“Thousands of these sources have been lost, stolen or abandoned,” said the report sent to Sen. Daniel Akaka, D-Hawaii, who had requested the GAO review. The radioactive materials are used in everything from medical devices and remote generators to oil drilling equipment and to power lighthouses and weather stations. The devices contain such radioactive isotopes as cobalt-60, cesium-137 and strontium-90 in encapsulated or sealed small amounts. But if terrorists obtained a large number of these devices, they could be used to fashion a “dirty bomb” that would explode like a conventional explosive, but would scatter radioactive dust and debris. While there is no danger of a nuclear explosion, terrorist experts have said a dirty bomb – though not likely to cause any deaths beyond those from the conventional explosion – could cause panic and result in an expensive cleanup. The GAO report said the U.S. program has focused on securing material at medical facilities, but has made little progress in assuring that other, sometimes more dangerous sources are secure. WASHINGTON – The Energy Department has not done enough in Russia and in developing countries to secure radioactive material that could be used to make a so-called dirty bomb, congressional investigators said Tuesday. A report by the Congressional Accountability Office said that over the past four years security has been improved at hundreds of sites containing radioactive material in 40 countries but “many of the highest-risk and most dangerous sources still remained unsecured.” The GAO, Congress’ investigative arm, said the government has spent $108 million since 2002 on securing such material – some of it abandoned, lost or in poorly guarded waste sites. But there has been “limited progress securing many of the most dangerous sources,” especially in Russia where radioactive material is used to power hundreds of small generators in remote sites, the report said. 160Want local news?Sign up for the Localist and stay informed Something went wrong. Please try again.subscribeCongratulations! You’re all set!