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
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
Utility Working Conference and Vendor Technology Expo (UWC 2024)
August 4–7, 2024
Marco Island, FL|JW Marriott Marco Island
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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Nuclear Science and Engineering
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August 2024
Fusion Science and Technology
Latest News
Taking shape: Fusion energy ecosystems built with public-private partnerships
It’s possible to describe fusion in simple terms: heat and squeeze small atoms to get abundant clean energy. But there’s nothing simple about getting fusion ready for the grid.
Private developers, national lab and university researchers, suppliers, and end users working toward that goal are developing a range of complex technologies to reach fusion temperatures and pressures, confounded by science and technology gaps linked to plasma behavior; materials, diagnostics, and electronics for extreme environments; fuel cycle sustainability; and economics.
A. C. Morreale, D. R. Novog
Nuclear Science and Engineering | Volume 164 | Number 2 | February 2010 | Pages 151-161
Technical Paper | doi.org/10.13182/NSE08-16
Articles are hosted by Taylor and Francis Online.
The pursuit of more realistic models for nuclear power plant systems is becoming increasingly important and has led to an expansion in statistical uncertainty analysis coupled with the use of best-estimate predictions. Within these methodologies, derived acceptance criteria have been developed to ensure that the ultimate safety criteria are met with acceptably high levels of probability and confidence. The meeting of these derived criteria with a probability of 95% for a confidence interval of 95%, the 95/95 criteria, ensures consistency between analysis and instrumentation accuracy requirements set forth in ISA 67.04 standards. However, the application of these statistical methods to accidents requiring operator intervention, such as complete loss-of-feedwater events, has not previously been the topic of investigation. This paper applies the extreme value statistics (EVS) methodology to the steam generator-level transients predicted to result from a total loss-of-feedwater accident and compares the result to other uncertainty propagation methods and deterministic calculations. The transient was modeled using a full-circuit one-dimensional thermal-hydraulic code, and the epistemic and aleatory uncertainties inherent in the reactor are assessed. Based upon these results the available steam generator inventories at the time of trip were statistically determined, and subsequently, the available times for operator action were determined. Comparisons were made between the EVS methods and limiting deterministic analysis results for a standard CANDU 9 design as well as to other best-estimate and uncertainty-analysis techniques. Key uncertainties were identified based on phenomena identification and ranking tables and were confirmed through sensitivity studies. The requirement for operator-initiated actions for the EVS case was ˜46 min with 95% probability and 95% confidence from the time of annunciation, and this was 30 min longer than the limiting deterministic case.