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Homeland Security

Radiation Portal Monitors (RPMs)

A radiation portal monitor is a detection device that provides Customs and Border Protection (CBP) with a passive, non-intrusive means to screen trucks and other conveyances for the presence of nuclear and radiological materials. These systems are capable of detecting various types of radiation emanating from nuclear devices, dirty bombs, special nuclear materials, natural sources, and isotopes commonly used in medicine and industry.

As the nation's primary border enforcement agency, CBP must do everything in its power to prevent terrorists and terrorist weapons, including weapons of mass destruction, from entering this country. CBP must fulfill this mission while simultaneously facilitating the flow of legitimate trade vital to the U.S. economy. As the events of September 11 have shown, new tactics and resources are necessary to defeat a more determined terrorist enemy. Nuclear and radiological materials are of particular concern because of their potential to harm large numbers of people and disrupt the U.S. economy. The deployment of portal monitors is an important component of CBP's multi-layered strategy to prevent the introduction of nuclear and radiological materials into this country.

CBP is installing these radiation portal monitors nationwide - at seaports, land border ports of entry and crossings, including rail crossings, international airports, and international mail and express consignment courier facilities in an effort to screen 100 percent of all incoming goods, people, and conveyances for radiation.

The radiation portal monitor does not produce images. Rather, the portal monitor is a passive system that captures and alerts to energy emitted by radioactive sources that happen to pass near it. The system is very similar to a radio receiver, in that it responds to certain types of energy and provides an indication to the operator of the strength of the energy received.

Portal monitors do not emit ANY radiation. They are completely safe for anyone passing by them, including children and pregnant women. Portal monitors are passive "detectors" of radiation, not emitters of radiation. Portal monitors are very common in hospitals and other industries. In hospitals, for instance, portal monitors are often used to ensure that radioactive materials are not improperly removed from the facility.

An alert by a portal monitor indicates that the device has detected a source of radiation passing by it. An alert by itself does NOT necessarily mean that a nuclear weapon or harmful radiation has been detected. There are many legitimate, "innocent" sources of radiation, including naturally occurring radiation and various medical and industrial isotopes that pose little threat to the public. Nevertheless, in the case of any alert by a portal monitor, CBP will follow strict protocols to determine whether the source of radiation is a potential terrorist threat, a natural source, or a legitimate medical/industrial source of radiation. Depending on the determination, CBP will take the appropriate action called for in its response plans.

As of 31 March 2006:

  • CBP has screened over 80 million containers with RPMs and has successfully resolved over 318,000 radiation alarms with little disruption to the normal flow of traffic.
  • 100 percent of all mail and packages entering the U.S. are screened for radiological materials.
  • Along the northern border, 80 percent of personal vehicles and 90 percent of commercial truck traffic is screened.
  • Deployed RPMs along the southern border allow screening of approximately 74 percent of personal vehicles and 88 percent of truck traffic entering from Mexico.
  • Additional RPM deployments at seaports are occurring every day with the current screening of all sea-borne containers entering the U.S. at 51 percent and is expected to grow to 65 percent by the end of September 2006.

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Page last modified: 13-07-2011 12:51:30 ZULU