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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.
S. M. An, K. S. Ha, B. T. Min, H. Y. Kim, J. H. Song
Nuclear Technology | Volume 189 | Number 2 | February 2015 | Pages 133-142
Technical Paper | Reactor Safety | doi.org/10.13182/NT14-24
Articles are hosted by Taylor and Francis Online.
The ablation kinetics of special concrete, which has been developed as one of the candidate protecting materials for the EU-APR1400 ex-vessel core catcher, was investigated experimentally. Metallic corium and stainless steel melts were generated using an induction heating technique in a cold crucible and used for the interaction tests with the special concrete. The melt delivery system was designed to prevent the melt impingement effect and chemical changes of the concrete specimen owing to preheating during the melt generation process. The metallic corium melts above the activation temperature interacted with the concrete specimens very intensively, which led to an abrupt increase of concrete ablation. However, in the interactions with the steel melts, the concrete specimens were ablated slowly even though the melt temperatures were higher than the metallic corium melts. A postanalysis of the chemical compositions and microstructures of the ingot with the ablated concrete was performed to understand the ablation phenomena. It was found that the U and Zr contained in the metallic corium melt reacted with the oxygen released by the dissociation of ferric oxides in the special concrete above the activation temperature. As a result of the exothermic reaction, both the ablation rate and the reaction layer coefficient were increased with a higher melt temperature and exhibited higher values than those in the interactions with the steel melt. Moreover, it was verified that the oxidation quotients of U and Zr are higher than those of Fe and Cr.