There has been an intense discussion on nuclear security issues in recent years within the professional nuclear community. Numerous incidents of unauthorized acquisition and possession of nuclear/radioactive materials show that nuclear security is still far from perfect. This chapter will consider the characteristics, functioning, and possible effects of such a device in comparison with other types of nuclear terrorism. This chapter considers three types of nuclear terrorism: an Improvised Nuclear Device (IND), a Radiological Exposure Device (RED), and a Radiation Dispersal Devices (RDD). An IND is a device intended to cause a yield-producing nuclear explosion. A RDD is a device in contrast to a nuclear explosive device specifically designed to employ radioactive material by dissemination. A RED is a device that causes harm without dissemination or dispersal of radioactive material. The SCRD irradiation capability is much higher than that of a RDD or RED with high-level radioactive isotopes.