Improving Detectability of HEU by Existing Radiation Detection Systems using Trace Addition of 232U to the Nuclear Fuel Cycle

We have assessed a method for incorporating ultra-trace levels of 232U into the low-enriched U nuclear fuel cycle to improve the detectability of high-enriched uranium (HEU) that might be produced. Computational assessment indicates that the addition of 232U as an Ore Processing Additive (OPRA) in the production of low-enriched uranium (LEU) fuels can enhance detectability of derived HEU to existing radiation detection systems operated around the world and without greatly impacting the production or use of LEU. The enhanced detectability stems from a combination of factors including the high-energy gamma emissions associated with 232U (daughters) and that 232U is preferentially concentrated relative to 235U during mass-based enrichment such as in a centrifuge cascade. OPRA represents a new approach to improving detectability of HEU, particularly shielded HEU, and could add to the range of methods to deter illicit HEU production and smuggling. This paper will review the many factors considered across the whole nuclear fuel cycle as a system including the production of 232U, implementation, and effects on operations. The work was performed as a collaboration between the Lawrence Livermore National Laboratory (LLNL), the Oak Ridge National Laboratory, the University of Tennessee at Knoxville, the University of California at Berkeley, and the University of Wisconsin-Madison. Exploration of the OPRA concept started as a LLNL Laboratory Directed Research and Development feasibility study and was then supported by the NNSA Office of Nonproliferation Research and Development. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC. - LLNL-ABS-831564.