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Division Spotlight
Operations & Power
Members focus on the dissemination of knowledge and information in the area of power reactors with particular application to the production of electric power and process heat. The division sponsors meetings on the coverage of applied nuclear science and engineering as related to power plants, non-power reactors, and other nuclear facilities. It encourages and assists with the dissemination of knowledge pertinent to the safe and efficient operation of nuclear facilities through professional staff development, information exchange, and supporting the generation of viable solutions to current issues.
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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Nuclear Technology
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.
Xi Huang, Xu Cheng, Walter Klein-Heßling
Nuclear Technology | Volume 196 | Number 2 | November 2016 | Pages 248-259
Technical Paper | doi.org/10.13182/NT16-67
Articles are hosted by Taylor and Francis Online.
Falling water films have been employed for passive containment cooling in several Generation III pressurized water reactor designs. In this paper, the lumped-parameter (L-P) containment code system COCOSYS with an advanced water film model is applied to evaluate the performance of a passive containment cooling system (PCCS) during accidents. Based on the recent work and with further modification, an integrated water film model is developed. The new model considers different flow regimes of a liquid film as it flows downward and is being evaporated. The integrated model has been adapted to the L-P code and then implemented into COCOSYS. The new model enables the containment code to capture previously neglected phenomena, including the behavior of film breakup due to the reduction in mass; the formation of rivulets; the change in coverage rate and the development of rivulets; the change of velocity distribution as well as film thickness by considering the interfacial shear stress created by countercurrent air on the film surface; the hysteresis of rivulets, i.e., the process of advancing or retreating, involving changes in contact angles; and the influence of waves on the film surface.
The new model is validated against existing test results and experimental observations in the authors’ recent work and is further modified in this paper taking into account the influence of waves and the processes of rivulet hysteresis. The model is then assessed based on test nodalization, and the expected phenomena are observed. Afterward, the new model is applied to evaluate the performance of PCCS film cooling employed in the AP1000 containment.
It is concluded that the original film model tends to underestimate the pressure loads due to the absence of film breakup, rivulet behavior, and shear stress models. The coverage rate, as a new factor captured in the new model, limits the evaporation rate and thus restricts the cooling efficiency of the falling film. The sensitivity analysis reveals that the contact angle and hysteresis phenomenon, which were not previously considered in the code, play significant roles in PCCS film cooling. The advancing contact angle of the rivulets is a decisive factor for the peak pressure, while the retreating contact angle is influential in the later phase of cooling. It can be inferred from the study that the ideal situation for PCCS cooling is that in which the water film is approaching complete dryout at the bottom of the containment. The newly developed liquid film model helps improve the accuracy and reliability of the simulation results.