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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
International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2025)
April 27–30, 2025
Denver, CO|The Westin Denver Downtown
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
INL’s new innovation incubator could link start-ups with an industry sponsor
Idaho National Laboratory is looking for a sponsor to invest $5 million–$10 million in a privately funded innovation incubator to support seed-stage start-ups working in nuclear energy, integrated energy systems, cybersecurity, or advanced materials. For their investment, the sponsor gets access to what INL calls “a turnkey source of cutting-edge American innovation.” Not only are technologies supported by the program “substantially de-risked” by going through technical review and development at a national laboratory, but the arrangement “adds credibility, goodwill, and visibility to the private sector sponsor’s investments,” according to INL.
Jeffrey E. Seifried, Ehud Greenspan
Nuclear Science and Engineering | Volume 181 | Number 1 | September 2015 | Pages 82-95
Technical Paper | doi.org/10.13182/NSE14-104
Articles are hosted by Taylor and Francis Online.
An expression is derived for attributing the reactivity response due to perturbations to spectral, spatial, and isotopic effects. It is shown to be consistent at a global level with similar expressions derived in previous work but can provide more detailed information on the physics phenomena contributing to the reactivity response of the perturbation. Using this expression, the reactivity effect of local coolant density perturbations [local void coefficient of reactivity (VCR)] is studied for two reduced-moderation boiling water reactor (RBWR) core designs—the thorium-fueled RBWR (RBWR-Th) and the uranium-fueled RBWR (RBWR-AC)—as well as for a standard advanced boiling water reactor (ABWR). The RBWR core designs feature large axial variation in their neutron spectra.
The axial distribution of local VCR along the RBWR-Th seed and along the ABWR core were found to have the same general shape: negative throughout but most negative near the bottom and asymptotically approaching zero toward the top. However, the RBWR-Th VCR is roughly four times more negative. The RBWR-AC local VCR axial distribution varies greatly: it is very close to zero in the seed regions and has a significant positive component in the central blanket.
Three effects were identified as contributing to the VCR due to a local water density change in the lower part of the RBWR-Th seed: local spectrum hardening that tends to increase the local reproduction factor (ηr) of each of the fuel isotopes; a redistribution of the local neutron absorption between the fuel isotopes resulting in a shift of absorptions from higher to lower isotopic reproduction factors and, hence, to a reactivity loss; and an axial flux tilt across the core from axial zones of higher ηr to axial zones of lower ηr, which makes another negative contribution to the reactivity worth of the perturbation.