Despite the more than $2 billion spent by the Department of Homeland Security on radiation detection devices, leading scientists tell ABC News the country remains wide open to terrorists who might try to smuggle nuclear material into the country. In a familiar scene at the port of Los Angeles today, senior U.S. officials demonstrated yet another new, expensive machine that supposedly can detect nuclear material hidden in shipping containers. The DHS has claimed this device is 95 percent accurate, and today Homeland Security Secretary Michael Chertoff had high praise for it. Photos Nuclear Material Bypasses Radiation Detection Devices at U.S. Ports in 2002 "This is great," he said. "This is the wave of the future." Despite Chertoff’s praise, a government investigation by the Government Accountability Office (GAO) concluded the new machines "fell far short of the 95 percent level of performance." Click Here for Full Blotter Coverage. At best, the GAO found the machines were 45 percent accurate, sometimes as low as only 17 percent accurate. "It is very frustrating when we pour billions of dollars into our homeland security, and yet we see so many of those dollars being wasted," Rep. Michael McCaul, R-Texas, the ranking member of the House Homeland Security Subcommittee on Emerging Threats, which has been a key oversight committee for the radiation detector program, said. That’s why Congress now wants a new round of tests before they will allow any more money to be spent on the system. "Today we learned that in fact it is riddled with inefficiencies that could in fact make it possible for al Qaeda to bring a nuclear bomb into a post in the United States," Congressman Ed Markey, D-Mass., said. It has been five years since ABC News first demonstrated the ease with which uranium, shielded in lead pipes, could be smuggled into the country in a shipping container, past supposedly state-of-the-art detection machines. But today leading scientists say the new machines are just as ineffective. "There are many, many ways of defeating the system," said Dr. Tom Cochran of the Natural Resources Defense Council, "and they are ways that would be known to people who know how to manufacture an improvised explosive device." In Los Angeles today, Secretary Chertoff acknowledged the need for more testing on this latest generation of equipment. "As we’re entering the field testing phase, we ought to kick the tires very hard," he said. Scientists say about the only real proven improvement in the new machines is a lot fewer false alarms. The old ones would go off if they detected kitty litter or bananas. That no longer happens, but they still can’t detect well-shielded nuclear bomb material. Do you have a tip for Brian Ross and the Investigative Team?