A RDD consists of a conventional high explosive device as the vehicle for propelling and scattering radioactive material. It should not be considered an atomic bomb or a nuclear weapon. Dan McBride, former director of the National Terrorism Preparedness Institute and currently senior faculty member of Kaplan College's Terrorism and National Security Management Certificate Program, believes that all of the known thefts of radioactive source material in recent years would barely be sufficient to construct one good RDD. Even if exploded, however, Steve Fetter, physicist and public policy professor at the University of Maryland, does not consider "dirty bombs" a serious threat in terms of deaths or illnesses beyond that posed by any high explosive. The primary concern would be irrational panic, stress, and associated illnesses, as well as economic losses in the area of the explosion. First responders to any explosion should have direct-read instrumentation to determine the presence and strength of any radioactivity. Threshold levels should be established and linked to appropriate responses to reduce risk; however, standards for radiation detectors/monitors for first responders have yet to be established, although their development is in process. In the interest of prevention, numerous instruments can detect radioactive materials. U.S. Customs and Border Protection (CBP) already uses a range of technologies at the Nation's ports to scan high-risk incoming shipments, with some designed specifically to detect nuclear/radioactive materials. Other devices can detect trace explosives, which would be present in a dirty bomb. Still, gaps in security are significant, and "weak, easily shielded and potentially hazardous sources exist and will remain difficult to detect," according to Fetter.