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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.
T. E. Booth, K. C. Kelley, S. S. McCready
Nuclear Technology | Volume 168 | Number 3 | December 2009 | Pages 765-767
MC Calculations | Special Issue on the 11th International Conference on Radiation Shielding and the 15th Topical Meeting of the Radiation Protection and Shielding Division (PART 3) / Radiation Protection | doi.org/10.13182/NT09-A9303
Articles are hosted by Taylor and Francis Online.
Dxtran is a deterministic transport method typically used for increasing the sampling in a spherical region that would otherwise not be adequately sampled because the probability of scattering toward the region is often very small. Essentially, the dxtran method splits the particle into two pieces at each source or collision point: a piece that arrives (without further collisions) at the dxtran sphere and a piece that does not. One difficulty with the dxtran method is that it can introduce a large weight fluctuation between particles colliding just before the sphere and particles colliding after crossing the sphere. New work shows that it is possible to mitigate this difficulty by extending the dxtran sphere concept to a set of nested dxtran spheres. Each dxtran sphere then shields its interior from particles whose weights are too large so that weights are more commensurate with their locations. Shielding against the large weights not only increases the efficiency of the calculation but the reliability as well. The effectiveness of the technique in MCNP was demonstrated on a 1-km air transport problem and on a concrete duct problem.