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.
Stanley E. Turner, Thomas G. Haynes III
Nuclear Technology | Volume 169 | Number 2 | February 2010 | Pages 195-203
Technical Note | Radiation Protection | doi.org/10.13182/NT10-A9362
Articles are hosted by Taylor and Francis Online.
Neutron attenuation measurements have been used as an instrumental method of analyzing (normally flat) test coupons for the concentration of the 10B nuclide. Calibrated standards of well-characterized 10B content are used to interpret the observed neutron counting rates into the 10B areal density. Recently, there have been challenges to the validity of neutron attenuation measurements and their relationship to criticality safety analyses. For the most part, these challenges have been verbal without any supporting data. The present study was undertaken to provide experimental and analytical investigations of these challenges. The challenges are as follows: 1. It has been claimed that neutrons of any energy (including epithermal and fast neutrons) can be used for attenuation measurements. Spectral and reaction rate calculations are presented to demonstrate that only thermal neutrons have sufficient sensitivity to yield reliable neutron attenuation measurements because of the fundamental 1/v absorption cross section of 10B. 2. It has been alleged that only small-diameter [0.953 cm (3/8 in.)] neutron beams are acceptable for neutron attenuation measurements and that larger-diameter [2.54 cm (1 in.)] beams would "mask" any defects or significant nonuniformities. Both experimental and analytical data are presented to show that the measurements are independent of beam size and that adequate sensitivity to detect any defects or nonuniformities is provided. Criticality calculations are also presented to illustrate that small defects (holes or cracks) have very small effects on results of criticality analyses. 3. It has been postulated that in absorbers using particles of boron carbide, neutrons could stream past discreet particles, reducing the effectiveness of the absorber. While this may be true in attenuation measurements, there is no evidence that neutron streaming has any significant effect in criticality safety analyses. Calculations and an explanation are presented. Neutron attenuation and criticality analyses refer to physically different phenomena with appreciably different path lengths rendering criticality analyses insensitive to streaming.
