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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.
Naphtali M. Mokgalapa, Tushar K. Ghosh, Robert V. Tompson, Sudarshan K. Loyalka
Nuclear Technology | Volume 194 | Number 3 | June 2016 | Pages 353-368
Technical Paper | doi.org/10.13182/NT15-106
Articles are hosted by Taylor and Francis Online.
A methodology is developed to measure the adhesion force and the work of adhesion between aerosols generated in very-high-temperature reactors (VHTRs) and interacting with structural materials. The method uses an interactive system of a silver particle interacting with Haynes 230 (H230) surfaces, compares the measured data with theoretical values, and uses an atomic force microscope in an air environment glove box with ambient temperature of 20.27°C and relative humidity of 34.97%. The adhesion force data are obtained for a silver particle interacting with H230 under four different surface conditions including “as received” and after oxidation for 5, 10, and 15 min, respectively. It was found that the JKR (Johnson-Kendall-Roberts) theory predicted values that were up to three orders of magnitude higher than the experimental data. In contrast, the inclusion of surface roughness from both the particle and H230 samples in the calculations produced results that are one order of magnitude higher than the experimental data. These comparisons provide insight into the significant influence that surface roughness has on adhesion force. A range of values of 0.02 to 0.3 μN was obtained from the adhesion force distributions of measured data that can be used as bounds on forces that can be produced in a silver-H230 interactive system.