed for either the bare or the externally reflected cores. However, the internally and externally reflected core showed a 10% increase in fissionable absorber sensitivity when more fuel was shifted towards the center.
