Radiation Detection Flawed, Say Scientists

By Matthew Harwood

An investigation into cargo security by two scientists published in Scientific American reports radiation detection technology will fail to alert government inspectors of highly enriched uranium (HEU) smuggled into the country by terrorists.

"Although some federal officials and government contractors claim that the technology will be effective," write Thomas B. Cochran and Matthew G. McKinzie, senior scientists at the National Resources Defense Council, "an analysis we have conducted shows that the machines will not reliably reveal HEU. Instead the government must place a much higher priority on efforts to identify and eliminate or secure known stock HEU, stopping the potential problem at its source."

In 2002 and 2003, Cochran and McKinzie helped ABC News internationally smuggle depleted uranium, which emits "a radiation signature comparable to that of " HEU, through radiation detectors at U.S. ports. (The Department of Homeland Security (DHS) said its detection system works and that it does not calibrate for the "fake stuff.")

During its investigations, ABC News tested the ability of DHS' first generation detector systems, known as radiation portal monitors (RPMs), to detect HEU. The primary problem with RPMs was that even if they could detect radiation, they also needed to discern the radiation emitted by harmless substances from the radiation emitted from dangerous substances. "The inability of RPMs to measure a source's characteristic radiation spectrum," notes Cochran and McKinzie, "however, leads inevitably to false alarms from background sources, and the false-alarm rate for the current monitors is problematically high."

As a solution to this problem, DHS announced in 2006 that it would buy hundreds of new second-generation radiation detectors, or advanced spectroscopic portal (ASP) machines, for over $1 billion. These machines supposedly can differentiate between harmless radioactive cargo and more sinister substances. The authors say even these machines will not sufficiently detect HEU, because terrorists would likely shield HEU, possibly wrapping it in lead, to absorb its radiation output and stymie any detection device. Other problems with ASP machines continue to mount, Cochran and McKinzie report.

Their ability to reliably sense shielded HEU was not demonstrated during classified trials at the U.S. Department of [Energy's] Nevada test site. Moreover, the ASP machines failed to function properly, when installed at the Port Authority of New York and New Jersey, as a result of software problems. Indeed, in November 2007 the Washington Post revealed that Homeland Security itself had questioned the machines’ effectiveness. According to the newspaper, in September 2006 auditors at the U.S. Government Accountability Office alleged that officials had greatly exaggerated the tools’ capabilities. Another investigation by the accountability office a year later found that officials had overseen compromised tests of the ASP system. After petitioning Congress to allocate funds for more ASPs, in October 2007 Homeland Security chief Michael Chertoff decided to postpone certifying the new ASPs and further production until problems were resolved.

Cochran and McKinzie worry that an overreliance on radiation detection at ports of entry, which they argue is flawed, will allow terrorists to smuggle small amounts of HEU into the United States over time, which will then be assembled into a crude bomb, that if detonated, could cause mass destruction on American soil.

Rather than rely on radiation detection at American ports of entry, the authors argue the government should concentrate more on "securing and eliminating HEU sources worldwide." The authors also advocate that the United States seek a global ban on the commercial use of HEU, which can be replaced with alternative substances.


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