By 2011, the department expects to have 1,400 of the next-generation screeners deployed at both ports and border crossings. The first 80 machines are scheduled to be installed this fall at the New York Container Terminal in Staten Island, N.Y.
Current radiological detection machines were installed after Sept. 11, 2001, as a shield against nuclear terrorism, a threat at the top of the nation's concerns, said Homeland Security Secretary Michael Chertoff.
The machines have screened 80 million cargo shipments entering the country since 2002, registering more than 300,000 false alarms.
"One of the problems that we have is the rate of false positives," Chertoff said.
Low levels of background radiation in harmless items often trigger the current machines. Kitty litter, granite and bananas have set the machines off.
The new detectors will range in cost from $350,000 to about $500,000 each, compared to the $180,000 for those currently employed. Officials, however, expect that the more-expensive systems will reduce the number of containers flagged for more-complete inspections each year from 821,000 to 15,000.
Using advanced computer software, the new devices will be able to better discriminate between different types of radioactive emissions, said Vayl Oxford, director of the Domestic Nuclear Detection Office.
The new technology is also to be deployed to ports abroad as part of the Energy Department's Megaports Initiative to secure shipping before it enters U.S. waters.
The Homeland Security Department also announced a plan to deploy the new devices in and around U.S. cities, and Oxford said work on a $3 million pilot deployment program has begun in New York City.
Officials are concerned not only about a devastating nuclear weapon, but also radiological "dirty bombs" that would use conventional explosives to disperse radioactive material. Such a weapon could render whole city blocks uninhabitable until the area could be decontaminated.
Radioactive material, such as isotopes used in medical applications, could be obtained within the country, incorporated into a dirty bomb and smuggled into a city without crossing a border.
"How do we protect cities, major urban areas in this country, from a nuclear or radiological bomb that was fabricated inside the country?" Chertoff asked.
In an urban context, the challenge is balancing the need for security with the need to keep traffic flowing, he said. "We don't want to set the red flags up every time someone sends a shipment of very respectable granite into the city."
The New York pilot program will allow officials to determine the range of the detection machines in the complicated context of an urban area with at least 150 points of entry. The success of the experiment in New York could shape the way the detection machines might be employed elsewhere.
"I think we need to take the lessons learned from a difficult and complex environment like New York and extrapolate them to other cities," Chertoff said.
Even with the next generation of machines, the detection capabilities to sniff out highly enriched uranium clad in certain kinds of radiation shields are not complete.
With the new technology, inspectors would only be able to detect "lightly shielded" uranium, Oxford said. His agency has received proposals for additional machines that would enhance the ability to detect shielded uranium, and Oxford said he expects to awards those contracts this fall.
Even with enhanced detection capabilities at certain U.S. points of entry, some experts have argued that securing long U.S. borders is exceedingly difficult. They point to preventing terrorists from getting their hands on nuclear material as a more pressing concern.
Trying to stop a terrorist with a nuclear weapon at the border is nearly impossible, Robert Gallucci said last month at a Russian American Nuclear Security Advisory Council discussion.
"Game over. There are just too many ways," said Gallucci, a former U.N. weapons inspector and now dean of the Edmund A. Walsh School of Foreign Service at Georgetown University.
Detectors are just one element in a larger architecture of defense, said arms control expert Michael Levi, a fellow at the Council on Foreign Relations.
"This is one of a large number of small elements that will add up to something significant," Levi told Global Security Newswire. "No one should think of this as a substitute for security at the source."
Keeping terrorists from nuclear material is "the most important and the most powerful defensive measure," he said.
Initial one-year contracts for the new detectors have been awards to Raytheon Corp., Thermo Electron Corp. and Canberra Industries.
"We think this is fulfilling a major capabilities gap we have in today in reducing the risk of nuclear and radiological threats," Oxford said.