Experts: Dirty bomb would mostly cause panic

A "dirty bomb" is not to be confused with a nuclear explosion, but experts say such a device could release relatively small amounts of radiation over several city blocks and have its most devastating effect in the panic it probably would create.

For that reason, it has been called an ideal terrorist weapon.

A dirty bomb also is relatively easy to fashion. It can use a conventional explosive to disperse radioactive material.

Last month, the Nuclear Regulatory Commission disclosed that it receives an average of 300 reports a year of small amounts of radioactive materials missing from construction sites, hospitals and other users of these radioisotopes.

NRC officials said they have no evidence of anyone collecting this material to have enough for a dirty bomb. But critics say no one is sure of that.

The NRC has acknowledged that even a small amount of radioactive material, if properly milled into fine particles and dispersed by a conventional explosive, could spread radioactive particles over an area of several blocks.