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Radiological and Nuclear Detection Devices

Tyson Gustafson

Graduate Research Assistant, Center for Nonproliferation Studies

  • A truck passes through a radiation portal monitor at the port of Newark, New Jersey. A truck passes through a radiation portal monitor at the port of Newark, New Jersey.
    Source: www.whitehouse.gov
  • A Radiation Portal Monitor A Radiation Portal Monitor
    Source: http://rdnsgroup.pnl.gov
  • Spectroscopic Portal Monitor Spectroscopic Portal Monitor
    Source: http://rdnsgroup.pnl.gov

"The U.S. government's quest to defend the nation against a smuggled nuclear weapon or radiological "dirty" bomb is approaching a crossroads."[1] The government arrived at a critical juncture in early 2006 and was forced to choose the path to take with respect to radiological and nuclear detection devices. The choice was either to keep the older monitors that were proven but did still have their problems, or to upgrade to the new generation of monitors, despite the cost and the fact that they are unproven. Their decision: to allocate billions of dollars in contracts to upgrade to a new and improved system. This paper will look into the need for radiological and nuclear detection devices, examine the current and proposed systems, and finally review the budget for the program.

Introduction: Defining the Problem

Since the attacks of September 11th 2001, there has been an ever increasing focus on protecting America and its people from terrorist attacks. However, unlike several years ago, this protection is no longer limited to conventional weapons. A radiological and/or nuclear attack has become a serious threat, according to experts both within and outside of government, and this threat only continues to grow.[2] With an ever increasing number of countries and non-state actors seeking access to nuclear and radiological materials, the government has sought to create devices not only to deter attacks but to detect the basic materials needed for a radiological and/or nuclear attack. These devices will monitor major ports of entry in an effort to minimize the threat of an individual or group importing radiological and/or nuclear material into the United States. To put this into perspective, a recent exercise in the port of Los Angeles/Long Beach concluded that under the correct circumstances, a successful terrorist attack in the port could reach direct and indirect damages totaling $45 billion.[3] Currently, radiological and nuclear detection capabilities in the United States are limited, and some argue, ineffective. So what must a radiological and nuclear detection device entail?

There are a variety of views on this question; however the majority of them have been summed up by Nonproliferation, Homeland and International Security (NHI), a Directorate at the Lawrence Livermore National Laboratory. NHI focuses on enhancing national and international security by providing expertise, analyses, and systems solutions to prevent the spread and/or use of WMD. According to NHI, what is needed is, "Ways to detect small sources within a large sea of natural background radiation and to do so in such a way that does not impede legitimate commerce and traffic flow. These systems must be suitable for real-world applications-portable, rugged, battery-powered, lightweight, inexpensive, and easy to use by nonexperts."[4]

Admittedly, it is simple to define the problem and propose an ideal solution, but it becomes a different issue when it comes to actual implementation, budgets, and politics. The main objective, as stated above, is to prevent terrorist use of a radiological and/or nuclear weapon. This can be accomplished in part through improved radiological and nuclear detection devices as well as improved procedures and response. Of course, the Department of Homeland Security (DHS) would much rather intercept this nuclear material abroad, and although there are currently projects addressing this need, they are still facing problems and cannot guarantee the prevention of the spread of nuclear and radiological material. One program currently in effect is the Megaports Initiative by the Department of Energy. "The Megaports Initiative supplements the Department of Homeland Security's Container Security Initiative (CSI) in its effort to safeguard global maritime trade by enhancing security at seaports worldwide in order to identify and examine high-risk containers as early as possible before they reach U.S. shores."[5] However, as mentioned, they have thus far not proven 100% effective in preventing the spread of nuclear and radiological material. The upgraded system throughout the US ports would act as a second line of defense, improving chances of catching illicit radiological and nuclear material. The need for efficient and reliable devices is here; the question is can the call be answered?

Current monitors and future advances

Currently there are 884 Radiation Portal Monitors (RPM) that are monitoring the United States' land and sea ports of entry.[6] According to DHS reports, these monitors are able to inspect nearly 90% of the incoming cargo.[7] The exact percentage has been disputed but it should be noted that it is 90% of cargo that is deemed critical by the DHS, which is actually only 6% of all incoming cargo, leaving the great majority of containers and imports unchecked.

The Domestic Nuclear Detection Office (DNDO), under DHS, was "established to improve the Nation's capability to detect and report unauthorized attempts to import, possess, store, develop, or transport nuclear or radiological material for use against the Nation, and to further enhance this capability over time."[8] In June 2006, the DHS awarded the DNDO contracts totaling $1.15 billion to enhance the detection of radiological and nuclear materials. This funding will focus on the Advanced Spectroscopic Portal (ASP) RPM program. The current system uses a plastic scintillator for detection whereas the proposed upgraded detector will use sodium iodide or germanium. The next generation system will use "the spectra of radiation to improve system effectiveness by optimizing sensitivity, probability of detection, and false alarm rate."[9] Therefore, if the current RPMs are inspecting upwards of 90%, why is an upgrade needed? First, they are not inspecting 100% and that leaves room for error. In addition to this, current portal monitors are subject to false alarms caused by legitimate radioactive materials, (i.e. kitty litter, bananas, and ceramics). Evaluations of various border scenarios have shown that nearly 80% of false alarms were triggered by such legitimate radioactive materials.[10] These false alarms not only slow down business but also reduce the sense of urgency among those who respond to them. Between May 2001 and March 2005, there were reportedly 10,000 false alarms.[11] Furthermore, "the cost of closing a single freight terminal at the port of New York has been estimated to be $500,000 per hour."[12]

ASPs are the next generation of radiation detectors. They are comprised of radiation sensors in addition to using advance threat identification algorithms.[13] These detectors use spectroscopy to detect and identify radioactive sources. Spectroscopy is a technique used to study the make-up of an object based on the light it emits.[14] ASPs are said to dramatically reduce false alarms while still providing the same if not better coverage as its predecessor. "The ASP utilizes a monitor that measures and analyzes the type and level of radiation, compares the results with pre-selected criteria, and alerts appropriate staff if the measured radiation exceeds the criteria."[15] However, in a memo dated October 17, 2006 from DNDO to Government Accountability Office (GAO), it was acknowledged that "performance tests of ASPs did not meet DNDO's performance assumption in the cost-benefit analyses of correctly identifying HEU 95% of the time it passes through portal monitors."[16] This performance assumption is based on both masked and unmasked HEU sources. According to the memo, DNDO officials chose to not include this information in their cost-benefit analysis and instead relied on the assumption that over time the 95% accuracy level could be achieved with this program in the future.

There are five different types of radiation emissions, four of which are monitored to detect radiological and nuclear material: alpha, beta, gamma, and neutron radiation. Alpha radiation is by far the least penetrating but can be very harmful if relatively substantial amounts of alpha emitting materials are ingested or inhaled into a body. It only travels a few inches and is not even able to penetrate clothing. Beta radiation is more penetrating than alpha radiation. Beta radiation can travel several feet and can penetrate some materials; however, some protection can be provided by clothing. Furthermore, it is able to penetrate human skin but just to the germinal layer, where new skin cells are made. Highly energetic beta radiation could pose a hazard to unprotected soft tissue such as eyes. Gamma radiation, also known as highly penetrating radiation, is extremely dangerous. It can penetrate clothing and human skin and only can be blocked by using dense materials. Neutron radiation is caused when a neutron exists outside of an atomic nucleus. This generally only occurs in nuclear fission or in high energy reactions of nuclei. It is also penetrating but can be shielded with water or concrete.

ASPs, like their predecessor, are able to detect both gamma (emitted by radiological materials which can be used in a dirty bomb, as well as naturally occurring radiological material in kitty litter, bananas, and ceramics, etc.) and neutron emissions (emitted by a limited number of materials, such as plutonium-which can be used in creating a nuclear weapon) in closed, moving vehicles, containers, and railcars. But concerns remain that the ASPs are too limited in their ability to detect highly enriched uranium, a weakly radioactive material that is easiest to use in an improvised nuclear device, i.e., a crude nuclear bomb.

The Budget

When it comes to the budget for these monitors, the cost is of course the main concern; however, the source of the funding is also important. The Domestic Nuclear Detection Office (DNDO) under the DHS had a budget of $334 million in 2006 that would increase dramatically to $536 million in 2007.[17] "Subtracting $178 million in procurement of nuclear detection devices for U.S. ports of entry and $30 million in management costs for the newly independent office would leave $328 million for R&D, up dramatically from $209 million in 2006 and just $123 million the year before."[18] In July 2006, DHS announced that it planned to spend up to $1.2 billion to buy new screening machines in the fight against nuclear and radiological material.[19] This contract was awarded to three different companies for a five year period, (Raytheon, Thermo Electron, and Canberra Industries). The first year will focus on testing and analysis of three different ASP technologies.[20] The current monitors being used cost $55,000 per unit, whereas the upgraded monitor will cost $377,000 per unit.[21] DNDO's mission is to "develop, acquire and support the deployment of a domestic nuclear detection system to detect and report any attempt to import or transport a nuclear explosive device, fissile material, or radiological material intended for illicit use."[22] Based on this statement of purpose, DNDO has easily received an annual budget increase to counter the ever increasing threat of WMD materials. One major reason for its increased budget comes from the previously mentioned cost-benefit analysis done in May of 2006 by DNDO itself.

The cost-benefit analysis was set up with three goals: (1) provide a robust defense against nuclear and radiological threats, (2) limit delays to commerce, and (3) provide a sound financial investment for the U.S. government.[23] However, since this analysis was completed, DNDO has received much criticism on its analysis, some charging that the analysis looked at only the benefits while others still say it is incomplete and unreliable. "However DNDO's cost-benefit-analysis only considered the benefits of ASPs ability to detect and identify HEU and did not consider ASPs ability to detect and identify other nuclear and radiological materials."[24] DNDO failed to follow its own testing report and protocols.[25] Furthermore, on October 17, 2006, the GAO issued a report that stated "DNDO's cost-benefit analysis does not provide a sound analytical basis for DNDO's decision to purchase and deploy new portal monitor technology."[26] With this information in mind, it is clear that the analysis does not include all costs and benefits for acquiring and deploying portal monitors and a re-evaluation and cost benefit analysis should be done prior to further spending.

How does one know the detectors being used are at the greatest possible detection level to justify the costs? This is one of the major issues being argued today. It is for this reason that tests and cost-benefit analyses are conducted. DHS has recently proposed testing the effectiveness of new radiological and nuclear detection devices. This test will take place in New York City. Monitors will be secretly and strategically placed around the city in hopes of detecting radiological and nuclear material. One issue that has been raised is whether these detection devices will provide the population with a false sense of security and in the end make the city more vulnerable. "Rather than a cost benefit analysis it might make more sense to do a cost effective analysis specifying a minimum standard of detection capability and assume a certain amount of resources is available to a port authority."[27]


Detection of radiological and nuclear material is an invaluable part of the overall strategy in the prevention of illicit trafficking and safety of the United States and its citizens. However, the urgency and necessity of this step should not be a reason for a lack of diligence on behalf of the government. There have been various proposals in solving the problem of detecting radiological and nuclear material. Some of these include an upgrade from the current system to ASPs while others propose prescreening cargo before it reaches the United States. There is obviously a need for better monitoring, and the United States now faces the challenge of deciding which solution will be most effective in stopping nuclear and radiological material while at the same time controlling the spending.


[1] Hsu, Spencer S. "U.S. Weighs How Best to Defend Against Nuclear Threats," Washington Post, 15 April 2006, www.washingtonpost.com.
[2] Smalling, John, "New Technology Gives Bombs Squads the Upper Hand in the Fight Against Radiological or Nuclear Terrorism," The Detonator Volume 31, Number 5. 19 March 2007, www.ortec-online.com.
[3] Donald C Masters, "Safe Ports: A Global Issue?" Homeland Security Innovation Association, www.hlsia.org.
[4] "Radiological and Nuclear Countermeasures," Nonproliferation, Homeland and International Security, Lawrence Livermore National Labs, 5 March 2007, www.llnl.gov.
[5] "Second Line of Defense Program," National Nuclear Security Administration, 19 March 2007, www.nnsa.doe.gov.
[6] "Maritime Cargo Security In The Age Of Global Terrorism," U.S. Customs and Border Protection, 4 January 2007, www.cbp.gov.
[7] Chertoff, Michael, United States Senate Homeland Security and Government Affairs Committee, 13 February 2007, http://hsgac.senate.gov.
[8] "Domestic Nuclear Detection Office," Department of Homeland Security, 19 March 2007, www.dhs.gov.
[9] Reichel, Howard, "Radiological and Nuclear Detection Programs," Domestic Nuclear Detection Office, 8 September 2006, www.nlectc.org.
[10] "Safety of Radiation Sources and Security of Radioactive Materials," IAEA, European Commission, Interpol, World Customs Organization, Duon, France, 14-18 September 1998, IAEA, www-pub.iaea.org. [11] Hsu, Spencer S., "U.S. Weighs How Best to Defend Against Nuclear Threats," Washington Post, 15 April 2006, www.washingtonpost.com.
[12] "High Resolution Detection Systems for Interdiction of Nuclear Material Trafficking," Ortec, 2 April 2007, www.ortec-online.com.
[13] Ing, Lianne, and Mark Russell, "Example of Successful Collaboration with Industry and Government: Advanced Spectroscopic Portal (ASP) Program," cenSSIS RICC, 2 October 2006. Ratheyon Integrated Defense Systems and Bubble Technology Industries, 5 March 2007, www.censsis.neu.edu.
[14] NASA, 18 July 1995, http://liftoff.msfc.nasa.gov.
[15] Tamsett, Jeremy, "A New Generation of Radiation Monitoring Portals (RMP): Are We Any Safer?" Homeland Security Innovation Association, www.hlsia.org.
[16] "Combating Nuclear Smuggling," United States Government Accountability Office, 17 October 2006, www.gao.gov.
[17] Koizumi, Kei, "R&D in the Department of Homeland Security," Advanced Science, Serving Society, 5 March 2007, www.aaas.org.
[18] Koizumi, Kei, "R&D in the Department of Homeland Security," Advanced Science, Serving Society, 5 March 2007, www.aaas.org.
[19] Lipton, Eric, "U.S. to Spend $1.2 Billion On Detecting Radiation," New York Times, 15 July 2006, http://select.nytimes.com.
[20] Communication with a nongovernmental security expert.
[21] "Combating Nuclear Smuggling," United States Government Accountability Office, 17 October 2006, www.gao.gov.
[22] "Budget-in-Brief Fiscal year 2006," Department of Homeland Security, 6 March 2007, www.dhs.gov.
[23] "Combating Nuclear Smuggling," United States Government Accountability Office, 17 October 2006, www.gao.gov.
[24] "Combating Nuclear Smuggling," United States Government Accountability Office, 17 October 2006, www.gao.gov.
[25] "Al-Qaeda's Political Warfare: Isolating America," ThreatsWatch, 31 October 2006, http://rapidrecon.threatswatch.org.
[26] Beckner, Christian, "GAO slams DNDO assessment of new radiation portal monitors," Homeland Security Watch, 17 October 2006, www.hlswatch.com.
[27] Communication with Dr. Donald C. Masters, Homeland Security Innovation Association, www.hlsia.org.

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This material is produced independently for NTI by the James Martin Center for Nonproliferation Studies at the Middlebury Institute of International Studies and does not necessarily reflect the opinions of and has not been independently verified by NTI or its directors, officers, employees, or agents. Copyright 2015.


In this 2007 article, Tyson Gustafson assesses the utility of spending billions of dollars to overhaul the current system of radiological and nuclear detection devices in the United States.

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