Terrorism potential for research reactors compared with power reactors - Nuclear weapons, "dirty bombs," and truck bombs

If terrorists could steal 25 kg to 50 kg of highly enriched uranium fuel to be used for one or more large research reactors, they might be able to make a nuclear weapon from it. The same is not true of unburned fuel from power reactors because the uranium is not highly enriched and therefore not useful for making such weapons without a difficult uranium enrichment process. If terrorists could steal radioactive fuel that has been burned in either kind of reactor they, could probably, make a radioactive dispersal device or "dirty bomb." If terrorists could use an airplane or truck bomb to crash through walls and fences protecting either kind of reactor and penetrate the reactor's containment or blow up in the pond where irradiated spent nuclear fuel is stored, they might be able to disperse radioactivity over an area the shape and size of which would depend not only on the effect of the crash or explosion but also on the direction and speed of the wind. The amount and degree of radioactivity of irradiated fuel is likely to be much greater in power reactors but the vulnerability of irradiated fuel is likely, to be greater in research reactors.