ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Explore membership for yourself or for your organization.
Conference Spotlight
2026 Nuclear Energy Conference & Expo (NECX)
August 24–27, 2026
Dallas, TX|Hilton Anatole
Latest Magazine Issues
Aug 2026
Jan 2026
2026
Latest Journal Issues
Nuclear Science and Engineering
September 2026
Nuclear Technology
Fusion Science and Technology
August 2026
Latest News
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.
Ahmad K. Al-Basheer, Glenn E. Sjoden, Monica Ghita
Nuclear Technology | Volume 169 | Number 3 | March 2010 | Pages 252-262
Technical Paper | Radiation Protection | doi.org/10.13182/NT10-A9377
Articles are hosted by Taylor and Francis Online.
Dosimetry problems inherently involve dose determinations among widely varying materials and densities, and may require complex, detailed investigations of the angular, spatial, and energy behavior of the applied radiation transporting throughout the simulation geometry. Traditionally, Monte Carlo codes have been implemented in solving these types of problems using voxelized geometries and phantoms. The motivation of this work is to investigate the discretization requirements for deterministic radiation transport simulations for these problems via direct solutions of the linear Boltzmann transport equation, focusing on the discrete ordinates (SN) method. The SN method can yield accurate global solutions, provided the inherent discretizations among the angular, spatial, and energy domains properly represent problem physics. In this paper, the SN approach is implemented using a three-dimensional (3-D) 60Co photon transport simulation to highlight the critical issues encountered in performing deterministic photon simulations in dosimetry problems. Calculations were performed using the PENTRAN parallel SN code to obtain a 3-D distribution of flux and dose computed using a collisional kerma approximation. For an acceptable result, we determined that a minimum angular Legendre-Chebychev quadrature of S32 with P3 anisotropy is required, with block-adaptive meshes on the order of 1 cm, even in air regions, implemented with an adaptive differencing scheme (implemented in the PENTRAN code) to yield optimal solution convergence. Also, photon cross-section libraries should be carefully evaluated for the problem studied; for our test problem, the BUGLE-96 photon library yielded the closest results to Monte Carlo (MCNP5) among those tested. Overall, this work details the levels of discretization involved in performing deterministic computations in dosimetry problems and will be useful in enabling future efforts to perform rapid deterministic computations of phantom doses.
