Development Of Delayed Gamma-ray Spectroscopy For Nuclear Safeguards (3): Analytical Development And Capabilities

The Integrated Support Center for Nuclear Nonproliferation and Nuclear Security (ISCN) of the Japan Atomic Energy Agency (JAEA) is developing Delayed Gamma-ray Spectroscopy (DGS). DGS utilizes neutrons to induce fission in the sample followed by a measurement of gamma rays emitted by the fission products as they decay. The DGS analysis subsequently uses the ratio of the gamma-ray peaks to determine the relative fissile-nuclide contribution for composition evaluation, with integrated counts used to evaluate the fissile mass. This presentation focuses on the analysis being developed to efficiently analyze the gamma rays to evaluate both the composition and the mass to obtain the total fissile nuclide content in the sample. First will be a description of recent results obtained in collaboration with the European Commission Joint Research Centre about the interrogation timing sensitivity. Next, a description will be made regarding the present capability to determine the nuclide content important for safeguards evaluations when combined with the mass determination. Finally, a discussion will be presented on how these experiments affect the final development of the JAEA/ISCN DGS Monte Carlo for near-real-time analysis, including present uncertainty quantification.