Development of the Uranium-236, Uranium-238 Signature for Pre-Detonation Nuclear Forensics

Project Overview

When nuclear material is found outside of regulatory control, a rapid, confident, and robust forensic assessment is often employed to determine the provenance of the material. Such investigations rely on multiple forensic signatures that provide complementary information about the origin and processing history of a sample. In this project, we developed a rapid method to measure 236U/238U in uranium ore concentrates (UOCs), which are among the most frequently trafficked nuclear materials. Uranium-236 is produced in U ores at ultra-trace levels. Therefore, Accelerator Mass Spectrometry (AMS) is required to measure 236U/238U in UOCs. As part of this work, we developed a method by which 236U/238U can be measured via AMS at Lawrence Livermore National Laboratory (LLNL). Multiple sample purification chemistries were tested, resulting in a rapid method that can allow for low-precision 236U/238U measurements within 4 hours of sample receipt; a more robust sample preparation method allows for more precise measurements within 24 hours of sample receipt.

We measured a suite of UOC samples from the Springfield UOC collection, which have been well-characterized via a variety of elemental and isotopic analyses. These existing data are being analyzed in conjunction with the new 236U/238U measurements to determine if the 236U/238U signature can provide predictive information about the neutron capture environment of the parent ore body.

Mission Impact

This work enabled the development of a new analytical method for rapidly measuring 236U in pre-detonation materials, which supports new and existing projects within Lawrence Livermore National Laboratory's Nuclear Threat Reduction /Forensic Science under the Threat Preparedness and Response Mission Area.The methods and expertise developed during this project have allowed for the start of new funded projects within the nonproliferation mission space.

Publications, Presentations, and Patents

Corinne Dorais, Scott J. Tumey, Naomi E. Marks, and Gregory A. Brennecka, "236U/238U measurements in uranium ore concentrates at CAMS" (Oral Presentation,15th International Conference on Accelerator Mass Spectrometry ANSTO, virtual, Nov 15-19, 2021).

Corinne Dorais, Naomi E. Marks, Gregory A. Brennecka, and Scott J. Tumey, "236U/238U measurements in uranium ore concentrates via accelerator mass spectrometry" (Poster Presentation, Methods and Applications of Radioanalytical Chemistry Conference - MARC, Kona, HI, April 3-8, 2022).