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
Radiation Protection & Shielding
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.
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.
M. E. Congdon, R. W. Albrecht
Nuclear Science and Engineering | Volume 39 | Number 2 | February 1970 | Pages 207-214
Technical Paper | doi.org/10.13182/NSE70-A21200
Articles are hosted by Taylor and Francis Online.
A set of fundamental equations for fluctuations about the mean neutron density is studied for a reactor-detector system in which the detector is treated as an integral part of the system. The reactor-detector system is described, mathematically, as a general Markov process, and expressions for various descriptive parameters are derived in a consistent manner within the context of the basic equations. The role of the general adjoint neutron density is discussed with special emphasis on the mean and second-moment functions, and a relationship between the second-moment equations similar to the relationship between first-moments (mean and its adjoint) is observed. The extension to higher moments is also noted. A reduction of the second-moment equations is carried out, without approximation, using a variational principle. This consistent reduction allows a definition of the parameters involved, especially a definition of the detector efficiency, through a comparison of this reduced form with the usual point-reactor equations. The parameters defined contain weighting functions dependent upon the number of detectors used in the experiment.