Fig. 1. Typical detection scenario for illicit sources.Abstract-SMART (Simulation of MAritime Radiological Threats) is a package created for simplyfing the process of modeling the performance of detector systems for identifying special nuclear materials (SNM). It consists of a library of spectra, including evaluation benchmarks produced for these SNMs as well as naturally occurring radioactive materials (NORM), a graphical front end system for setting up simulations with GEANT4 or MCNPX, and analysis tools for retrieving spectra plots from the detector, as well as imaging for Compton and Coded Mask spectrometers.