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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.
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ANS Student Conference 2025
April 3–5, 2025
Albuquerque, NM|The University of New Mexico
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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
Norway’s Halden reactor takes first step toward decommissioning
The government of Norway has granted the transfer of the Halden research reactor from the Institute for Energy Technology (IFE) to the state agency Norwegian Nuclear Decommissioning (NND). The 25-MWt Halden boiling water reactor operated from 1958 to 2018 and was used in the research of nuclear fuel, reactor internals, plant procedures and monitoring, and human factors.
Angelo Frisani, Yassin A. Hassan
Nuclear Technology | Volume 167 | Number 2 | August 2009 | Pages 304-312
Technical Paper | Thermal Hydraulics | doi.org/10.13182/NT09-A8965
Articles are hosted by Taylor and Francis Online.
The purpose of the present work is to study the flow leakage through postulated microchannels. In the framework of the leak before break, it is reasonable to assume that a detectable leak develops before a large break occurs. A large pressure difference may exist between the crack inlet and outlet; the fluid residence time is so brief that thermodynamic equilibrium conditions cannot be reached within the crack. Using RELAP5-3D system code, the modified Henry's homogeneous nonequilibrium model was adopted to simulate the fluid condition at the choked point. In channels with large L/DH, mechanical equilibrium between the phases is usually reached. On the other hand, because of the small residence time, thermal equilibrium may not be achieved. Thus, the critical flow through the crack is kinematically homogeneous, but thermodynamically in nonequilibrium conditions. In this investigation, various channel cross-flow areas were considered, each having a sensitivity study performed in reference to the wall roughness. In this approach it was possible to analyze the dependence of channel pressure drop as a function of the Reynolds number and wall roughness. For high values of the Reynolds number, the pressure drop showed very little influence of the Reynolds number over the fluid conditions inside the microchannel. On the other hand, the wall roughness strongly influences the channel pressure drop and, consequently, the critical mass flow rate through the crack. The RELAP5-3D wall friction correlation was compared with various available models in the literature, such as John et al. (1987), modified Karman, Nikuradse (1933), and Button et al. (1978). These correlations predict similar values for the friction factor.The RELAP5-3D model was also in agreement with modified Karman correlation for the studied wall roughness values. However, it underestimated the friction factor with respect to John's formula. This indicates that the crack critical mass flow rate predicted by RELAP5-3D is larger than that calculated using John's correlation.
