A requirement to track the material by serial numbers was scrapped in 1985 and in many cases monitoring has been left to state health officials, according to Rep. Ed Markey, D-Mass., co-chairman of a bipartisan congressional task force on nuclear nonproliferation.
Forty-eight states have at least one facility using radioactive materials and 17 states have at least one facility that uses more than 1 million curies of the material for irradiation or sterilization, Markey's office said. Nuclear experts say about 1,000 curies is viewed as a sizable radiation source.
The locations of the materials include industrial food and medical irradiation and sterilization units, hospitals and research institutions.
Concern about the security of radioactive materials used in medicine and industry increased this week with the announcement that an alleged terrorist, linked to al Qaeda, had been taken into custody, suspected of planning an attack using a radioactive bomb. The Justice Department said there was no indication that the suspect, Jose Padilla, ever obtained the radioactive material for such a device.
Markey asked the Nuclear Regulatory Commission to provide detailed information on the tracking and security of cobalt 60, used to irradiate food, and cesium 137, used to sterilize medical equipment.
"It's not clear that anyone tracks the material at all," Michal Freedhoff, a science adviser to Markey, said Tuesday.
A dirty bomb uses conventional explosives to disperse radioactive materials. Most nuclear experts say such an attack would cause radiation contamination over several city blocks, but probably no deaths from radiation because of the low doses as the material is dispersed.
But such an attack could unleash panic, said the experts, and have significant economic fallout. It would require lengthy cleanup, although these materials are fairly easily detected.
Markey asked the NRC for information on whether background checks are required for people handling shipments of radioactive materials to irradiation and sterilization facilities; what security measures are in place where the material is stored; and how frequently NRC or state officials inspect the facilities.
Meanwhile, the Nuclear Energy Institute, the nuclear industry's trade group, discounted the likelihood that a dirty bomb might be made from used reactor fuel kept at commercial or power plants or research facilities.
Used nuclear fuel assemblies are highly radioactive and under tight security, said NEI president Joe Colvin, adding that a terrorist probably would be killed by the radiation if he tried to use one as a weapon.
"Even if terrorists were able to gain access," said Colvin, "the fuel assemblies...(are) built in a way that would prevent terrorists from wrapping it around an explosive charge."