ONIX: An open-source depletion code with nuclear forensic application

Nuclear forensic interpretation is an unavoidable stage of the nuclear forensic process: it transforms the analytical results obtained at the stage of characterization into meaningful information useful for formulation of the nuclear forensic findings. As has been demonstrated by the ITWG's exercises CMX-1 and Galaxy Serpent 1 and 4, a capability to understand and use nuclear forensics signatures pertinent to nuclear material irradiated in a reactor is an important part of nuclear forensic interpretation process. It is also often required for operating a national nuclear forensics library. Nuclear depletion codes assist nuclear forensic interpretation by modelling the isotopic evolution of nuclear and non-nuclear materials through neutron irradiation and natural decay. Unfortunately, their proprietary nature and various export control regulations restrict the distribution of these codes, reduce the degree of transparency, and complicate the collaboration between groups from different countries which may be required in case of investigating a cross-border nuclear smuggling incident. The success of these collaborative efforts depends enormously on trust between the different parties involved and the transparency of the technologies used.