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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
Conference on Nuclear Training and Education: A Biennial International Forum (CONTE 2025)
February 3–6, 2025
Amelia Island, FL|Omni Amelia Island Resort
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
Senate committee hears from energy secretary nominee Chris Wright
Wright
Chris Wright, president-elect Trump’s pick to lead the U.S. Department of Energy, spent hours today fielding questions from members of the U.S. Senate’s committee on Energy and Natural Resources.
During the hearing, Wright—who’s spent most of his career in fossil fuels—made comments in support of nuclear energy and efforts to expand domestic generation in the near future. Asked what actions he would take as energy secretary to improve the development and deployment of SMRs, Wright said: “It’s a big challenge, and I’m new to government, so I can’t list off the five levers I can pull. But (I’ve been in discussions) about how to make it easier to research, to invest, to build things. The DOE has land at some of its facilities that can be helpful in this regard.”
Keisuke Okumura, Kojiro Nishina
Nuclear Science and Engineering | Volume 102 | Number 4 | August 1989 | Pages 381-390
Technical Paper | doi.org/10.13182/NSE89-A23649
Articles are hosted by Taylor and Francis Online.
By cell calculation with the SRAC code system, void reactivity is evaluated for a high conversion light water reactor tight lattice, with an emphasis on the breakdown of the void effect into component nuclides, nuclear reactions, and energy groups. The analysis is restricted to infinite lattices and deals with the consequence of neutron energy spectrum shifts caused by void.In a preliminary parameter survey over various fissile plutonium enrichments, a 7.5 % enrichment is found approximately to border the negative and the positive coefficients, when the moderator channel volume to fuel volume Vm/Vf is fixed at a typical value of 0.53. With this combination of the enrichment and Vm/Vf values fixed, the reactivity effect for an incremental void increase is analyzed in detail at low-void conditions (0 to 10%) and at high-void conditions (95 to 100%).At low-void conditions, the 238U contribution is negative by the capture increase in the kilo-electron-volt range, whereas the 240Pu and 242Pu contributions proved to be positive by the capture decrease in the 0.1- to 10-eV range. At high-void conditions, on the other hand, 239Pu makes a positive contribution, originating from (a) the fission increase in the 50-eV to 1-MeV range dominating over the fission decrease in the 10- to 50-eV range, and (b) the lower capture-to-fission ratio above 10 keV. Such a positive contribution of 239Pu is in contrast to the negative contribution of 235U in a highly voided pressurized water reactor lattice. Americium-241 generated by the decay of 241 Pu makes a positive contribution in both low- and high-void conditions. The breakdown of the void effect clearly illustrates the physical mechanism.
