RPMs are the primary means by which CBP  scans cargo and vehicles at U.S. ports of entry for nuclear and  radiological material. 1.) RPM alarms can result from naturally occurring radioactive materials  (NORM), which are often emitted from certain consumer and trade goods,  such as ceramics, fertilizers, and granite tile. RPM alarms from NORM  are termed “nuisance” alarms by DHS and require CBP officers to spend  time determining that the source of the alarm is NORM and not nuclear or  radiological threat materials before the cargo container or vehicle can  leave the port. However, because of limitations in the design of  the plastic panels in the Ludlum RPMs that DHS acquired, these RPMs  cannot be upgraded with the revised operational settings and thus do not  have the threat discrimination capabilities equal to the upgraded Leidos  RPMs. As of August 2016, 100 percent of cargo containers and vehicles entering  land border crossings and nearly 100 percent of cargo containers passing  through seaports are scanned by RPMs, according to DNDO. DHS Changed Its Assessment of the Condition of the RPM Fleet and Consequently Altered Its RPM Replacement Strategy During Fiscal Years 2014 and 2015, DNDO Used a 13-Year RPM Service Life Estimate to Plan and Budget for RPM Replacements

DHS’s assessment of its RPM fleet shifted over time, and as a result DHS  has changed the focus of its RPM replacement strategy. However, recent DNDO studies indicate the fleet can remain  operational until at least 2030, with proactive maintenance and sufficient  availability of spare parts, so DHS has refocused its strategy on selective  replacements to improve efficiency. The budget justification  stated that funding increases would address sustainability of aging RPMs  and ensure compliance with the SAFE Port Act as DHS formulates a  long-term strategy for the replacement of RPMs at the end of their life  cycle. DHS’s Recent Assessments Indicate the Fleet Is Sustainable, and DHS Has Shifted Its Replacement Strategy to Focus on Efficiency

According to DHS data, as of August 2016, DHS’s RPM fleet remains  almost 100 percent operational, even as almost 20 percent of the RPMs  have reached the end of their original estimated 13-year service life and  another 40 percent are within 2 years of that date. DHS Plans to Replace RPMs at Selected Ports of Entry to Gain Operational Efficiencies

DHS plans to replace legacy RPMs at selected ports of entry with RPMs  that have greater threat discrimination capabilities to gain operational  efficiencies and reduce labor needs while continuing to meet detection  requirements. Specifically, from fiscal year 2016 through fiscal year 2018,  DHS is planning to replace more than 120 Ludlum RPMs at northern U.S.  land border crossings with upgraded Leidos RPMs from existing  inventory. GAO Recommended That the Department  of Homeland Security (DHS) Examine Use  of Optimization Techniques to Maximize  Radiation Portal Monitor (RPM) Potential  In 2009, we examined DHS’s Domestic  Nuclear Detection Office’s (DNDO)  development and testing of a new type of  RPM and, among other things, found that  DNDO had not completed efforts to fine-tune  the current fleet of RPMs to provide greater  sensitivity to threat materials. Beginning in 2014,  DHS’s U.S. Customs and Border Protection  (CBP) took action to upgrade some of its  RPMs by optimizing RPM threshold settings. During fiscal years 2018 through 2020, DHS is planning to replace  upgraded Leidos RPMs at selected high-volume ports of entry with  between 150 and 250 enhanced, commercially available RPMs that have  even greater ability to discriminate between NORM and materials that  pose a threat. According to DNDO and CBP officials, the improved threat  discrimination offered by these new, enhanced RPMs will further reduce  nuisance alarms and may enable high-volume ports of entry to implement  remote RPM operations. However, the data indicate that some high- volume ports of entry have lanes with higher nuisance alarm rates. Agency Comments and Our Evaluation

We provided a draft of this report to DHS for review and comment. DHS  provided technical comments that we incorporated, as appropriate. In addition, this report will be  available at no charge on the GAO website at http://www.gao.gov.
Why GAO Did This Study

Preventing terrorists from smuggling nuclear or radiological materials to carry out an attack in the United States is a top national priority. Terrorists could use these materials to make an improvised nuclear device that could cause hundreds of thousands of deaths and devastate buildings and other infrastructure. DHS's fleet of almost 1,400 RPMs helps secure the nation's borders by scanning incoming cargo and vehicles for radiological and nuclear materials. DHS began deploying RPMs to seaports and border crossings in fiscal year 2003. As RPMs began to approach the end of their expected 13-year service lives, DHS raised concerns over the sustainability of the fleet, the ability to maintain current scanning coverage, and the need for fleet recapitalization.
GAO was asked to report on the sustainability of the RPM fleet. This report provides information on (1) DHS's assessment of the condition of its RPM fleet and how, if at all, that assessment has changed over time; and (2) DHS's plans for meeting detection requirements in the future. GAO reviewed agency documentation, analyzed data on RPM age and condition, and reviewed budget justifications. GAO interviewed DHS officials and officials from a national laboratory on the current status of the RPM fleet and DHS's plans for future RPM acquisitions.
GAO is not making recommendations in this report. DHS provided technical comments on a draft of this report. These comments are incorporated as appropriate in the final report.

What GAO Found

The Department of Homeland Security's (DHS) assessment of its fleet of radiation portal monitors (RPM)—large, stationary radiation detectors through which vehicles and cargo containers pass at ports of entry—shifted over time and, as a result, DHS has changed the focus of its RPM replacement strategy. During fiscal years 2014 and 2015, as some RPMs began to reach the end of their estimated 13-year service life, DHS began planning for replacing the entire fleet of almost 1,400 RPMs. However, as of September 2016, the fleet remains nearly 100 percent operational and recent studies indicate that the fleet can remain operational until at least 2030 so long as proactive maintenance is carried out and RPM spare parts remain available. As a result, in 2016, DHS changed the focus of its RPM replacement strategy to selective replacement of RPMs—using existing RPMs that have been upgraded with new alarm threshold settings or purchasing enhanced, commercially available RPMs—to gain operational efficiencies and reduce labor requirements at some ports.
During fiscal years 2016 through 2018, DHS plans to replace approximately 120 RPMs along the northern U.S. border with upgraded RPMs and, during fiscal years 2018 through 2020, plans to replace between 150 and 250 RPMs at select high-volume ports with enhanced, commercially available RPMs. Specifically, DHS plans to replace some legacy RPMs—those that cannot be upgraded with the new alarm thresholds—at northern U.S. land border crossings with RPMs from existing inventory that have been upgraded. This upgrade enables improved threat discrimination and minimizes “nuisance” alarms created by naturally occurring radioactive materials (NORM) in commonly shipped cargo such as ceramics, fertilizers, and granite tile. Improved discrimination between NORM and threat material will create efficiencies for the movement of cargo through ports and minimize time that DHS's Customs and Border Protection (CBP) officers spend adjudicating the nuisance alarms. DHS is also planning limited replacement of upgraded RPMs at select high-volume ports with enhanced, commercially available RPMs that offer nuisance alarm levels significantly lower than even the upgraded RPMs. Currently, upgraded RPMs at some high-volume ports do not reduce nuisance alarm rates enough to implement remote RPM operations—which allows CBP officers to carry out other duties at the ports when not responding to an RPM alarm—because of the high number of vehicles and cargo containers passing through the ports daily.