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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
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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Latest News
Vogtle-3 shuts down for valve issue
One of the new Vogtle units in Georgia was shut down unexpectedly on Monday last week for a valve issue that has been investigated and repaired. According to multiple local news outlets, Georgia Power reported on July 17 that unit 3 was back in service.
Southern Company spokesperson Jacob Hawkins confirmed that Vogtle-3 went off line at 9:25 p.m. on July 8 “due to lowering water levels in the steam generators caused by a valve issue on one of the three main feedwater pumps.”
Uffe C. Bergmann, Simon Baumgartner, Roger Bieli
Nuclear Technology | Volume 183 | Number 3 | September 2013 | Pages 298-307
Technical Paper | Thermal Hydraulics | doi.org/10.13182/NT13-A19419
Articles are hosted by Taylor and Francis Online.
An overview is given of existing design criteria to prevent fuel cladding dryout and the methods used in boiling water reactor reload analysis to evaluate the impact of channel bow on margins in the critical power ratio (CPR). Potential weaknesses in today's methodologies are discussed. Westinghouse in collaboration with KKL and Axpo - operator and owner of the Leibstadt NPP - has developed an enhanced CPR methodology based on a new criterion to protect against dryout during normal operation and with a more rigorous treatment of channel bow. The new steady-state criterion is expressed in terms of an upper limit of 0.01 for the dryout failure probability per year. This is considered a meaningful and appropriate criterion that can be directly related to the probabilistic criteria setup for the analyses of anticipated operation occurrences and accidents.In the Monte Carlo approach, a statistical modeling of channel bow and an accurate evaluation of CPR response functions allow the associated CPR penalties to be included directly in the plant safety limit minimum CPR and operating limit minimum CPR in a best-estimate manner. In this way, the treatment of channel bow is equivalent to all other uncertainties affecting CPR. Emphasis is put on quantifying the statistical distribution of channel bow throughout the core using measurement data.The enhanced CPR methodology has been implemented in the Westinghouse Monte Carlo code McSLAP. The methodology improves the quality of dryout safety assessments by supplying more-valuable information and better control of conservatisms in establishing operational limits for CPR.The methodology is demonstrated with application examples from the introduction at KKL.