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The human factor in licensing and operating the next generation of nuclear plants
As human factors specialists working at the intersection of human performance and nuclear operations, we are witnessing one of the nuclear sector’s most significant transitions in decades. The emergence of small modular reactors, microreactors, and other advanced designs is reshaping the industry’s landscape. Digital instrumentation and controls, passive safety systems, and increased automation are creating opportunities for greater safety margins and more flexible operation. These same features also fundamentally redefine what it means to “operate” a nuclear plant. Interactions among human roles, automation, and passive systems shape how people maintain awareness, exercise judgment, and intervene when necessary. These developments affect both operational realities and the regulatory foundations on which nuclear safety is built.
Justin D. Talley, Seungjin Kim, Tangwen Guo, Gunol Kojasoy
Nuclear Technology | Volume 167 | Number 1 | July 2009 | Pages 2-12
Technical Paper | NURETH-12 / Thermal Hydraulics | doi.org/10.13182/NT167-2
Articles are hosted by Taylor and Francis Online.
The present study investigates the geometric effects of a 45-deg elbow on the development and distribution of local two-phase flow parameters in horizontal bubbly flow. A round pipe with an inner diameter of 50.3 mm is used as a test section throughout the study. The test section consists of a 90-deg elbow followed farther downstream by a 45-deg elbow. Local two-phase flow parameters and pressure measurements are made at three different axial locations, one upstream and two downstream of the 45-deg elbow. In total, 15 different flow conditions are investigated for the present analysis. At the measurement port just downstream of the 45-deg elbow, the local parameters are acquired in both the vertical and horizontal directions along the radius of the pipe cross section to capture geometric effects of the flow restriction. The local two-phase flow parameters acquired in the present study include void fraction, bubble velocity, interfacial area concentration, and Sauter mean diameter. In view of one-dimensional transport, the local void fraction and interfacial area concentration are area averaged and plotted along the axial direction. The characteristic geometric effects of the flow restrictions are clearly demonstrated in the distribution of the two-phase flow parameters and pressure, as well as their development along the flow direction. The drastic changes in the interfacial area concentration across the elbow suggest that a 45-deg elbow induces significant changes in bubble interaction mechanisms.