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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.
Sourena Golesorkhi, Blair P. Bromley, Matthew H. Kaye
Nuclear Technology | Volume 194 | Number 2 | May 2016 | Pages 178-191
Technical Paper | doi.org/10.13182/NT15-30
Articles are hosted by Taylor and Francis Online.
The pressure-tube heavy water reactor (PT-HWR) has excellent potential as an operational technology to exploit the use of thorium. Reactor core configurations of an existing PT-HWR design with thorium-based fuels were simulated using the DRAGON/DONJON reactor physics code suite. The ultimate goal of this work was to achieve a self-sufficient equilibrium thorium cycle with a fissile inventory ratio (FIR) greater than unity (FIR ≥ 1.0) by altering the fueling configuration and leaving the reactor model relatively unchanged from the existing 700-MW(electric)–class PT-HWR design. A further constraint was the license requirements limiting the maximum channel and bundle powers of existing PT-HWRs. To improve the breeding potential in the PT-HWR, heterogeneous seed and blanket core configurations were selected for assessment as opposed to using a homogenous core configuration with one single type of fuel. A number of bundle design concepts were modeled with DRAGON: A 24-element variant of the internally cooled annular fuel bundle was chosen for the seed fuel, and a conventional 28-element bundle was used for the blanket fuel. Two annular heterogeneous core configurations were considered: inner seed outer blanket (ISOB) and inner blanket outer seed (IBOS). Time-average and instantaneous power calculations were performed using DONJON. It was found that while the ISOB configuration could attain net breeding (FIR ≥ 1.0), the maximum channel and bundle powers exceeded the defined limits. When the reactor was derated to reduce these powers, the fuel cycle fell just below net breeding, although it did have a very high FIR. The IBOS configuration could meet the power limits without derating but was not self-sufficient. Despite not being net breeders, the FIR in both cases was very close to unity (0.986 to 0.995). Work is continuing to further optimize the fuel bundle concepts and core configurations and to achieve net breeding. Overall, the PT-HWR shows great promise for the current-generation implementation of the thorium fuel cycle.
