few terrorist groups, like Al Qaeda, have demonstrated the desire and the ability to cause mass death and destruction. Terrorists are influenced by their organization’s goals, which could involve achieving independence for a region such as Chechnya from a larger state such as Russia, spurring an apocalypse to cleanse the world of evil, or creating an Islamic caliphate, which would establish Islamic law throughout Muslim-majority countries. To achieve these goals, terrorists can use a variety of means, including improvised explosive devices, suicide bombers, airplane hijackings, or, in rare cases, unconventional weapons such as chemical, biological, radiological, or nuclear weapons. Most terrorist groups do not seek to cause mass death to accomplish their goals. Instead, weapons, such as RDDs, that would cause disruption, confusion, and mass panic could help gain notoriety for the terrorists and their objectives. A radiological terrorist attack would cause far less human and physical damage than a nuclear weapon. At the same time, it would highlight the terrorists' ability to obtain and use radioactive materials in a malicious way.

Radiological terrorism is a more attractive option than nuclear terrorism because of the relative ease with which a radiological weapon can be made and used. Nuclear terrorism requires obtaining or constructing a nuclear weapon that produces a nuclear explosion. Either of these options requires great technical expertise and access to high-security facilities. Making weapons out of chemical and biological materials also requires a fair amount of technical and scientific expertise although attacking relatively easily accessible tanks of hazardous chemicals used throughout the chemical industry could result in harmful effects. Radiological terrorism, on the other hand, involves using a radioactive source by itself, packaging radioactive material with a conventional bomb and exploding it in a public area, or attacking an already existing nuclear facility. Thus, although conducting an act of radiological terrorism is not easy, this option generally requires less expertise than most other forms of unconventional terrorism. Nonetheless, radiological attacks that would result in significant harm to health and damage to property would typically require advanced knowledge and skills.

Of the two types of radiological terrorism, use of a radiological device can be considered easier than attacking a nuclear facility. Successfully causing a large release of radiation through a terrorist attack on a nuclear power plant requires knowledge of the plant's physical design and layout, security measures, and weaknesses. It also demands either accurately attacking and damaging the core of the nuclear reactor or causing a sustained loss of coolant to the core, which is usually heavily shielded and protected by automatic shutdown functions and emergency cooling systems. This section will thus focus on the more likely terrorist option of use of a radiological weapon.

Radioactive materials are used everyday in many places throughout the United States and the world. Potential terrorists, therefore, may find it easier to gain access to these materials than those needed for chemical, biological, or nuclear terrorism. Exceptions include tanks of chlorine gas or other hazardous chemicals in the chemical industry and castor beans that can be relatively easily made into the biological toxin ricin. Radioactive sources are supposed to be regulated and well secured, but security measures may be different for each source and in each country where radioactive materials are stored. In addition, there are thousands of "orphan sources" located throughout the world. Orphan sources are radioactive sources that were lost, abandoned, stolen, or otherwise fell outside of regulatory control. These sources are outside of government control, and if found by or passed into the hands of terrorists, could be used for radiological terrorism.

The portability of certain types of radioactive sources also enhances the attractiveness of radiological terrorism. Radioactive sources differ greatly in size and level of radiation. Some sources may be relatively big and bulky because of the layers of shielding surrounding the radioactive material. The difficulty in moving these around may make these sources less attractive to terrorists. Other sources, however, are small enough to fit into your pants pocket or in the palm of your hand. For example, the tubes of cesium that were declared missing from a North Carolina hospital in 1998 were only three-quarters of an inch long by one-eighth of an inch wide.

What type of terrorist groups might be drawn to radiological terrorism? Given the relative ease with which a radiological weapon can be made and used, terrorist groups that lack a high level of technical and scientific expertise might find this type of radiological terrorism to be an attractive option. These lower-level capabilities also make it less likely that the groups will be monitored by intelligence and law enforcement agencies, thus increasing the risk posed by these groups. A radiological attack would likely result in mass panic, perhaps some human deaths and injuries, extensive physical and economic damage, and a great deal of attention for the terrorists themselves. Theoretically, this outcome might be considered ideal for groups that seek publicity for their name and their cause, without causing widespread devastation.