ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
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Division Spotlight
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.
Meeting Spotlight
2024 ANS Winter Conference and Expo
November 17–21, 2024
Orlando, FL|Renaissance Orlando at SeaWorld
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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Latest News
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.
K. D. Lathrop
Nuclear Science and Engineering | Volume 119 | Number 1 | January 1995 | Pages 80-86
Technical Notes | doi.org/10.13182/NSE95-A24071
Articles are hosted by Taylor and Francis Online.
The cosine of the laboratory scattering angle is derived for a neutron elastically scattering from a nucleus moving with a specified velocity. Scattering is assumed to be isotropic in the center-of-mass system, and the mean cosine of the laboratory scattering angle is calculated and shown to agree with the first Legendre moment of a scattering probability function derived by Blackshaw and Murray. Isotropic neutron-nucleus encounters are further assumed, and a second average is taken to calculate a mean cosine as a function of the neutron-nuclear speed ratio. This mean cosine approaches 2/(3m), where m is the nucleus mass relative to the neutron mass, as the neutron speed becomes large compared with the speed of the nucleus, but for m > 1, the scattering becomes more anisotropic as this speed ratio decreases before approaching isotropy at small neutron-nucleus speed ratios. This single nuclear speed mean cosine is compared with its average over a Maxwellian distribution of nuclear speeds. The two are qualitatively very similar. Taking the single nuclear speed to be the average speed of the Maxwellian distribution gives better quantitative agreement, in a least-squares sense, between the single-speed mean cosine and the Maxwellian average mean cosine than does using the most probable speed of the Maxwellian distribution.