"We honestly think we are doing a very aggressive and excellent job in this area, but we have obviously more to do," McGaffigan said in an interview. "Our view is we don't want to lose any of them, and we are going to have cradle-to-grave controls as soon as we possibly can for high-risk sources."
He said the government was undertaking a first-ever inventory of who possesses radioactive materials and how much they possess.
The GAO questioned whether the NRC has moved fast enough to secure sealed sources -- devices that contain small amounts of radiological materials used in construction and hospitals.
"The number of sealed sources in the US is unknown because NRC and states track numbers of licensees instead of sealed sources," the GAO told the Senate in a report published in August.
Two universities told the GAO about security problems with nuclear materials, specifically cases in which doors to rooms with the materials had been found unlocked or open.
The congressional investigators found that many of the 114 universities that possess, from earlier experiments, the radiological material plutonium-239 have tried unsuccessfully to return it to the government. The Energy Department doesn't have enough secure storage space, the investigators said.
RSS