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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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October 2024
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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.
W. W. Marr, M. M. El-Wakil
Nuclear Science and Engineering | Volume 41 | Number 2 | August 1970 | Pages 271-280
Technical Paper | doi.org/10.13182/NSE70-A20713
Articles are hosted by Taylor and Francis Online.
A serial (discrete-time continuous-space) method is employed to solve the unsteady-state energy equations in porous systems on a hybrid computer. The nonlinear, coupled partial-differential equations are solved by replacing the time derivatives with backward finite-difference approximations. To increase the order of accuracy in the time increment of the solution, the Crank-Nicholson scheme is used. The resulting difference-differential equations are solved in the direction opposite to that of the fluid flow to eliminate computational instability. The average temperatures over the consecutive time steps are solved on the analog portion of the hybrid computer. Solutions of the present time step are obtained by combining the analog solutions with those of the previous time step stored in the digital computer. The commonly encountered, mixed boundary conditions are satisfied by using a steepest descent iteration scheme based on least-squares-error minimization. A so-called binary-search technique provides reasonable initial trial values from which the iteration process converges. The trial values are improved by making use of the parameter influence coefficients that are obtained by taking finite differences through a number of test runs at the beginning of the solution and are taken to be constant during the entire solution time. In most cases, the iteration process converges in two to three iterations per boundary value searched. Comparisons of the hybrid computer solutions agree with those obtained by other numerical methods on a digital computer within 1%.