Nuclear forensics

Overview

LLNL’s nuclear forensic capabilities provide critical data needed by decision makers when faced with possible illegal trafficking of radioactive material, or following a device detonation, when isotopic clues can help determine its cause and intended purpose. Identifying isotopic signatures in interdicted material provides insight regarding material origins, harvesting, and refinement, and supports efforts to prevent potentially catastrophic incidents involving radiological or nuclear materials.

LLNL’s AMS instruments enable researchers to measure isotope ratios that are much lower than what other analytical techniques can measure. As such, scientists can analyze signatures that would otherwise be undetectable. To exploit such signatures, they ionize samples to produce electrically charged particles, and then inject them into the CAMS accelerator, which destroys molecular interferences. Following the dissociation process, they measure ions of interest, such as aluminum-26 or beryllium-10, using highly sensitive particle detectors that allow them to distinguish these ions from other ions with the same atomic mass. This combination of molecular dissociation and particle identification enables researchers to measure ultra-trace concentrations of rare radionuclides that are present in an unknown sample.

Nonproliferation

Our research focuses on efforts to detect and deter illicit devices, including illegal trafficking of radioactive material. For example, we analyze material found in the environment, aiding efforts to prevent material from falling outside regulatory control. In addition, we analyze refined material and environmental clues associated with processing activities, which boosts our ability to detect covert development of nuclear devices and intercept material before it finds its way into a device.

For example, isotopic analysis using CAMS instruments enables us to distinguish between naturally occurring uranium and recycled uranium. We can also identify where natural uranium was harvested, providing insight regarding the pathway from mine to refined material. In addition, our ability to detect iodine in environmental samples provides clues regarding where plutonium reprocessing is taking place.

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Diagnosing debris

Researchers characterize debris produced by an explosion, providing clues regarding an explosion’s location and source, as well as the device design, origin, and intended purpose. For example, researchers use LLNL’s AMS tools to measure tiny traces of neutron activation products in the debris, aiding efforts to understand device design. They can obtain measurements using microgram-sized samples—an important capability when limited quantities are available for testing. And since minimal sample preparation is needed, researchers can obtain results within stringent response times.

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