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Undeclared uranium hitches a ride on cobalt exports from Congo, study says
Philippe (left) and Manzuk quantified the amount of uranium that has been exported from the DRC in cobalt shipments or left behind in the environment. (Photo: Joel Hallberg/UW–Madison)
Researchers at the University of Wisconsin–Madison and Princeton University have published a study in Nature Communications that calls attention to a blind spot in nuclear nonproliferation: The Democratic Republic of the Congo (DRC) has exported thousands of metric tons of uranium, and there is no accounting for where it has gone.
In partnership with Lighthouse Reports and the Financial Times, UW–Madison nuclear engineering professor and nuclear security expert Sébastien Philippe and Ryan Manzuk, a geologist and research fellow in Philippe’s group and at Princeton, conducted the study using countrywide mineralization and geochemical data.
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.