The pagers, which can be worn on a belt, can "localize the source" of radioactivity through an audio tone, Boyd said.
Customs inspectors are also beginning to use the prototype of another device, a "radiation isotope identifier," he added, to detect neutron emissions.
There have been no incidents on the U.S. borders having to do with smuggled radioactive material destined for a weapon, Boyd said.
But the service supplies equipment, such as the radiation pagers, to foreign customs officers and trains them in their use. The U.S. Customs Service also trains foreign border guards in the techniques of finding smuggled missile parts and other weapons of mass destruction.
Boyd said Bulgarian border guards trained by the U.S. Customs Service and using U.S.-supplied pagers discovered uranium hidden in an air compressor in May 1999.
Even more significantly, U.S.-trained border guards in Uzbekistan, again using the Customs Service pagers, discovered 10 lead containers of radioactive material in March 2000.
The material, in a truck driven by an Iranian, was being transported from Kazakstan to an unknown destination in Pakistan, Boyd said.
Notable deaths of 2014 [PHOTOS]