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Thermal Hydraulics
The division provides a forum for focused technical dialogue on thermal hydraulic technology in the nuclear industry. Specifically, this will include heat transfer and fluid mechanics involved in the utilization of nuclear energy. It is intended to attract the highest quality of theoretical and experimental work to ANS, including research on basic phenomena and application to nuclear system design.
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2024 ANS Winter Conference and Expo
November 17–21, 2024
Orlando, FL|Renaissance Orlando at SeaWorld
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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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New laws offer nuclear industry incentives for existing power plant uprates
This year, the U.S. nuclear industry received a much-needed economic boost that could help preserve operating nuclear power plants and incentivize upgrades that extend their lifespan and power output.
Signed into law in 2022, the Inflation Reduction Act offers production tax credits (PTCs) for existing nuclear power plants and either PTCs or investment tax credits (ITCs) for new carbon-free generation. These credits could make power uprates—increasing the maximum power level at which a commercial plant may operate—a much more appealing option for utilities.
Francis Y. Tsang, Robert M. Brugger
Nuclear Science and Engineering | Volume 72 | Number 1 | October 1979 | Pages 52-64
Technical Paper | doi.org/10.13182/NSE79-A19308
Articles are hosted by Taylor and Francis Online.
The Doppler effect of 238U metal and 238U in U3O8 was studied by using beams of filtered neutrons at 24 ± 0.9 keV and 144 ± 12 keV from the University of Missouri Research Reactor (MURR) Facility. The Doppler effect is the broadening of the widths of the nuclear resonances in the total cross section due to the thermal motion of the nuclei. The effective average total cross sections (EATCS) for both kinds of samples were measured with good geometry transmission measurements as functions of sample thickness and temperature to show the Doppler effect. The temperature of the samples ranged from 38 to 1100 K. Temperature-related density effects were removed by simultaneously measuring the attenuation of gamma rays passing through the samples. The EATCS data as function of sample thickness at room temperature were fit with a nuclear cross section calculated from a ladder of resonances in the center-of-mass system. This ladder was generated from a set of synthesized nuclear parameters. The best fits to the cross sections, when extrapolated to zero thickness, give 13.5 ± 0.2 b at 24 keV and 11.9 ± 0.2 b at 144 keV. Our value at 24 keV agrees with the ENDF/B-IV, while our value at 144 keVis ∼4% greater. An ideal gas model including an effective mass, Meff, and an effective temperature, Teff, was used to Doppler broaden the calculated nuclear cross sections. With this model, good agreement was obtained to the EATCS data for all sample thickness at all temperatures with an Meff of 238 amu for the 238U metal and 400 amu for 238U in U3O8. The temperature dependence of Teff was determined by calculating the total energy using Debye frequency θv distributions. In these calculations, the Debye temperatures θD that provided the best fits were θD = 260 K for the metal and θD = 545 K for U3O8. These results indicate that this Doppler model combined with the calculated nuclear cross sections can provide a good fit to the data with a two-parameter system for the Doppler part, that is, θD and Meff for each state. From these EATCS data, estimates were made for the Doppler coefficient of a fast reactor. The estimate values of the Doppler coefficient have the right sign and magnitude to agree with Doppler Coefficients for particular fast reactor systems.