“How much nuclear material is present and what is its probable intended use?” That is the central question faced by the inspectors of the International Atomic Energy Agency (IAEA), recently encountered by twelve U-M graduate students during a weeklong course hosted at Oak Ridge National Laboratory (ORNL) in early November.
Nuclear sites worldwide implement a series of protocols designed to provide transparency to their nuclear activities. These protocols are referred to as “nuclear safeguards.” Safeguards are applied to locations such as fuel preparation and storage facilities and nuclear power stations. In each of these facilities, the IAEA, through verification of properly implemented safeguards, must ensure that all nuclear material is present in its declared configuration.
The enrichment process is most commonly subjected to nuclear safeguards. Enrichment takes naturally occurring uranium and increases the concentration of uranium-235 (U-235), the type of uranium that readily undergoes fission chain reactions. In nature, only 0.7% of uranium is U-235. Nuclear power reactors use fuel that is approximately 5% U-235 while weapons applications require uranium that is greater than 90% U-235. Therefore, properly applied safeguards must not only verify the amount of uranium in a facility, but also its enrichment. This problem is profoundly challenging given that many of these facilities contain sensitive processes that the host country does not want to fully reveal. The IAEA works directly in this tension of transparency and secrecy.
The course offered a unique opportunity for U-M students to critically apply the tools of nuclear safeguards in realistic scenarios. While security restrictions preclude tests with enriched uranium samples on the U-M campus, the Safeguards Laboratory at ORNL has access to samples covering the full range of enrichments. The students at the course measured and characterized nuclear material with tools identical to those that IAEA field inspectors use to verify nuclear activities at sites around the world. They were able to analyze these samples in a variety of configurations, many of which were known only to the organizers.
The trip to ORNL was funded by the United States Department of Energy National Nuclear Security Administration and organized as a part of the “Nuclear Safeguards” course, taught bi-annually by Sara Pozzi, an associate professor of nuclear engineering and radiological sciences.
Shaun Clarke contributed this story.