Global Security Newswire

U.S. congressional auditors have noted various technical issues with a new generation of radiation detectors intended for U.S. points of entry and urged the Homeland Security Department to investigate possible improvements to detection machines already in place, according to congressional testimony yesterday by the Government Accountability Office (see GSN, Nov. 17).

The Advanced Spectroscopic Portal monitor systems continued to experience a high rate of "false positives" during July testing at the Nevada Test Site. The false alarm rate of the machines -- designed to spot potential nuclear- and radiological-weapon ingredients entering the country -- had been reduced by 69 percent, but that number fell short of the 80 percent reduction goal set by the department (see GSN, June 26).

In an attempt to address the high rate of false alarms, the Homeland Security Department has planned to decrease the sensitivity of the units. Computer simulations of the detectors suggest they would still be capable of detecting certain radiation sources more efficiently than current sensors allow. However, the Homeland Security Department's Domestic Nuclear Detection Office has not yet planned to conduct new tests of the devices operating at the reduced sensitivity level, GAO Natural Resources and Environment Director Gene Aloise told a House panel.

"By reducing the sensitivity to nuclear materials even further, it is uncertain exactly what improvement in detecting these materials the ASPs are providing or whether DNDO might be able to achieve a similar level of performance as the modified ASPs by improving the current-generation portal monitors that are already in place," says a summary of the GAO testimony.

Aloise also noted an instance during the July tests in which a detection unit erroneously turned off without alerting its operators. "As a result, were this not in a controlled testing environment, the [Customs and Border Protection] officer would have permitted the cargo to enter the country thinking the cargo had been scanned, when it had not," the document states.

The Homeland Security Department office has made plans to prepare for similar "critical failures," including the installation of warning lights on the machines, but customs officials emphasized the importance of improving the reliability of the machines to reduce such occurrences, according to the testimony.

The Domestic Nuclear Detection Office has not reported significant progress in studying an "energy windowing" process that could bolster the accuracy of present U.S. monitoring systems, the report adds.

Customs and Border Protection "officials stated that, depending on the outcome of this research, energy windowing could be the more cost-effective way to improve detection of certain nuclear materials," the GAO testimony reads. "In our view, ASPs being modified to diminish their capabilities to detect certain nuclear materials raises questions about whether energy windowing might be able to achieve a similar level of performance against these same materials from the [first-generation detectors] that are already in place" (Diane Barnes, Global Security Newswire, Nov 18).