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
Operations & Power
Members focus on the dissemination of knowledge and information in the area of power reactors with particular application to the production of electric power and process heat. The division sponsors meetings on the coverage of applied nuclear science and engineering as related to power plants, non-power reactors, and other nuclear facilities. It encourages and assists with the dissemination of knowledge pertinent to the safe and efficient operation of nuclear facilities through professional staff development, information exchange, and supporting the generation of viable solutions to current issues.
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!
Latest Magazine Issues
Aug 2024
Jan 2024
Latest Journal Issues
Nuclear Science and Engineering
October 2024
Nuclear Technology
Fusion Science and Technology
August 2024
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.
Weston M. Stacey, Jr.
Nuclear Science and Engineering | Volume 40 | Number 1 | April 1970 | Pages 73-90
Technical Paper | doi.org/10.13182/NSE70-A18880
Articles are hosted by Taylor and Francis Online.
The multigroup neutron kinetics equations are derived and investigated for the case when the within-group weighting spectra, which are used in defining group constants, are space- and time-dependent. New terms are introduced by the space- and time-dependence of these weighting spectra. The derivation is carried through the hierarchy of operations by which the continuous space, time, and lethargy dependence is replaced by a discrete representation. The new terms do not alter the usual positivity properties associated with the discrete multigroup kinetics equations, provided that certain conditions are satisfied. Conditions are also established which are sufficient to ensure that the discrete representation is adjoint consistent; i.e., the discrete representation of the adjoint equation is mathematically adjoint to the discrete representation of the direct equation. A similar development is presented for the Spectral Synthesis approximation. Conditions are established for the adjoint consistency of the discrete representation. The type of positivity argument made for the multigroup equations is shown to be invalid for the Spectral Synthesis equations.