Border Security: Investigators Successfully Transported Radioactive Sources Across Our Nation's Borders at Selected Locations [open pdf - 135KB]
"This report responds to your request that we investigate potential security weaknesses related to the installation of radiation detection equipment at U.S. ports of entry. Based on discussions with your staff, we focused our efforts on testing whether the radiation portal monitors installed at the U.S. ports of entry would detect radioactive material transported in vehicles attempting to enter the United States. We also agreed to provide our observations regarding the procedures that Department of Homeland Security U.S. Customs and Border Protection (CBP) inspectors followed when the radiation portal monitors detected such material. We have reported on the security of our nation's northern border in terms of detection of illegal transport of radioactive material into the United States in our previous work."
Government Accountability Office (GAO): http://www.gao.gov/