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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.
Joshua J. Jarrell, Marvin L. Adams, Joel M. Risner
Nuclear Technology | Volume 168 | Number 2 | November 2009 | Pages 424-430
Shielding | Special Issue on the 11th International Conference on Radiation Shielding and the 15th Topical Meeting of the Radiation Protection and Shielding Division (Part 2) / Radiation Protection | doi.org/10.13182/NT168-424
Articles are hosted by Taylor and Francis Online.
A widely used numerical method for discretizing the direction variable in the transport equation is the discrete ordinates technique. Here, we test various discrete ordinates quadrature sets on two three-dimensional (3-D) (X-Y-Z) shielding problems: the doglegged void neutron model and the pool critical assembly model. Commonly used quadrature sets, including the standard level symmetric sets and double Gauss-Chebyshev sets, produce significant ray effects associated with material discontinuities in both models. Abu-Shumays designed the quadruple range (QR) sets specifically for these types of problems and showed that they perform well in two-dimensional X-Y geometry. Here, we show that compared to more commonly used quadrature sets, the 3-D QR sets substantially reduce ray effects associated with material discontinuities in 3-D X-Y-Z discrete ordinates calculations.