# “Dirty Bombs”: Technical Background, Attack Prevention and Response, Issues for Congress

> Briefs, arguments, decisions, and more.

URL: https://www.frixlaw.com/law-library/documents/crs%3AR41890

## Record

- **Collection:** Congressional research report
- **Document type:** CRS Report
- **Published:** June 24, 2011
- **Citation:** R41890

## Text

“Dirty Bombs”: Technical Background, Attack
Prevention and Response, Issues for Congress
Jonathan Medalia
Specialist in Nuclear Weapons Policy
June 24, 2011

Congressional Research Service
7-....
www.crs.gov
R41890

CRS Report for Congress
Prepared for Members and Committees of Congress

“Dirty Bombs”: Technical Background, Attack Prevention and Response

Summary
Congress has long sought, through legislation and oversight, to protect the United States against
terrorist threats, especially from chemical, biological, radiological, and nuclear (CBRN) weapons.
Radiological dispersal devices (RDDs) are one type of CBRN weapon. Explosive-driven “dirty
bombs” are an often-discussed type of RDD, though radioactive material can also be dispersed in
other ways. This report provides background for understanding the RDD threat and responses,
and presents issues for Congress.
Radioactive material is the necessary ingredient for an RDD. This material is composed of atoms
that decay, emitting radiation. Some types and amounts of radiation are harmful to human health.
Terrorists have shown some interest in RDDs. They could use them in an attempt to disperse
radioactive material to cause panic, area denial, and economic dislocation. While RDDs would be
far less harmful than nuclear weapons, they are much simpler to build and the needed materials
are used worldwide. Accordingly, some believe terrorists would be more likely to use RDDs than
nuclear weapons. Key points include:
•

RDDs could contaminate areas with radioactive material, increasing long-term
cancer risks, but would probably kill few people promptly. Nuclear weapons
could destroy much of a city, kill tens of thousands of people, and contaminate
much larger areas with fallout.

•

Cleanup cost after an RDD attack could range from less than a billion dollars to
tens of billions of dollars, depending on area contaminated, decontamination
technologies used, and level of cleanup required.

•

Terrorists would face obstacles to using RDDs, such as obtaining materials,
designing an effective weapon, and avoiding detection.

Governments and organizations have taken steps to prevent an RDD attack. Domestically, the
Nuclear Regulatory Commission has issued regulations to secure radioactive sources. The
Department of Homeland Security develops and operates equipment to detect radioactive
material. The National Nuclear Security Administration (NNSA) has recovered thousands of
disused or abandoned sources. Some state and local governments have taken steps to prepare for
an RDD attack. Internationally, the International Atomic Energy Agency has led efforts to secure
radioactive sources. Its Code of Conduct on the Safety and Security of Radioactive Sources offers
guidance for protecting sources. The G8 Global Partnership has secured sources in Russia and
elsewhere. A State Department program strengthens border security. Other nations and nongovernmental organizations have acted to secure sources as well. Key points include:
•

Nuclear Regulatory Commission actions have done much to instill a security
culture for U.S. licensees of radioactive sources post-9/11.

•

Many programs have sought to improve the security of radioactive sources
overseas, but some incidents raise questions about security.

Should prevention fail, federal, state, and local governments have taken many measures to
respond to and recover from an RDD attack. The National Response Framework “establishes a
comprehensive, national, all-hazards approach to domestic incident response.” The federal
government has resources for recovery. Key points include:

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“Dirty Bombs”: Technical Background, Attack Prevention and Response

•

Government agencies have done much to prepare for and recover from an RDD
attack. This work would help cope with other disasters. Conversely, planning for
other disasters would help in the event of an RDD attack.

•

Some experts have raised questions about the effectiveness of planning to
respond to and recover from an RDD attack.

This report raises several issues for Congress, including:
•

the priority for countering RDDs vs. other CBRN;

•

the priority given to securing domestic vs. overseas radioactive sources;

•

whether to establish a radiation detection system in cities;

•

how best to prepare for decontamination following an RDD attack;

•

how to dispose of potentially large volumes of waste generated by
decontamination;

•

whether to modify certain personnel reliability standards;

•

whether to modify the pace of a program for implementing certain security
enhancements for U.S. radioactive sources; and

•

how to improve radiological forensics capability.

CRS Report R41891, ”Dirty Bombs”: Background in Brief, by Jonathan Medalia, is an abridged
version of this report.

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Contents
Introduction...................................................................................................................................... 1
Overview: Congress and “Dirty Bombs”......................................................................................... 2
A Note on Terminology ............................................................................................................. 3
Radiation and Radiological Dispersal Devices................................................................................ 4
Radiation and Its Effects............................................................................................................ 4
RDDs and Nuclear Weapons ..................................................................................................... 9
Value of RDDs for Terrorists................................................................................................... 10
The Threat: Feasibility, Fear, Probability, Impediments.......................................................... 11
Area Contaminated by an RDD Attack and Cost to Decontaminate ....................................... 15
Preventing an Attack...................................................................................................................... 17
Domestic Efforts...................................................................................................................... 17
Securing Radioactive Sources........................................................................................... 18
How Secure Are Radioactive Sources in the United States?............................................. 24
Detecting Radioactive Sources.......................................................................................... 28
Intelligence and Counterterrorism..................................................................................... 29
Global Efforts .......................................................................................................................... 30
Securing Radioactive Sources........................................................................................... 30
How Secure Are Radioactive Sources in Other Nations? ................................................. 37
Attack Response, Recovery, and Attribution ................................................................................. 41
Organization and Planning for Response ................................................................................ 41
Response.................................................................................................................................. 45
Recovery.................................................................................................................................. 48
Attribution ............................................................................................................................... 51
Lessons .................................................................................................................................... 55
Difficult Metrics ............................................................................................................................ 56
Budget ..................................................................................................................................... 56
Probability of an RDD Attack ................................................................................................. 57
Impact of an Attack ................................................................................................................. 57
Issues for Congress ........................................................................................................................ 58
Legislation ..................................................................................................................................... 62

Figures
Figure 1. A Possible RDD Attack on Washington, DC.................................................................... 8
Figure 2. Area Contaminated by an RDD Attack .......................................................................... 16
Figure 3. Area Contaminated to Various Levels, and Resulting Costs .......................................... 17
Figure 4. Iris Reader ...................................................................................................................... 21
Figure 5. Radiation Detector.......................................................................................................... 21
Figure 6. Foundations of Radioactive Source Security ................................................................. 40
Figure A-1. Gamma-Ray Spectra of Cobalt-60 and Cesium-137 .................................................. 67
Figure A-2. Radiation Exposure Pathways from an RDD ............................................................. 70

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Figure A-3. Cesium Chloride......................................................................................................... 72
Figure A-4. Cobalt ......................................................................................................................... 72
Figure A-5. A Possible RDD Attack on Washington, DC .............................................................. 74
Figure A-6. A Sealed Source.......................................................................................................... 80

Tables
Table 1. Differences Between Nuclear and Radiological Forensics .............................................. 55
Table A-1. Radionuclides and Quantities of Concern Regulated by NRC .................................... 76
Table B-1. Some U.S. vulnerabilities to RDDs based on 2009 testimony of Kenneth
Sheely, NNSA, updated with 2010 comments by NNSA........................................................... 81

Appendixes
Appendix A. Technical Background .............................................................................................. 64
Appendix B. Some U.S. Vulnerabilities to RDDs ......................................................................... 81

Contacts
Author Contact Information........................................................................................................... 83

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Introduction
In one nightmare scenario, a terrorist “dirty bomb” spreads radioactive material across dozens of
square miles, causing panic in the target area and beyond, costing tens of billions of dollars to
remediate, costing further sums in lost wages and business, compelling the demolition and
rebuilding of contaminated buildings, forcing difficult decisions on how to dispose of
contaminated rubble and decontamination chemicals, and requiring people to relocate from areas
with elevated levels of radiation.
But in other scenarios, a terrorist plot fails. Security measures keep terrorists from obtaining
radioactive material. Terrorists use a weakly radioactive material that causes little contamination.
They obtain too little material to be effective, or so much that it kills them before they could
attack. Equipment detects the material overseas, at U.S. borders, or inside the United States.
Material disperses over a small area, facilitating cleanup, or so widely that much of the area
would not require decontamination. Some blows out to sea. Such factors as weather, form of
material, and degree of remediation required affect cleanup cost by several orders of magnitude
and greatly reduce the damage that terrorists could expect to cause. Terrorist awareness of such
failure paths might deter an attack.
Radiological dispersal devices (RDDs) may be explosive-driven—a dirty bomb—or use
nonexplosive means like a crop duster airplane. Radioactive material may be dispersed indoors to
contaminate a building, though the scenario most commonly discussed involves detonation of a
dirty bomb outdoors. Because of their potential disruptive effects, legislation includes RDDs as
one type of weapon of mass destruction (WMD), along with chemical, biological, and nuclear
weapons,1 and a U.N. commission in 1948 included “radio active material weapons” as a form of
WMD.2 Congress has been deeply involved in efforts to protect the United States and other
nations against terrorist attacks, especially since 9/11.
The large range of possible effects of radiation results in widespread misunderstanding of the
characteristics and effects of RDDs, especially when augmented by fear of radiation that has
existed for over a half-century. To address these and related problems, this report provides
background on RDDs and issues they raise; it does not track policy actions concerning RDDs in
detail. It attempts to help understanding of these weapons in order to aid Congress in its oversight
and funding of programs to counter them.3 Understanding the threat that an RDD attack poses
1
The Intelligence Reform and Terrorism Prevention Act of 2004, P.L. 108-458, includes these four types of weapons in
its definition of weapons of mass destruction; see 6 U.S.C. 485 (a) (6).
2
Commission for Conventional Armaments, resolution defining armaments, U.N. doc. S/C.3/30, adopted at the 13th
meeting of the Commission for Conventional Armaments, August 12, 1948, in U.S. Department of State Bulletin,
August 29, 1948, p. 268.
3
Useful documents on RDDs include Roger Eckhardt, “Ionizing Radiation—It’s Everywhere,” Los Alamos Science,
no. 23, 1995, http://www.fas.org/sgp/othergov/doe/lanl/00326627.pdf; Charles Ferguson et al., Commercial
Radioactive Sources: Surveying the Security Risks, Center for Nonproliferation Studies, January 2003; U.S. Nuclear
Regulatory Commission, “Medical, Industrial, and Academic Uses of Nuclear Materials,” http://www.nrc.gov/
materials/medical.html; Gregory Van Tuyle et al., “Reducing RDD Concerns Related to Large Radiological Source
Applications,” September 2003, http://www.nti.org/e_research/official_docs/labs/LAUR03-6%202.pdf; Peter
Zimmerman with Cheryl Loeb, “Dirty Bombs: The Threat Revisited,” Defense Horizons, January 2004, pp. 1-11,
http://www.hps.org/documents/RDD_report.pdf; Charles Ferguson and William Potter, The Four Faces of Nuclear
Terrorism, Monterey, CA, Center for Nonproliferation Studies, 2004; Argonne National Laboratory, “Radiological
Dispersal Device (RDD),” Human Health Fact Sheet, August 2005, http://www.ead.anl.gov/pub/doc/rdd.pdf; K.G.
(continued...)

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and—of equal importance—the limits of that threat requires a brief discussion of the relevant
science. Subsequent sections of this report turn to RDDs, preventing an attack, and response to
and recovery from an attack. This report then offers observations and issues and options for
Congress. It compares RDDs and nuclear weapons but does not address chemical or biological
weapons. It is not intended as a comprehensive summary of the many domestic and international
programs that address the RDD threat in some way.

Overview: Congress and “Dirty Bombs”
Congress has demonstrated a sustained interest in the threat that RDDs pose to the United States
and other nations. It has enacted legislation pertaining to RDDs, held hearings on them, and
requested numerous reports from the Government Accountability Office (GAO). It has done so
for a number of reasons. Radioactive materials are used worldwide for medical, industrial,
research, and other beneficial purposes. Yet their security is far from airtight, especially in foreign
countries, as evidenced by many reports of trafficking and attempted trafficking. Terrorists could
create an RDD, though not necessarily an effective one, by stealing radioactive material and
detonating an explosive charge next to it. Preventing an RDD attack and preparing to respond to
and recover from an attack are thus matters of homeland security.
Terrorists, too, are interested in RDDs. An RDD has the potential to contaminate some square
miles (ranging from less than one to perhaps 100, depending on how one defines contamination)
with radioactive material. The attack could render an area off-limits for days to years, cause
significant economic disruption (e.g., by forcing the closure of a port or evacuating the center of a
city), cost tens of billions of dollars to remediate, impose further costs in lost wages and business,
force the demolition and rebuilding of contaminated streets and buildings, increase the cancer rate
over the long term, and cause panic and a climate of fear in the target area and far beyond.
Despite the seeming ease of launching a successful RDD attack, terrorists have not done so. The
reasons are necessarily speculative, but may include difficulties in handling radioactive material,
lack of sufficient expertise to fabricate material into an effective weapon, a shift to smaller-scale
but simpler attacks using standard weapons and explosives, and improved security.
Of course, such factors cannot guarantee that no attack will occur. Accordingly, the executive
branch, with congressional support and sometimes at congressional direction, has undertaken
many measures to reduce the likelihood of an attack. These include increasing the security of
radioactive material, augmenting counterterrorism efforts by intelligence and law enforcement
agencies, conducting “stings” to catch would-be terrorists attempting to purchase radioactive
material and those willing to sell it, and deploying radiation detectors worldwide. The
government has also made extensive plans for responding to and recovering from an attack.
Foreign governments and international organizations have taken similar measures, and some
nongovernmental organizations have provided resources and analysis in support of counter-RDD
efforts.
(...continued)
Andersson et al., “Estimation of Health Hazards Resulting from a Radiological Terrorist Attack in a City,” Radiation
Protection Dosimetry, vol. 131, no. 3 (2008), pp. 297-307, http://rpd.oxfordjournals.org/content/131/3/297.full; and
John Poston, Sr., et al., Management of Terrorist Events Involving Radioactive Material, report 138, National Council
on Radiation Protection & Measurement, 2001, summary at http://www.ncrppublications.org/Reports/138.

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The prospect of an RDD attack raises several issues for Congress, including:
•

the priority to be given to countering terrorism using RDDs vs. other types of
unconventional weapons;

•

the priority to be given to domestic vs. overseas expenditures to secure
radioactive sources;

•

whether to use federal funds to develop and deploy radiation detection networks
in major cities and elsewhere;

•

how best to prepare for decontamination following an RDD attack, such as the
balance between R&D, stockpiling of equipment and supplies, training, rapid
distribution of information, and analysis of the cost of decontamination vs.
demolition and reconstruction;

•

how to dispose of contaminated waste, including rubble from demolition and
chemicals from decontamination, following an attack;

•

whether to modify standards for permitting unescorted access to certain U.S.
radioactive sources;

•

whether to modify the pace of a program for implementing certain security
enhancements for U.S. radioactive sources; and

•

how to enhance U.S. capability for radiological forensics.

A Note on Terminology
Legislation, media reports, and the public use the term “weapon of mass destruction,” or
“WMD,” extensively to refer to chemical, biological, radiological, and nuclear (CBRN) weapons.
The term “WMD” is problematic from an analytic perspective, however, in that it lumps these
unconventional weapons together and implies that they are similar even though each type differs
greatly from the others in its mechanisms and effects. As a result, significantly different
approaches are required to address the threats that each type poses. The term is also unclear. For
example, does “destruction” refer to number of people killed, buildings destroyed, or economic
damage? If the reference is to number of people killed, the various types of “WMD” would differ
immensely. If “mass” refers to number of people killed, how many people constitute “mass”? If a
biological weapon killed five people, as the anthrax attacks did in 2001, would that weapon count
as a weapon of mass destruction, or would the threshold be, say, 5,000? As a result of these
difficulties, many analyses, and this report, refer instead to “CBRN,” which explicitly states the
types of weapons meant and avoids defining “mass” and “destruction.”

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Efforts to Negotiate a Radiological Weapons Convention
During World War II, in addition to developing nuclear weapons, the Manhattan Project considered the direct use of
radiological materials as a weapon. This concept of a “radiological weapon” (RW) is the same as that of a radiological
dispersal device (RDD). Development work on RWs continued after the war. During the Korean War, proposals
were advanced for laying down a barrier of radioactive material along the Chinese border, but RW development
appears to have ended by the mid-1950s.
In 1976, the Ford Administration identified the use of radioactive materials as a potential terrorist threat, and began
discussions with the Soviet Union to ban RWs and the use of radioactive materials in war even if not weaponized. In
1979, the United States and Soviet Union tabled elements of an RW Convention at the Committee on Disarmament,
and in 1983 the renamed Conference on Disarmament (CD) began multilateral negotiations on the Convention. In its
1983 report to the U.N. General Assembly, the CD included a draft RW Convention, with some provisions still to be
agreed. Negotiations were hampered by the issue of attacks on nuclear facilities. At least one delegation, Sweden,
considered this issue more important than radiological weapons, and gave little support to the Convention. Further,
when the CD’s 1984 session began, the Reagan Administration declined to actively pursue the negotiations because of
a concern that a convention might be seen as controlling nuclear weapons. The RW issue remains on the CD’s
agenda as part of the item “New types of weapons of mass destruction and new systems of such weapons;
radiological weapons.” However, it has not been accorded a high priority, and the CD is no closer to concluding a
Convention, or resolving the issue of attacks on nuclear facilities, than it was in 1983.
Provided by Pierce S. Corden, former RW lead officer on the U.S. CD Delegation, and currently a Visiting Scholar,
Center for Science, Technology and Security Policy, American Association for the Advancement of Science, February
17, 2011.

Radiation and Radiological Dispersal Devices
Radiation and Its Effects
This section provides a brief technical background; readers seeking detail should read Appendix
A instead. Many atoms are stable: they will remain in their current form indefinitely. Some atoms
are unstable, or radioactive. They “decay” or “disintegrate,” usually into atoms of a different
element, often through emission of various particles.4 Decay is often accompanied by emission of
gamma rays, a form of electromagnetic radiation, often of high energy. A radioactive atom is
called a “radionuclide”; that term refers to properties of individual atoms, while “radioactive
material” refers to bulk properties. Each radionuclide decays in a specific way. For example,
when uranium-235 decays, it emits alpha particles and gamma rays, mainly of low energy; cobalt60 emits beta particles and high-energy gamma rays when it decays. A unit called the curie (Ci)
measures radioactivity; 1 Ci = 3.7 x 1010 disintegrations per second.5 The time in which half the
atoms of a mass of a radioactive material decay is called the half-life.
Radiation strikes people constantly, but much of it, like light or radio waves, is harmless or nearly
so. Some high-energy radiation is “ionizing.” Most atoms have no net electrical charge because
they have an equal number of positively-charged protons and negatively-charged electrons.
Ionizing radiation knocks electrons off atoms, turning atoms into positively-charged ions that
damage living cells. Very low doses of radiation produce few if any effects, but progressively
higher doses may increase the risk of cancer or may cause radiation sickness or death. Effects
4

The most common types of particles emitted in decay are alpha particles (two protons plus two neutrons), beta
particles (an electron or positron, with the latter being a positively-charged electron), and, for heavy elements, neutrons.
5
The International System of Units uses a different unit, the becquerel (Bq), where 1 Bq = 1 disintegration per second.

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visible in individuals, such as nausea, are “deterministic”; their severity varies with dose. Effects
detectable in populations, such as increased incidence of cancer, are “stochastic”; their probability
varies with dose. In the United States, dose is usually measured in units of rem.6 This unit takes
into account the amount of radiation absorbed and its biological effects. The average dose for the
U.S. population is estimated at 620 millirem (mrem; 1,000 mrem = 1 rem) per year, about half
from medical sources and half from natural background.7 An RDD attack is likely to expose few
people to a dose of more than a few rem per year, even using the unrealistic assumption that they
remain in the affected area without sheltering for a year.
Any effects from a dose of a few rem per year are likely to be stochastic. Views differ on the
harm from that dose. One view is that any amount of radiation increases cancer risk; another is
that there is no evidence that radiation of less than about 10 rem per year increases that risk. The
U.S. Nuclear Regulatory Commission (NRC) uses the former approach to be conservative in
setting dose standards.8 Further, various standards imply different degrees of harm from a dose of
a few rem per year. For dose to the public resulting from the nuclear fuel cycle (e.g., nuclear
power plants), the Environmental Protection Agency uses a standard of 25 mrem per year of
whole-body dose.9 NRC adopts that standard,10 and in addition has a dose standard of 100 mrem
per year for members of the public from operations licensed by NRC.11 That agency also has
established an occupational dose limit of 5 rem per year.12 The occupational dose limit in Japan
was reportedly 10 rem per year, a figure raised to 25 rem per year in the wake of the Fukushima
Daiichi incident.13 According to one expert, doses greater than 25 rem are often received in a
short period of time, producing deterministic effects, the severity of which increases with dose.14
As the foregoing discussion shows, there is no single level that marks the line between an
acceptable and unacceptable dose.
An RDD attack would elevate dose in the affected area beyond background. The Environmental
Protection Agency (EPA) issued guidance in 1991 for protective actions following nuclear and
radiological incidents except nuclear war, and the Federal Emergency Management Agency
(FEMA) issued guidance in 2008 for protection and recovery following RDD and improvised
nuclear device (IND, i.e., a terrorist-made nuclear weapon) incidents.15 16 Both agencies
6

The International System of Units, used widely outside the United States, uses a different unit, the sievert (Sv), where
1 Sv = 100 rem, and 1 millisievert (mSv) = 0.1 rem.
7
National Council on Radiation Protection and Measurement, Ionizing Radiation Exposure of the Population of the
United States, report 160 (2009), available through http://www.ncrppublications.org/Reports/160. The figure of 620
mrem (6.2 millisievert) is from the council’s webpage “NCRP Report No. 160 Section 1 Pie Chart,”
http://www.ncrponline.org/Publications/160_Pie_charts-Sec1.html, and the pie chart showing the contribution of
various sources of radiation to dose is at http://www.ncrponline.org/images/160_pie_charts/Fig1-1.pdf.
8
U.S. Nuclear Regulatory Commission. “Fact Sheet on Biological Effects of Radiation,” http://www.nrc.gov/readingrm/doc-collections/fact-sheets/bio-effects-radiation.html.
9
10 CFR 190.10(a).
10
20 CFR 1301(e).
11
20 CFR 1301(a)(1).
12
20 CFR 1201(a)(1)(i).
13
Keith Bradsher and Hiroko Tabuchi, “Last Defense at Troubled Reactors: 50 Japanese Workers,” New York Times,
March 16, 2011, p. 1.
14
Dade Moeller, Environmental Health, revised edition (Cambridge, Harvard University Press, 1997), p. 250.
15
U.S. Environmental Protection Agency. Office of Radiation Programs. Manual of Protective Action Guides and
Protective Actions for Nuclear Incidents, revised 1991 (second printing, May 1992), http://www.epa.gov/radiation/
docs/er/400-r-92-001.pdf; and Federal Emergency Management Agency, "Planning Guidance for Protection and
(continued...)

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recommended “protective action guides” (PAGs). A PAG is “the projected dose to a reference
individual, from an accidental or deliberate release of radioactive material, at which a specific
protective action to reduce or avoid that dose is recommended. Thus, protective actions are
designed to be taken before the anticipated dose is realized.”17 PAGs provide guidance on
emergency actions like sheltering in place or evacuation.
FEMA divides the incident response into three phases. The early phase starts “at the beginning of
the incident when immediate decisions for effective protective actions are required, and when
actual field measurement data generally are not available.” The beginning is not necessarily clear.
While an explosive-driven dirty bomb would announce its presence, FEMA observes that “in the
event of a covert dispersal, discovery or detection may not occur for days or weeks.”18 For the
early phase, for a PAG of 1 to 5 rem, the protective action recommendation is sheltering in place
or evacuation.19 The intermediate phase after an attack “is usually assumed to begin after the
incident source and releases have been brought under control and protective action decisions can
be made based on measurements of exposure and radioactive materials that have been
deposited.”20 For that phase, FEMA recommends “relocation of the public” for a projected dose
of 2 rem for the first year and 0.5 rem per year for any subsequent year.21 22 PAGs assume that a
person is in the affected area, unprotected, 24 hours a day, 7 days a week, for the entire period.
This is unrealistic; sheltering and cleanup would reduce dose below the assumed level in the
event of an RDD attack. The late phase starts when recovery and cleanup begin, and ends when
such actions have been completed. FEMA does not have a PAG for the late phase because it
would not be an emergency situation and because authorities would need to optimize among
many factors (economic, land use, technical feasibility, etc.) in determining which areas need to
be remediated to what levels.
As a guide to quantities of material that should be protected, in 2003 the International Atomic
Energy Agency (IAEA) revised its Code of Conduct on the Safety and Security of Radioactive
Sources.23 The IAEA decided that the code “should serve as guidance to States for—inter alia—
the development and harmonization of policies, laws and regulations on the safety and security of
radioactive sources.”24 It lists 16 radionuclides that are in common use and could pose a threat.
For each radionuclide, the code lists three categories of radiation and the threshold radiation value
for each category based on potential to cause deterministic effects. Category 1 sources are those
(...continued)
Recovery Following Radiological Dispersal Device (RDD) and Improvised Nuclear Device (IND) Incidents," 73
Federal Register 45029-45048, August 1, 2008.
16
The U.S. Centers for Disease Control and Prevention offers a guide to personal protection in the event of an RDD
attack, “Frequently Asked Questions (FAQs) About Dirty Bombs,” http://emergency.cdc.gov/radiation/dirtybombs.asp.
17
Federal Emergency Management Agency, "Planning Guidance for Protection and Recovery Following Radiological
Dispersal Device (RDD) and Improvised Nuclear Device (IND) Incidents," 73 Federal Register, August 1, 2008, p.
45034.
18
Ibid., p. 45032.
19
Ibid., pp. 45032, 45035.
20
Ibid., p. 45032.
21
Ibid., p. 45035.
22
The levels selected for PAGs were controversial. Some felt that PAG dose levels could be applied to situations other
than a nuclear or RDD attack, supplanting standards that set dose at lower levels, which “could lead to dramatically
weakened public protections.” Douglas Guarino, “Obama Team to Review Contentious Bush EPA Nuclear Emergency
Guide,” InsideEPA.com, January 26, 2009.
23
International Atomic Energy Agency, Code of Conduct on the Safety and Security of Radioactive Sources, January
2004, http://www.iaea.org/Publications/Booklets/RadioactiveSources/radioactivesource.pdf.
24
International Atomic Energy Agency, Code of Conduct on the Safety and Security of Radioactive Sources, p. 2.

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that, if not safely managed or securely protected, could cause permanent injury to someone who
handled them for a few minutes, and death to someone who handled them unshielded for a few
minutes to an hour. For Category 2 sources, the corresponding figures are minutes to hours and
hours to days. Category 3 sources, if not safely managed or securely protected, could cause injury
to someone handling them for some hours.25
NRC found, “Of the 16 radionuclides, only four are widely used in civilian applications in this
country: Cobalt-60, cesium-137, iridium-192, and americium-241.”26 An expert panel highlighted
the risk from cesium-137 chloride:
Because of its dispersibility, solubility, penetrating radiation, source activity, and presence
across the United States in facilities such as hospitals, blood banks, and universities, many of
which are located in large population centers, radioactive cesium chloride is a greater
concern than other Category 1 and 2 sources for some attack scenarios. This concern is
exacerbated by the lack of an avenue for permanent disposal of high-activity cesium
radiation sources, which can result in disused cesium sources sitting in licensees’ storage
facilities. As such, these sources pose unique risks.27

The Energy Policy Act of 2005 (P.L. 109-58, Section 651 (d)) mandates certain security measures
for Category 1 and 2 sources as defined by the IAEA Code of Conduct. While the thresholds for
the various categories in the code are based on the potential to cause deterministic effects, NRC
considers Category 2 sources to be risk-significant: “The theft or diversion of risk-significant
quantities of radioactive materials could lead to their use in a radiological dispersal device (RDD)
or a radiological exposure device (RED).”28 Since NRC judges that Category 2 sources could
cause significant economic effects, the agency uses the lower threshold for Category 2 as the
basis for mandating security measures beyond those in the Energy Policy Act.
Category 2 quantities are very small, often a fraction of a gram. For example, the quantity of
concern for cesium-137 is 0.31 grams, which has 27 curies. Somewhat larger amounts can
contaminate a substantial area. For example, 50 grams (1.8 ounces) of cesium-137 chloride would
have about 1,000 curies. Figure 1 models an RDD attack on Washington, DC, using 1,000 curies
of this substance, which contaminates, to different levels, zones ranging in area from 0.81 to 5.10
square miles.

25

Ibid., p. 15.
“Prepared Statement of Robert J. Lewis,” Director, Division of Materials Safety and State Agreements, Nuclear
Regulatory Commission, in U.S. Congress. House. Committee on Homeland Security. Subcommittee on Emerging
Threats, Cybersecurity, and Science and Technology, Status Report on Federal and Local Efforts to Secure
Radiological Sources, field hearing, Brooklyn, NY, 111th Congress, 1st Session, serial no. 111-34, September 14,
2009, p. 21. The number following the name of the element represents the number of protons plus neutrons in the
atom’s nucleus.
27
National Research Council. Radiation Source Use and Replacement, Abbreviated Version, p. 7.
28
Nuclear Regulatory Commission, “Physical Protection of Byproduct Material: Proposed Rule,” 75 Federal Register
33902, June 15, 2010. An RED would place radioactive material so as to expose people to radiation, rather than
dispersing such material; see “RDDs and Nuclear Weapons.”
26

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Figure 1. A Possible RDD Attack on Washington, DC
Using 1,000 Curies of Cesium-137 Chloride

Source: William Rhodes III, Senior Manager, International Security Systems Group, Sandia National
Laboratories, September 2010; analysis by Heather Pennington; graphics by Mona Aragon.
Notes: (provided by William Rhodes): This map, based on an atmospheric dispersion model, shows where
individuals are projected to have an increased risk of developing cancers due to radiation exposure over a year
or more. The RDD in this scenario uses 1,000 curies of cesium-137 chloride (about 50 grams). The model
assumes that all material used is dispersed, but that it is not dispersed evenly over the area. Wind is assumed to
be from west to east at 7 mph. The model includes exposure from radioactive material both deposited on the
surface and resuspended into the air and inhaled. EPA and FEMA have developed Protective Action Guides
(PAGs) to indicate when long-term relocation of individuals should be considered. PAGs are primarily based on
an assessment of the risk of developing cancer over an exposed individual’s lifetime. They assume, conservatively,
that individuals are unsheltered and remain in the area during the entire period described for each contour.
Contours show where individuals, if not relocated per the PAG, are projected to receive at least a specified dose
in a specified time, as follows: inner contour (red), dose in first year post-attack, >2.00 rem; middle contour
(orange), dose in second year post-attack, >0.500 rem; and outer contour (yellow), cumulative dose in the first
50 years post-attack. >5.00 rem. The cigar-shaped plumes often seen in models of atmospheric dispersion occur

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for gases or very fine particles, which would be the case for chemical warfare agents or fallout from a nuclear
weapon but not in the case depicted. Whether such plumes would occur for an RDD depends on such factors as
wind speed, type of explosive, and particle size.
(Provided by CRS): This note compares lifetime incidence of, and deaths from, cancer to those resulting from
the attack modeled in this Figure. For the United States, the lifetime risk of being diagnosed with cancer is 43.61
percent, and the lifetime risk of dying from cancer is 21.15 percent. (U.S. National Institutes of Health. National
Cancer Institute. Surveillance Epidemiology and End Results (SEER). “SEER Cancer Statistics Review 1975-2007,”
Tables 1.14 and 1.17, http://seer.cancer.gov/csr/1975_2007/results_merged/topic_lifetime_risk.pdf) For the
125,000 people in the affected area, the estimated lifetime incidence of cancer would thus be approximately
54,513 people, and the estimated lifetime deaths from cancer, 26,438. The attack would increase the lifetime
incidence of cancer by 461 people, and lifetime deaths from cancer by 314. The Figure assumes no relocation,
sheltering, or decontamination. All these actions would occur in the real world, significantly reducing cancer
incidence and deaths caused by the attack.

Might uranium or plutonium, the essential fuels of nuclear weapons, be used in an RDD?
Technical experts rarely if ever consider uranium as an RDD material because the amount of
radiation emitted per gram is extremely small, most of its gamma rays are of relatively low
energy, and it poses less of a biological hazard than plutonium. Plutonium could be used in an
RDD because of the biological hazards from alpha particles if inhaled. However, a terrorist group
seeking materials for an RDD would probably find it easier to obtain radionuclides with common
industrial uses; a terrorist group seeking to build a nuclear bomb would probably try to acquire
uranium highly enriched in isotope 235 (“highly enriched uranium”) rather than plutonium
because only the former can be used in the simplest type of nuclear bomb; and a terrorist group
seeking to build a nuclear bomb using plutonium would probably not squander any plutonium it
acquired on an RDD. On the other hand, spent nuclear fuel, a highly radioactive mixture of many
radionuclides including uranium and plutonium, could be used in an RDD.

RDDs and Nuclear Weapons
The type of RDD most commonly referenced in the press and in public discussion is the “dirty
bomb,” in which conventional explosives like dynamite disperse radioactive material, but a dirty
bomb is only one type of RDD. There are other ways to disperse such material, such as placing it
in traffic or dropping it from an airplane. Terrorists might also use a “radiological exposure
device” (RED), in which radioactive material is placed (but not dispersed) so as to expose people
to radiation. REDs would harm only people who remained near them for a length of time, and
would contaminate little or no area; accordingly, they are of less concern than RDDs and this
report makes only brief reference to them.
It is important to clear up a common misconception. The public and the media tend to lump
nuclear weapons and RDDs together, probably because both involve radioactive materials.29
However, the materials and processes used are very different, and so are the results. An RDD
simply disperses radioactive material. The danger comes from radiation. The main physical effect
of an effective RDD attack would be as an area denial weapon, contaminating perhaps several
square miles to the extent that the affected population would have to relocate and requiring costly
cleanup. An attack would likely have economic and psychological effects as well, but would
cause no destruction (except that resulting from the explosion of a dirty bomb) and would
29

This confusion may be beneficial. Uranium would have little physical effect if used in an RDD even though a certain
form of uranium is suitable for a nuclear weapon. Yet James Cummings reportedly had acquired uranium in an
apparent attempt to create an RDD. Walter Griffin, “Report: ‘Dirty Bomb’ Parts Found; Radioactive Materials
Recovered from Home of Belfast [ME] Man Allegedly Slain by His Wife,” Bangor Daily News, February 11, 2009.

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probably kill few if any people promptly. A nuclear weapon uses uranium and plutonium, which
are much less radioactive than the materials most effective in an RDD. The process is that fission
and fusion of uranium, plutonium, and other materials release a vast amount of energy. The
resulting explosion produces immediate blast and heat effects that can destroy a large part of a
city and kill tens of thousands of people, and generates radioactive fallout whose impact would be
felt over a longer term and a wider area. Estimates differ as to the area an RDD and a nuclear
weapon would contaminate with radioactive material, depending on the height of burst of a
nuclear weapon (and thus the quantity of material it lofted into the atmosphere that would become
fallout), dispersibility of RDD material, wind patterns, radiation level at which an area is
considered contaminated, and so on. A ground-burst nuclear weapon would contaminate a far
larger area than an RDD.
While an attack using a nuclear weapon, such as a terrorist-made improvised nuclear device
(IND), would be far more destructive, many see an RDD attack as more likely. It would be
difficult for terrorists to make an IND on their own. They would need “special nuclear material”
(SNM, mainly uranium highly enriched in isotope 235 or plutonium), which is heavily guarded,
as well as extensive design work, precision equipment, and people with specialized skills. In
contrast, radioactive materials that might be of use in an RDD are in use around the world, often
in unguarded facilities. If terrorists obtained such material, they could disperse it using
conventional explosives or other low-tech means. They could not manufacture the active
materials for an IND or RDD, so would have to acquire them through other means.

Value of RDDs for Terrorists
An RDD’s effects could meet multiple goals that terrorists might have. Effects include the
following, listed here in the sequence in which they might occur:
•

Prompt casualties, which would most likely come only from the explosion of a
dirty bomb; many experts believe they would be few in number.30

•

Panic. As an example of the panic potential of RDDs, a 2007 study by the
University of Chicago’s National Opinion Research Center found that 65 percent
of urban residents said they would evacuate in the event of an RDD attack if the
government made no recommendation on evacuation, and 39 percent said they
would do so even if the government advised against evacuation.31 Even an attack
that released little radiation might cause panic.

•

Economic disruption. If a port or city center were contaminated with radioactive
material, commerce there might be suspended.

30
Richard Meserve, former Chairman, Nuclear Regulatory Commission, held that an RDD might cause “deaths on the
order of tens of people in most scenarios.” U.S. Congress. Senate. Committee on Foreign Relations. Dirty Bombs and
Basement Nukes: The Terrorist Nuclear Threat, hearing, 107th Congress, 2nd Session, 2002, p. 8.
31
Michael Meit et al., Spontaneous Evacuation Following a Dirty Bomb or Pandemic Influenza: Highlights from a
National Survey of Urban Residents' Intended Behavior, National Opinion Research Center, Walsh Center for Rural
Health Analysis, Policy Analysis Brief, W Series, No. 12, Chicago, IL, and Bethesda, MD, November 2007, pp. 1-2,
http://www.norc.org/nr/rdonlyres/7bebba5f-a019-4846-9885-3c7dc537e4ae/0/
spontaneousevacuationfollowingadirtybomborpandemicinfluenza.pdf.

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•

Asset denial. Public concern over the presence of radioactive material might lead
people to abandon a building, subway system, or an area of a city for months to
years.

•

Decontamination, which might be done with chemicals or through demolition
and reconstruction at a cost of billions of dollars.

•

Long-term casualties resulting from exposure to or inhalation of radioactive
material.

More speculatively, terrorists might see an RDD attack as an advertisement and a recruiting tool.
A 2007 study casts light on how an RDD attack might inflict economic damage and asset denial.
The study analyzed RDD attacks on the ports of Los Angeles and Long Beach:
Initial findings suggest that the chances of a successful dirty bomb attack are about 10–40%
and that high radiological doses are confined to a relatively small area, limiting health effects
to tens or at most hundreds of latent cancers, even with a major release. However, the
economic consequences from a shutdown of the harbors due to the contamination could
result in significant losses in the tens of billions of dollars, including the decontamination
costs and the indirect economic impacts due to the port shutdown.32

Another study of the economic impacts of an attack on these ports using two RDDs assumed that
the ports were shut for a month with no mitigation and no use of alternative ports. It placed the
total U.S. losses at $8.5 billion for exports and $26.0 billion for imports.33 An NNSA-sponsored
study of the economic impacts of RDDs “modeled the impacts of four specific radioactive
sources … Even without weaponization of the radioactive materials or optimization of the device
the study found that the economic cost to the Nation could be in the billions of dollars. Costs
included evacuation, relocation, clean-up, and lost wages.”34

The Threat: Feasibility, Fear, Probability, Impediments
James Clapper, Director of National Intelligence, said in March 2011, “Some terror groups
remain interested in acquiring CBRN materials and threaten to use them.”35 Terrorists could
readily detonate explosives placed next to radioactive material, and there is much fear about the
consequences of an attack. Yet the probability of an RDD attack is unknown (see “Difficult
Metrics”), terrorists would face impediments to launching a successful attack, and there has been
no successful RDD attack as of May 2011. While the public tends to infer threat and probability
from feasibility and fears, the reality is more complex.
32

H. Rosoff and D. von Winterfeldt, "A Risk and Economic Analysis of Dirty Bomb Attacks on the Ports of Los
Angeles and Long Beach," Risk Analysis, vol. 27, no. 3 (2007), pp. 533-546.
33
JiYoung Park, “The Economic Impacts of Dirty Bomb Attacks on the Los Angeles and Long Beach Ports: Applying
the Supply-Driven NIEMO (National Interstate Economic Model,” Journal of Homeland Security and Emergency
Management, vol. 5, no. 1 (2008), article 21, p. 10, http://www.bepress.com/jhsem/vol5/iss1/21/.
34
Prepared statement of Kenneth Sheely, Associate Assistant Deputy Administrator for Global Threat Reduction,
National Nuclear Security Administration, in House Homeland Security Committee, Status Report on Federal and
Local Efforts to Secure Radiological Sources, p. 13. The study referenced is Los Alamos National Laboratory,
Economic Impacts of Detonating Radiological Dispersion Devices, February 15, 2008, LA-CP-08-00973.
35
James Clapper, Director of National Intelligence, “Statement for the Record on the Worldwide Threat Assessment of
the U.S. Intelligence Community for the Senate Committee on Armed Services,” March 10, 2011, p. 3, http://armedservices.senate.gov/statemnt/2011/03%20March/Clapper%2003-10-11.pdf.

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It appears feasible for terrorists to acquire the radioactive material needed to build an RDD. Such
material is in “widespread use in nearly every country,”36 and there are questions about the
vulnerability of facilities housing sealed sources to a carefully planned terrorist attack. Security of
sources is discussed in detail in “Preventing an Attack.”
Another aspect of the threat is that theft of one device could result in several RDDs. According to
NNSA, “Some devices have more than one radioactive source, and a single source can be
subdivided into smaller pieces to create more than one radiological dispersal device (RDD) or
radiation exposure device (RED). If a theft were to occur responders should be prepared for the
potential of multiple RDD/RED events.”37
While the Nuclear Security Summit of April 2010 focused on protecting the world against
terrorist use of nuclear weapons, some leaders expressed concern about RDDs. Pakistani Prime
Minister Syed Yusuf Raza Gilani said, “We need strong national actions and greater international
coordination to prevent illicit trafficking in nuclear materials. The threat of terrorist acts involving
‘dirty bombs’ is more real and it has global dimensions. We should take additional measures to
combat this threat.”38 A news report stated, “Ahead of the [Nuclear Security Summit] conference,
German Chancellor Angela Merkel made it clear that she, too, sees dirty bombs in terrorist hands
as an even larger threat than regular nuclear weapons. Merkel said Monday that such weapons
‘must not under any circumstances’ fall into the hands of terror groups such as al Qaeda. ‘We
believe that the IAEA must be strengthened, we are ready to pledge additional finances to make
this happen.’”39 At a conference, “Global Efforts in WMD Threat Reduction,” held at the
Canadian Embassy in Washington on March 11, 2011, speakers representing several governments
indicated that security of radiological sources would play a much more prominent role at the 2012
Nuclear Security Summit in Seoul than was the case at the 2010 summit. Cho Hyun, the sherpa
for the Republic of Korea, suggested including the security of radioactive materials in the agenda
of the 2012 summit.40 (A “sherpa” is the individual in charge of a nation’s preparations for a
summit meeting.)
U.S. officials have expressed concern about RDDs but do not imply an immediate threat. Dennis
Blair, then Director of National Intelligence, stated, “We judge that, if al-Qa’ida develops
chemical, biological, radiological, or nuclear (CBRN) capabilities and has operatives trained to
use them, it will do so. Counterterrorism actions have dealt a significant blow to al-Qa’ida’s nearterm efforts to develop a sophisticated CBRN attack capability, although we judge the group is
still intent on its acquisition.”41 Robert Mueller III, Director of the Federal Bureau of
36

U.S. Department of State. Office of the Coordinator for Counterterrorism. Country Reports on Terrorism 2009,
August 2010, p. 200, http://www.state.gov/documents/organization/141114.pdf.
37
U.S. Department of Energy. National Nuclear Security Administration. Global Threat Reduction Initiative. “GTRI
Table Top Exercise Series Lessons Learned,” March 2010, p. 3.
38
Pakistan. Press Information Department. “Opening Remarks: Threat of Nuclear Terrorism,” Prime Minister’s
Intervention at the Dinner Session on 12 April 2010, http://www.pid.gov.pk/
pm_Opening%20Dinner%20Remarks%20Final13410.doc.
39
CBS News, “Obama Opens Summit with Optimism,” April 12, 2010 (Monday), http://www.cbsnews.com/stories/
2010/04/12/world/main6386991.shtml.
40
Cho Hyun, Deputy Minister for Multilateral and Global Affairs, Ministry of Foreign Affairs and Trade, Republic of
Korea, “Preparation for Nuclear Security Summit 2012 and Possible Deliverables,” presentation at the Ninth ROK-UN
Conference on Disarmament and Nonproliferation Issues, Jeju, Republic of Korea, December 3, 2010, available via
http://jejuprocess.tistory.com/entry/Session-3-Enhancing-Nuclear-Security-and-Preventing-Nuclear-Terrorism.
41
Dennis C. Blair, Director of National Intelligence, “Annual Threat Assessment of the US Intelligence Community for
the Senate Select Committee on Intelligence,” February 2, 2010, p. 9, http://www.dni.gov/testimonies/
20100202_testimony.pdf.

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Investigation, testified, “Al Qaeda remains committed to its goal of conducting attacks inside the
United States … al Qaeda’s continued efforts to access chemical, biological, radiological, or
nuclear material pose a serious threat to the United States.”42 According to a State Department
report, “Some terrorists seek to acquire radioactive materials for use in a radiological dispersal
device.”43
Over the years, there have been thefts of radioactive material and attempts to use it for malevolent
ends, and a few have been successful, as the following examples show:44
•

(1993) “The Russian mafia allegedly places gamma ray-emitting pellets in the office of a
Moscow businessman, resulting in the man’s death.”

•

(1995) “Chechen rebels partially bury a container with a small quantity of cesium-137 in
Moscow’s Ismailovsky Park. The Chechen leader then notifies a Russian television crew,
which locates the container.”

•

(1998) “19 small tubes of cesium are reported missing from a locked safe in a
Greensboro, North Carolina hospital. … The incident is deemed as a theft … The cesium
has not been recovered.”

•

(1998) “the Russian-backed Chechen Security Service announces the discovery and
defusing of a container hidden near a railway line that was filled with radioactive
materials and attached to an explosive mine. Chechen rebels involvement is suspected.”

•

(1999) “unidentified thieves attempt to steal a container housing 200g of radioactive
material from a chemical factory in Grozny, Chechnya. One of the thieves dies half an
hour after being exposed to the container. The other is hospitalized in critical condition.
Each carried the container for only a few minutes.”

•

(2003) “evidence uncovered in Herat, Afghanistan, leads British intelligence agents and
weapons experts to conclude that Al Qaeda has succeeded in constructing a small dirty
bomb, though the device has not been found.”

•

(2003) “Thai police arrest a public school teacher in Bangkok after he attempts to sell a
container filled with cesium-137 for $240,000.”

•

(2004) “British authorities arrest an alleged terrorist cell that was apparently plotting to
create dirty bombs from the radioactive sources inside smoke detectors. (It would require
millions of smoke detectors to collect enough radioactive material for a potent RDD.)”

•

(2005) “Russian authorities report that they found documents in Chechnya on producing
RDDs.”

42

Robert S. Mueller, III, Director, Federal Bureau of Investigation, “Statement Before the House Committee on
Appropriations, Subcommittee on Commerce, Justice, Science, and Related Agencies,” March 17, 2010, pp. 2-3,
http://appropriations.house.gov/Witness_testimony/CJS/Robert_Mueller.3.17.10.pdf.
43
U.S. Department of State. Office of the Coordinator for Counterterrorism. Country Reports on Terrorism 2009,
August 2010, p. 200, http://www.state.gov/documents/organization/141114.pdf.
44
These examples are from Nuclear Threat Initiative, Radiological Terrorism Tutorial, “History of Radiological
Incidents,” http://www.nti.org/h_learnmore/radtutorial/chapter03_01.html.

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•

(2006) “Alexander Litvinenko, a former Russian spy, was poisoned with radioactive
polonium-210.”

But fears and feasibility do not equate to threat, and murders, thefts, documents, a made-for-TV
demonstration, “sting” operations, and foiled or poorly planned terrorist plots do not rise to the
level of a successful RDD attack. The threat is plausible, but as with any high-consequence/lowfrequency event, the sample size (at least using publicly-available information) is not large
enough to support predictions of the likelihood of such an attack.
It would be much harder for terrorists to launch an effective RDD attack, 45 as distinct from
making a crude RDD, for reasons such as the following. While no one of them presents an
insurmountable obstacle, the combination may help explain why an attack of this sort has not
occurred, and indeed could help deter attack by reducing the probability of success.
•

Terrorists would need to know something about radiation. Various forms of
radiation cause damage in differing ways. Alpha and beta emitters are most
damaging inside the body, while gamma and neutron emitters are damaging
inside or outside the body. Different radionuclides emit different amounts of
energy when they decay, as Figure 1 shows. Higher-energy radiation causes
more biological damage. Even terrorists who were willing to die in an attack
would need to know something about radiation safety for self-protection, as they
could die if they did not handle the material properly, or if they did not know the
curie content of material they had obtained.

•

Terrorists would need to know something about radioactive materials. Obtaining
the wrong material could render an RDD useless. Materials with very short halflives (e.g., a week or less) would have to be used quickly and would produce
negligible long-term contamination. Materials with very long half-lives (over
100,000 years) would be undesirable for an RDD because only an enormous
mass, possibly tons, could generate enough radiation to pose a threat. Different
radionuclides emit different amounts of energy when they decay, as Figure 1
shows, and higher-energy radiation causes more biological damage. Chemical
characteristics are also important. Some compounds dissolve in water more
readily than others. Some elements (including their radioactive isotopes) and
some chemical compounds bond more strongly to concrete and tile than others,
making cleanup difficult.46 47

•

Terrorists would have to conceal their actions, locations, and identities from law
enforcement and intelligence services of many nations.

•

Terrorists would have to obtain the material. NRC regulations enhance security
for high-risk sources in the United States. While lost and abandoned sources
exist, it would be hard to locate them in the United States or elsewhere. An attack

45

In this report, “Value of RDDs for Terrorists” discusses potential effects of an attack, and “Impact of an Attack”
discusses difficulties of finding a suitable metric for attack effectiveness.
46
J. Real, F. Persin, and C. Camarasa-Claret, “Mechanisms of Desorption of 134Cs [cesium-134] and 85Sr [strontium85] Aerosols Deposited on Urban Surfaces,” Journal of Environmental Radioactivity, vol. 62, no. 1 (2002), pp. 1-15,
http://www.ncbi.nlm.nih.gov/pubmed/12141602.
47
Cesium is a constituent element of several chemical compounds (e.g., cesium chloride), as is strontium. Some of
these compounds bond strongly to concrete, while others do not. Information provided by William Rhodes, Sandia
National Laboratory, personal communication, December 17, 2010.

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that aimed to seize radioactive materials might (or might not) meet armed
resistance. It may be possible to obtain radioactive sources by using bogus means
to obtain licenses, as GAO did,48 but NRC has tightened guidelines for licensing
to counter that risk. Other nations have different, and in some cases lower,
standards for protecting radioactive material than does the United States, so it
may be easier to obtain sources abroad, but they would have to be smuggled in,
risking detection at multiple points along the way.
•

Terrorists might want to extract the material from its capsule or other container,
exposing them to radiation, possibly in lethal doses. This is particularly the case
for Category 1 and 2 sources. If terrorists sought to create a bomb by placing an
unopened sealed source next to explosives, it would be less effective.

•

Terrorists would have to ensure the device dispersed material over the desired
area. An RDD that dispersed material too widely might contaminate a large area
to a very low level, while one that dispersed material over a very limited area,
less than a city block, would place only that area off-limits, permitting workers to
concentrate remediation efforts there. A wind shift could blow the material away
from the target. A considerable amount of material might not disperse at all.

•

Terrorists would have to move the material past detectors at U.S. ports of entry
and at various places within the United States.

•

Terrorists would have to acquire the other materials and equipment for a bomb,
assemble the bomb, and place it. Law enforcement work might detect such steps.

•

Emergency response, such as public alerts, evacuation or shelter-in-place
instructions, and medical care, could reduce casualties and panic.

•

Forensic analysis might reveal the perpetrator of the attack and the country from
which the radioactive and other materials originated; the possibility of retaliation
might make countries think twice before helping terrorists conduct an attack.

•

Terrorists might judge that an RDD attack would lead swiftly to attacks on
terrorist groups and to worldwide implementation of more stringent measures to
counter all types of terrorist threats, closing future opportunities, so they might
see the “costs” of an RDD attack as outweighing the “benefits.”

Area Contaminated by an RDD Attack and Cost to Decontaminate
Press articles sometimes point to scenarios showing that an RDD could contaminate a large area
and that cleanup would be costly. The reality is more complex: area and cost depend on the
maximum acceptable dose and other assumptions chosen for a scenario. Figure 2 and Figure 3,
from a study by Defence Research and Development Canada and Battelle,49 illustrate the point.
Figure 2 shows plumes from an RDD under the following assumptions. The RDD contains 1,000
curies of cesium-137; it is explosive-driven and detonated at BC Place Stadium in Vancouver,
48
U.S. Government Accountability Office. Nuclear Security: Actions Taken by NRC to Strengthen Its Licensing
Process for Sealed Radioactive Sources Are Not Effective, GAO-07-1038T, July 12, 2007, http://www.gao.gov/
new.items/d071038t.pdf.
49
Tom Cousins and Barbara Reichmuth, Preliminary Analysis of the Economic Impact of Selected RDD Events in
Canada, Defence Research and Development Canada and Battelle, PNWD-SA-7845, c. 2007.

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BC; wind speed is 3 meters per second (6.7 mph); and other weather conditions (temperature,
rain, humidity, wind speed and direction at different altitudes, etc.) are not considered. Plumes
show contamination at four dose levels: 15, 30, 100, and 500 millirem (mrem) per year.50 As
Figure 3 shows, area deemed contaminated and costs inflicted by the attack depend on dose. The
outermost plume, with a dose of 15 mrem per year, covers 99 square miles (256 square km) and
associated costs of $80 billion, while the innermost plume, with a dose of 500 mrem per year
covers 2.3 square miles (6 square km), with associated costs of $10 billion.
Figure 2. Area Contaminated by an RDD Attack
Using 1,000 Curies of Cesium-137

Source: Tom Cousins and Barbara Reichmuth, Preliminary Analysis of the Economic Impact of Selected RDD Events
in Canada, Defence Research and Development Canada and Battelle, PNWD-SA-7845, c. 2007.

50

Dose in the affected area would diminish continuously over time because of radioactive decay and weather effects
(e.g., rain moving particles of material into the ground, providing some shielding). As a result, radioactive material that
produced a given dose in the first year postattack would produce a progressively lower dose in each subsequent year.
Cost figures are in Canadian dollars.

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Figure 3. Area Contaminated to Various Levels, and Resulting Costs
For an Attack Using 1,000 Curies of Cesium-137

Source: Tom Cousins and Barbara Reichmuth, Preliminary Analysis of the Economic Impact of Selected RDD Events
in Canada, Defence Research and Development Canada and Battelle, PNWD-SA-7845, c. 2007.

Preventing an Attack
The United States and other nations use a “layered defense” strategy in seeking to prevent an
RDD attack. No layer is expected to be perfect, but each increases the likelihood of disrupting a
terrorist attack. International, federal, state, and local organizations have added measures since
9/11 to prevent an RDD attack, and existing measures have been strengthened. (As discussed
under “Attack Response, Recovery, and Attribution,” programs to respond to an attack have also
increased.)

Domestic Efforts
Before September 11, 2001, the main concern for radioactive sources was their safe handling.
They were used worldwide in many applications with varying levels of security. While the United
States undertook some security measures prior to the attacks, the ongoing U.S. response to the
attacks includes new or augmented approaches to reducing the threat that radioactive sources may
pose. One is to protect sources through licensing, tracking, and physical security upgrades.
Another is to remove sources that are outside the tracking system because they are abandoned or
lost (“orphan sources”) or because they have been stolen for illegitimate uses, whether for an
RDD or for scrap metal. A third is to reduce the number of sources in use. Different programs
apply to one or more of these categories.

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Securing Radioactive Sources
Since materials of greatest concern for use in an RDD are made in nuclear reactors, terrorists
could only obtain them through transfer from sympathetic insiders, theft, or purchase. Securing
radioactive sources therefore reduces the risk of an RDD attack. Many government agencies and
other entities have taken steps to secure these sources; a few key examples follow.

Nuclear Regulatory Commission
NRC is an independent agency. It “has the responsibility to license and regulate the civilian use of
radioactive materials for commercial, industrial, academic, and medical purposes in a manner that
protects public health and safety and promotes the common defense and security. NRC and its
predecessor, the Atomic Energy Commission (AEC), have regulated the use of radioactive
materials since 1946.”51
The Atomic Energy Act of 1954, P.L. 83-703, amended the Atomic Energy Act of 1946. The 1954
act, as amended, “is the fundamental U.S. law on both the civilian and the military uses of nuclear
materials.”52 Section 161 gave the AEC the authority to regulate radioactive material “to promote
the common defense and security or to protect health or to minimize danger to life or property.”
Section 11 of the act defined “special nuclear material” as uranium enriched in the isotopes 233
or 235, plutonium, and other material as specified by the AEC, and defined “byproduct material”
as “any radioactive material (except special nuclear material) yielded in or made radioactive by
exposure to the radiation incident to the process of producing or utilizing special nuclear
material,” and tailings or wastes from uranium or thorium ore. Byproduct material cannot be used
as the active material in a nuclear weapon, but some types of it could be used in an RDD. Section
274 authorized NRC to enter into agreements with states (so-called “Agreement States”), giving
them the authority to license and regulate byproduct and certain other radioactive material for
public health and safety; NRC retained the authority to issue regulations for the common defense
and security. As of March 31, 2011, 37 states had entered into such agreements, and NRC was
evaluating additional states for participation in the program.53
Two other acts are particularly relevant to RDDs. The Energy Reorganization Act of 1974, P.L.
93-438, abolished the AEC and created the NRC. Section 201 transferred “all the licensing and
related regulatory functions” of the AEC to NRC.54 Section 651 of the Energy Policy Act of 2005,
P.L. 109-58, defined “radiation source” as Category 1 or Category 2 sources as per the IAEA
Code of Conduct and other material as determined by NRC, required NRC to issue regulations
governing exports and imports of radiation sources, required NRC to establish a mandatory
tracking system for radiation sources in the United States, and established a Task Force on
51
U.S. Nuclear Regulatory Commission. “Request for Comments on the Draft Policy Statement on the Protection of
Cesium-137 Chloride Sources and Notice of Public Meeting,” NRC-2010-0209, Federal Register, vol. 75, no. 124,
June 29, 2010, p. 37484.
52
U.S. Nuclear Regulatory Commission. “Our Governing Legislation,” http://www.nrc.gov/about-nrc/governinglaws.html.
53
U.S. Nuclear Regulatory Commission. “Agreement State Program,” http://www.nrc.gov/about-nrc/state-tribal/
agreement-states.html.
54
The Atomic Energy Act, as amended, and the Energy Reorganization Act, as amended, are available in U.S. Nuclear
Regulatory Commission. Office of the General Counsel. Nuclear Regulatory Legislation, 107th Congress, 1st Session,
NUREG-0980, vol. 1, no. 6, 2002, http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr0980/ml022200075vol1.pdf#pagemode=bookmarks&page=14.

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Radiation Source Protection and Security.55 Section 652 required licensees to fingerprint any
individual permitted unescorted access to certain radioactive material.
NRC has used these authorities to issue orders and regulations to enhance radiation source
security since the 9/11 attacks. For example, it issued an order in 2005 to improve the security of
irradiators having more than 10,000 curies,56 a rule in 2005 on security policy for import and
export of radioactive materials,57 and an order in 2006 regarding fingerprinting and criminal
history.58 Also in 2005, it issued an “Order Imposing Increased Controls (Effective Immediately)”
to licensees authorized to possess 16 types of radioactive material above certain “quantities of
concern.”59 These quantities are the same as Category 2 sources in the IAEA Code of Conduct.
The order required licensees to “allow only trustworthy and reliable individuals, approved in
writing by the licensee, to have unescorted access to radioactive material quantities of concern
and devices” and to “have a documented program to monitor and immediately detect, assess, and
respond to unauthorized access,” imposed requirements for transportation of radioactive
materials, and required physical controls for mobile or portable devices containing radioactive
material in quantities of concern.60 The NRC website has a full listing of its security orders.61 In
the Federal Register of June 15, 2010, NRC published for comments a proposed rule, “Physical
Protection of Byproduct Material,” that would incorporate and modify some previous orders as 10
CFR 37.62 The proposed rule would deal with “the security requirements for use of category 1 and
category 2 quantities of radioactive material.”63
Almost all of NRC’s budget is for nuclear reactors—licensing, safety, fuel, and spent fuel
management.64 However, NRC has many programs for security of radioactive sources. It issues
orders and regulations for licensees; inspects licensees to ensure compliance; and takes
enforcement action as needed. In January 2009, it instituted the web-based National Source
Tracking System to track Category 1 and 2 sources throughout their life cycle as required by the

55

The Energy Policy Act is available at http://www.epa.gov/oust/fedlaws/publ_109-058.pdf.
U.S. Nuclear Regulatory Commission, “In the Matter of All Panoramic and Underwater Irradiators Authorized to
Possess Greater than 370 Terabecquerels (10,000 Curies) of Byproduct Material in the Form of Sealed Sources; Order
Imposing Compensatory Measures (Effective Immediately),” Federal Reguster, vol. 68, no. 114, June 13, 2003, pp.
35458-35462. NRC redacted specific requirements except for those on handling information.
57
U.S. Nuclear Regulatory Commission, “Export and Import of Radioactive Materials: Security Policies,” final rule,
Federal Register, vol. 70, no. 126, July 1, 2005, pp. 37985-37994.
58
U.S. Nuclear Regulatory Commission. “In the Matter of Holders of Material Licenses Authorized to Manufacture or
Distribute Items Containing Radioactive Materials of Concern; Order Imposing fingerprinting and Criminal History
Records Check Requirements for Unescorted Access to Certain Radioactive Material and Modification of the
Additional Security Measures (Effective Immediately),” Federal Register 71, October 27, 2006, pp. 63046-63050.
59
U.S. Nuclear Regulatory Commission. “Order Imposing Increased Controls (Effective Immediately),” EA 05-090 in
the matter of licensees authorized to possess radioactive material quantities of concern, November 14, 2005,
http://adamswebsearch2.nrc.gov/idmws/doccontent.dll?library=PU_ADAMS^PBNTAD01&ID=053260115.
60
U.S. Nuclear Regulatory Commission. “Increased Controls for Licensees That Possess Sources Containing
Radioactive Material Quantities of Concern,” Attachment B to “Order Imposing Increased Controls (Effective
Immediately),” http://adamswebsearch2.nrc.gov/idmws/doccontent.dll?library=PU_ADAMS^PBNTAD01&ID=
053260013.
61
U.S. Nuclear Regulatory Commission. “Security Orders.” http://www.nrc.gov/reading-rm/doc-collections/
enforcement/security/index.html#6.
62
U.S. Nuclear Regulatory Commission. “Physical Protection of Byproduct Material; Proposed Rule,” Federal
Register, vol. 75, no. 114, June 15, 2010, pp. 33902-33947.
63
Ibid., p. 33904.
64
U.S. Nuclear Regulatory Commission. Congressional Budget Justification for FY 2011, NUREG-1100, volume 26,
February 2010, p. 3, http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1100/v26/sr1100v26.pdf.
56

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Energy Policy Act of 2005.65 As of March 2010, this system tracked over 70,000 sources, of
which 93 percent were cobalt-60, 3.5 percent were iridium-192, and 3 percent were cesium-137.66
In response to a GAO investigation that used bogus means to obtain a license to procure
radioactive material (see note 48), NRC changed licensing procedures to make them more secure.
It is responding, or has responded, to other GAO criticisms.67 It maintains a Nuclear Material
Events Database to track incidents and accidents that involve nuclear material.68 It operates the
Agreement States program discussed earlier.

National Nuclear Security Administration
NNSA is a semiautonomous agency within the Department of Energy. One of NNSA’s
components is Defense Nuclear Nonproliferation (DNN). DNN’s main program to enhance the
security of radioactive sources is the Global Threat Reduction Initiative (GTRI). Most of GTRI’s
budget is for international programs, but it operates domestic programs as well, and the two are
complementary in that they both help secure the United States and they draw on a common body
of knowledge. The FY2012 budget request for Defense Nuclear Nonproliferation is $2,549.5
million, and for GTRI, $508.3 million.69
GTRI’s Domestic Materials Protection Program provides security enhancements for domestic
radioactive sources on a voluntary basis. NNSA funds the security upgrades at a facility and their
initial maintenance, but the facility must agree to provide subsequent maintenance of the
upgrades.70 NRC and NNSA state that this program complements NRC’s security program for
these sources, with NRC setting the baseline for security and GTRI providing security upgrades
at GTRI’s expense for NRC licensees requesting assistance. Typically, a GTRI team visits a site
to assess how security might be improved and negotiates contracts to have equipment installed.
Equipment needs are site-specific; examples are iris scanners to control access, radiation
detectors and TV cameras to monitor intrusion, equipment to link alarms to local police, and
stronger doors and locks. NNSA has also developed In-Device Delay units that GTRI retrofits
into irradiators that use cesium chloride as the active material in order to give police more time to
respond to attempted thefts. Figure 4 and Figure 5 show security devices.

65
For information on this system, see U.S. Nuclear Regulatory Commission. “National Source Tracking System,”
http://www.nrc.gov/security/byproduct/nsts.html.
66
U.S. Nuclear Regulatory Commission. National Source Tracking System: Blog. “Fun Facts about NSTS!,” entry of
March 12, 2010, http://www.nrc.gov/security/byproduct/nsts/blog.html.
67
U.S. Nuclear Regulatory Commission. “Summary of NRC Actions [in] Response to GAO Reports,” March 19, 2010,
http://www.nrc.gov/reading-rm/doc-collections/congress-docs/correspondence/2010/carper-03-19-2010.pdf.
68
U.S . Nuclear Regulatory Commission. “Nuclear Material Events Database,” http://nmed.inl.gov/.
69
U.S. Department of Energy. Office of Chief Financial Officer. FY 2012 Congressional Budget Request, volume 1,
National Nuclear Security Administration. February 2011, DOE/CF-0057, p. 325, http://www.cfo.doe.gov/budget/
12budget/Content/Volume1.pdf.
70
U.S. Department of Energy. National Nuclear Security Administration. “NNSA: Securing Domestic Radioactive
Material,” fact sheet, February 1, 2011, p. 2, http://nnsa.energy.gov/print/mediaroom/factsheets/domestic.

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Figure 4. Iris Reader

Figure 5. Radiation Detector

Source: Photo by CRS

Source: Black Cat Systems

Notes: This biometric device is in use to control
access to a room with radioactive material. It was
installed through a contract with Global Threat
Reduction Initiative. The user looks into the two
brown ovals, and the device scans the irises to
determine if the person is authorized for access.

Notes: Radiation detectors alarm when radiation is
released. (This model is an example only, and is not
necessarily used to comply with NRC regulations.)

Many sources in the United States, mostly low-level, have been lost, abandoned, or stolen; are
excess to a user’s needs; or have become significantly less radioactive through decay. Another
part of GTRI’s work, therefore, is recovering radioactive sources. The Off-site Source Recovery
Project (OSRP), another GTRI program, performs this task. As of March 28, 2011, OSRP had
recovered 24,029 sources in the United States totaling 801,560 curies;71 while many were small
and many were well protected, some were “orphan” sources that were lost or abandoned. NNSA
expects to remove at least 2,200 excess sources within the United States each year.72
GTRI also operates a course, Alarm Response Training, at the Y-12 National Security Complex
for local law enforcement officers. As described by Kenneth Sheely, Associate Assistant Deputy
Administrator for GTRI, “Most on-site guards at facilities with radioactive sources are not armed
or large enough force strength to neutralize the threat. Therefore, the key responders are often offsite local law enforcement. Unfortunately, many local law enforcement officials are not made
aware of the nature of the material which is in use at hospitals, blood banks, universities, oil
fields, and manufacturing plants in their jurisdiction. It is important for their safety, and the safety
of their communities, that they receive proper training about radiological sources.”73 The course
involves classroom instruction on what radioactive materials might be encountered; the threat this
71
Los Alamos National Laboratory, “OSRP Sources Recovered,” as of March 28, 2011, http://osrp.lanl.gov/images/
Maps/Recoveries_to_Date.pdf.
72
U.S. Department of Energy. Office of Chief Financial Officer. FY 2011 Congressional Budget Request. volume 1,
National Nuclear Security Administration, DOE/CF-0047, February 2010, p. 439, http://www.cfo.doe.gov/budget/
11budget/Content/Volume%201.pdf.
73
“Prepared Statement of Kenneth Sheely,” Associate Assistant Deputy Administrator for Global Threat Reduction,
National Nuclear Security Administration, in U.S. Congress. House Homeland Security Committee, Status Report on
Federal and Local Efforts to Secure Radiological Sources, p. 17.

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material poses; how to use detection equipment; and operational exercise scenarios. GTRI, the
NNSA Office of the Under Secretary for Counterterrorism, and the FBI also provide table top
exercises to provide a site-specific scenario for organizations holding NRC licenses for
radioactive material and for managers at all levels of government to exercise their response to a
terrorist attack.74
GTRI programs within the United States operate on a small scale compared to their universe of
potential coverage. As of February 2011, GTRI had done the following.75 It had identified more
than 2,700 buildings in the United States with high-priority radiological materials, and had
completed security upgrades at 251 of them, “with the remainder aiming to be completed by
2025.” It had provided its Alarm Response Training course to 1,118 local law enforcement
officers. It had installed delay devices on 238 irradiators. GTRI’s pace has picked up since late
summer 2009. At that time, GTRI had completed security upgrades for 37 of about 2,200
buildings, provided its Alarm Response Training course to 175 personnel, and installed delay
devices on 32 irradiators.76 However, much work remains, some of which is presented in
Appendix B.

Relationship Between NRC and NNSA Programs
NRC and NNSA view their programs as complementary. According to a joint statement by the
two agencies, NRC and Agreement States (see “Nuclear Regulatory Commission”) have created
“a strong and effective regulatory framework that includes licensing, inspection, and
enforcement” that “provides a common baseline level of security to ensure adequate protection of
public health and safety and the common defense and security.” NNSA works with NRC and
others “to build on the existing regulatory requirements by providing voluntary security
enhancements.”77 A radiation safety officer who has partnered with GTRI expressed a similar
view. 78 (Radiation safety officers, as discussed later, are in charge of the safety and security of
radioactive materials at their facilities.)
NRC and GTRI have the same goal—no RDD attacks—but different roles. NRC has the
regulatory role. Licensees must follow its rules, which must be prescriptive enough to
improve security for all licensees that have quantities of concern; yet flexible enough to
cover large panoramic irradiators, research universities, and hospital blood banks. NRC must
enforce its rules impartially. When it interacts with a licensee, it cannot be too sensitive to
that licensee’s situation because anything they do for one could affect how they treat others.
In contrast, GTRI is not a regulator. It has a mandate to spend its funds to make partner sites
more secure. It is a voluntary program, and can be responsive to local site conditions. For
example, it may suggest security enhancements at a site, and the licensee may accept some,
reject some that wouldn’t work there, and modify others. If the outcome improves security,
GTRI will work with the site.
74

Ibid., p. 17.
U.S. Department of Energy. National Nuclear Security Administration. “NNSA: Securing Domestic Radioactive
Material,” fact sheet, February 1, 2011, p. 2.
76
“Prepared Statement of Kenneth Sheely,” pp. 16-17.
77
U.S. Nuclear Regulatory Commission and National Nuclear Security Administration., “Partnership for Securing
Nuclear and Radioactive Materials,” enclosure to U.S. Nuclear Regulatory Commission, “Development of a Joint
NRC-NNSA Key Messages Document, ‘Partnership for Securing Nuclear and Radioactive Materials,’ (FSME-10029),” March 31, 2010, http://www.nrc.gov/reading-rm/doc-collections/for-the-record/2010/protection-02-01-10.pdf.
Emphasis in original.
78
Personal communications, August and September 2010.
75

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This complementary relationship might lead some to ask whether the NRC and GTRI programs
should be combined to eliminate some overlap. The radiation safety officer just quoted, however,
argued against doing so:
These different roles set up tensions between GTRI and NRC. GTRI has a lot of freedom
because it is not the regulator, but it must work hard to keep the “blessing” of the NRC and
agreement states because licensees will not work with GTRI if NRC or agreement states tell
them not to. At the same time, GTRI wants to keep NRC out of their process. Having NRC
or agreement state staff accompany GTRI to the sites would change GTRI’s relationship
with licensees. I would not have partnered with GTRI if NRC was part of the process
because during GTRI’s security evaluation of our site, we had the freedom to identify
weaknesses. Licensees won’t show their problems to NRC for fear of being cited. As the
regulator, NRC cannot give assurances that violations uncovered during a voluntary site visit
will not be cited. So, I think GTRI shouldn’t be partnering with NRC.

Radiation Source Protection and Security Task Force
The Energy Policy Act of 2005 established the task force with a mandate to “evaluate, and
provide recommendations relating to, the security of radiation sources in the United States from
potential terrorist threats, including acts of sabotage, theft, or use of a radiation source in a
radiological dispersal device.” Its members represent 12 federal agencies and another four invited
agencies or organizations, with the NRC chairman or a designee as the chair.79 It is charged with
reporting every four years; it released its most recent report in August 2010.80 It “identified two
major challenges that require attention at higher levels.” First, access to disposal pathways for
unused sources, “already a challenge before 2006, has diminished substantially since that time,
and a comprehensive policy change is needed to overcome current barriers in the disposal
framework.”81 It recommended initiating or continuing efforts to develop, evaluate, and
investigate options for disposal of sources. Second, the task force examined alternatives to several
risk-significant radioactive sources. It pointed to three alternative technologies for existing
sources: using the same radionuclide but in a different form, replacing one radionuclide with
another, and using a technology (e.g., x-rays) in place of radioactive material. The report focused
on cesium-137 chloride, which “has long received increased attention from both a safety and
security perspective because of its potential dispersibility if removed from an irradiator or source
capsule.”82 The report recommended increased support to develop alternative technologies,
investigation of options to replace Category 1 and 2 sources, and review of whether licensing for
Category 1 and 2 cesium-137 chloride sources should be discontinued.83

79

Members of the task force are the Chairman of the NRC, Secretary of Homeland Security, Secretary of Defense,
Secretary of Energy, Secretary of Transportation, Attorney General, Secretary of State, Director of National
Intelligence, Director of the Central Intelligence Agency, Administrator of Federal Emergency Management Agency,
Director of Federal Bureau of Investigation, and Administrator of Environmental Protection Agency. Other invited
agencies are Department of Health and Human Services, Office of Science and Technology Policy, Organization of
Agreement States (non-voting member), and Conference of Radiation Control Program Directors (non-voting member).
80
U.S. Radiation Source Protection and Security Task Force. The 2010 Radiation Source Protection and Security Task
Force Report, August 2010, http://www.nrc.gov/security/byproduct/2010-task-force-report.pdf.
81
Ibid., p. 32.
82
U.S. Radiation Source Protection and Security Task Force. The 2010 Radiation Source Protection and Security Task
Force Report, p. 40.
83
Ibid., p. 45.

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Other Agencies
Other agencies have responsibilities for security as well. For example, the Environmental
Protection Agency (EPA) “is seeking to reduce the number of sealed radiation sources used in
industrial devices and applications. Through its Alternative Technologies Initiative, the Agency
has been working with industry since 2001 to identify non-nuclear substitutes.”84 This program
seeks to reduce the risk of industrial and environmental contamination and to protect sources
from seizure by terrorists. The Domestic Nuclear Detection Office is supporting R&D for the
same purpose through its Small Business Innovative Research program. The Department of
Defense (DOD) has some sealed sources in the United States, such as at hospitals. In such
instances, NRC grants DOD components, such as the Army, one or more licenses, and they
protect the sources in accordance with NRC regulations.85

How Secure Are Radioactive Sources in the United States?
An RDD attack is possible but its probability is unknowable. On the one hand, the NRC notes
common violations of security procedures, including “failure to escort all unauthorized
individuals” with access to Category 1 and 2 sources, “inoperable or ineffective physical
protection systems,” “incomplete or inadequate plan with local law enforcement,” “ineffective
barriers that can be easily defeated or bypassed,” and “failure to restrict access to only individuals
with a need to know and who have been determined trustworthy and reliable.”86 The NRC
reported that in FY2010, no Category 1 or 2 sources were lost; three Category 3 sources were lost
and recovered; and a Category 3 source fell into the Gulf of Mexico from an oil platform and was
not recovered.87 The FY2010 Radiation Source Protection and Security Task Force report stated,
“Every year, thousands of sources become disused and unwanted in the United States. While
secure storage is a temporary measure, the longer sources remain disused or unwanted the
chances increase that they will become unsecured or abandoned.”88 Most of these sources have a
very low level of radioactivity and do not pose a significant risk.89 Security of radioactive sources
has been upgraded since 9/11, but enhanced security measures, such as those of GTRI, have not
been completed. Appendix B discusses some of the tasks that GTRI has completed and those that
remain.
On the other hand, there have been “no successful thefts or sabotage” of Category 1 or 2
sources,90 and there has never been a successful RDD attack. The NRC’s Nuclear Material Events
Database shows that from the third quarter of FY2006 through the second quarter of FY2010, no
Category 1 sources were lost, and 17 Category 2 sources were lost but all were recovered.91 For
84

U.S. Environmental Protection Agency. “Alternative Technologies for Industrial Applications,” http://www.epa.gov/
radiation/source-reduction-management/alt-technologies.html.
85
Information provided by Chemical, Biological, Radiological, and Nuclear Directorate, Office of Homeland Defense
Integration and Defense Support of Civil Authorities, Office of the Secretary of Defense, Department of Defense,
personal communication, September 15, 2010, and by Nuclear Regulatory Commission, February 10, 2011.
86
U.S. Nuclear Regulatory Commission. “Security Inspections and Enforcement,” briefing slides 5-8, no date. NRC
provided these slides to CRS July 31, 2010.
87
U.S. Nuclear Regulatory Commission. Nuclear Material Events Database: Annual Report, Fiscal Year 2010,
http://nmed.inl.gov/AnnualReports/NMEDFY10%20Annual.pdf, p. ix.
88
U.S. Radiation Source Protection and Security Task Force. The 2010 Radiation Source Protection and Security Task
Force Report, p. 31.
89
Personal communication, Nuclear Regulatory Commission, November 30, 2010.
90
U.S. Nuclear Regulatory Commission. “Security Inspections and Enforcement,” slide 19.
91
Idaho National Laboratory, “Nuclear Material Events Database: Quarterly Report, Second Quarter Fiscal Year
(continued...)

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the period 1994 to 2005, the 2006 report of the Radiation Source Protection and Security Task
Force found
an average of about 5 lost or stolen risk-significant sources per year. In approximately 80
percent of the events for the 12-year period, the sources were recovered. This results in an
average of about one unrecovered source per year. Ninety-five percent of these lost and
stolen sources were Ir-192 [iridium-192] sources in radiography cameras that were
lost/stolen primarily because of the licensee’s failure to meet requirements. Because of the
short half-life of Ir-192 (74 days), these sources quickly decayed, and the current risk posed
by these sources is negligible.”92

It is unclear if this record is due to security measures, terrorist ineptness or disinterest, other
factors, or some combination.

Views from the Field
Many types of radioactive sources, including those in Categories 1 and 2, require NRC licenses.
The license is issued to a company, university, or other organization. The person responsible for
ensuring that the licensee maintains the safety and security of these sources is the radiation safety
officer (RSO). Since RSOs are the front line of radioactive source security in the United States,
they are in a position to provide “ground truth.” Accordingly, CRS conducted eleven interviews
with RSOs, ten by telephone and one in writing. Four RSOs were at industrial facilities, one was
at a hospital complex, and six were at universities. Seven had worked or were working with
GTRI; four had not done so. This section draws on these interviews, which also provide the basis
for some issues and options for Congress, discussed later. CRS has withheld names, locations,
and some other details to avoid compromising facility security.
RSOs are generally trained in safety, not security; many have advanced degrees in health physics
or similar fields. Prior to 9/11, security was a very small part of their work. They learned about
security through their work, often partnering with human resources (HR) personnel, local or
university law enforcement, lawyers, and security consultants. Based on CRS analysis, security
entails a different set of skills and a different culture. A central presumption of a safety culture is
that everyone is operating in good faith. No one wants to be a victim of a radiological accident,
and everyone recognizes that they must follow certain procedures to protect themselves and
others. A safety culture involves protecting people, e.g., through shielding and simple access
controls like door locks to prevent accidental exposure. In contrast, a central presumption of a
security culture is that terrorists, who may include insiders, may attempt to steal a radioactive
source in order to make an RDD and would look for security vulnerabilities. A security culture
therefore involves protecting radioactive sources through more robust means.
Before 9/11, RSOs focused on safety. Security sometimes consisted of a standard door lock on a
room with radioactive sources, mainly to prevent inadvertent exposure; security served safety. All
RSOs noted that security, and security awareness, at their facilities has improved since 9/11:
“Sometimes it seems that sources are so secure that I can’t get to them.” One said, “The sources
(...continued)
2010,” by Thomas Smith and Robert Sant, INL/EXT-10-18136 (FY 2010 Qtr 2), July 2010, p, 5. Annual reports of the
database are available at http://nmed.inl.gov/.
92
Radiation Source Protection and Security Task Force, report, 2006, section “Recovery of Lost or Stolen Sources.” A
74-day half-life results in the decay of about 99.9% of the material in 2 years (approximately ten half-lives).

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are more secure in the sense that there is now a defined program with security as its main
purpose,” but raised an issue of how security is defined: “It is unclear whether the sources
themselves are ‘more secure’ since there were no instances where subversive terrorist activity was
uncovered as a result of the [NRC] security program enhancements and no evidence that there
was a credible threat of theft or sabotage prior to the security enhancements.” RSOs attributed
much of the credit for increased security to orders from NRC. The Increased Controls (IC) order
of 2005 laid out the framework for actions required to boost security. Among other things, this
order required licensees to limit unescorted access to Category 1 and 2 sources to people the
licensee deemed trustworthy and reliable (T&R); monitor those sources, detect unauthorized
access, and respond promptly to such access; and have a pre-arranged response plan with local
law enforcement. An order of 2003 for panoramic irradiators of more than 10,000 curies directed
licensees to take specific security measures (that were not made public), and an order of 2006
required licensees to have the FBI fingerprint and review the criminal history record of people to
be granted unescorted access to Category 1 and 2 sources.93
Most RSOs said that the IC order made a great difference. It set out in general terms what needed
to be done, and gave RSOs a “very clear justification,” as one said, for requesting funds for
security upgrades. In response to the order, facilities installed security equipment, which varied
from site to site. Examples include the use of cameras and radiation detectors linked to a security
station to monitor rooms with radioactive materials, and use of key cards and stronger doors and
door locks to control access.
In another response to the IC order, RSOs worked with police officers to ensure an armed
response to a theft of a radioactive source. Police departments at several universities had sworn
officers who were armed. Most RSOs felt that the police could provide an armed response to an
alarm within a few minutes. In practice, though, one said, the response would depend on what
else the police were responding to at the time. Response time seemed less certain for small
facilities located away from major cities. RSOs said that the police understand the significance of
a radioactive source stolen by terrorists; some RSOs provided training on that topic, and in other
cases police took a course at the Y-12 National Security Complex (TN) offered by GTRI.
RSOs expressed divergent views on T&R investigations. Some saw the T&R requirement as “a
giant pain in the neck.” In this view, it is difficult to vet applicants, very few if any are rejected,
checks of personal references are of no value because the applicant provides the references, the
process takes an “inordinate” amount of time, and NRC guidance is unclear. Others saw the
requirement as quite manageable. At several facilities, RSOs organized a process for vetting
applicants, hired contractors to obtain the needed data, and had personnel who were skilled at
personnel evaluations decide if an applicant was T&R, and convened a committee meeting to
examine cases where T&R might be denied. One RSO said that the cost for each T&R
investigation was minimal, such as $100 for a local criminal history check and $32 for an FBI
background check. NRC has considered extending security measures for Class 1 and 2 sources to
Class 3 sources as well, though the idea has not gained traction. An RSO expressed concern that
if NRC extended T&R requirements to Category 3 sources, which are far more numerous than
Category 1 and 2 sources, the process would become extremely burdensome.
Each institution developed its own criteria for T&R. This was typically done in cooperation with
the organization’s HR office and, in the case of universities, with the university police
93

For references to these orders, see “Nuclear Regulatory Commission,” above.

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department. Criteria vary from one institution to another, but may include academic record; a
police and FBI background investigation and fingerprint check; personal references; and credit,
residence, and employment history. A few mounted a significant effort to define criteria. Several
said they had criteria but needed the flexibility to weight the significance of events in people’s
lives when deciding on T&R. Several said their T&R process looked for a pattern of behavior
rather than specific criteria. RSOs did not share their T&R criteria with RSOs from other
organizations because they saw the criteria as proprietary. As a result, an individual might be
declared T&R by one organization but not by another.
Some foreign graduate students and postdoctoral fellows seek T&R for unescorted access to use
equipment needed for their research. RSOs found it difficult to gather the requisite data.
Typically, students have college transcripts but not an employment history. It is difficult to gather
financial data, and if the student provided personal references, it is hard to judge their credibility.
Some information may be provided in foreign languages, adding another layer of difficulty.
Nonetheless, some universities were able to grant foreign nationals unescorted access; another
denied all foreign nationals unescorted access.
CRS inquired about the balance between prescriptiveness and flexibility of NRC orders. That is,
should orders prescribe uniform standards for source security, such as installing specific devices,
or should orders be performance-based, stating the desired outcome but leaving it to individual
facilities to select the means best suited to achieving that outcome? NRC opted for the latter in
the IC order. Some RSOs expressed frustration at the lack of clarity over what was needed to
meet that order. Should they buy certain equipment, and how much was too much or not enough?
Others felt that a performance-based approach provided flexibility. They noted that security
measures needed may vary even from room to room, such as whether a heavy irradiator is on the
first or fourth floor of a building. Requiring the same measures in all cases would, in this view,
lead to unnecessary expenses and would make it easier for terrorists to figure out what security
systems they would have to overcome at any facility. Another RSO said, “Performance-based
requirements are the only way that this program can be implemented in any reasonable manner.”
Since there are significant design differences even among facilities designed for the same
purpose, specifying a particular practice “would not necessarily be universally applicable.”
One way in which NRC could be prescriptive is to mandate that facilities be secure against a
“design basis threat” (DBT), which specifies in detail the type of threat that a facility must be able
to repel; a hypothetical example would be an attack by six terrorists armed with rocket-propelled
grenades and AK-47s, perhaps aided by insiders. NRC requires nuclear power plant operators to
be able to protect against a DBT to ensure adequate security. Several RSOs saw a DBT as
unnecessary and burdensome, requiring an “over-the-top” response. One who had dealt with
DBTs in another job felt that they produced “a multitude of scenarios” that led to “pretty bizarre
stuff.” Another felt that a DBT might be useful for guidance, but a high enough threat could force
facilities to close because it would become too costly to meet the threat.
Several RSOs were most concerned about an insider threat. An insider might kill others at the
facility, sabotage the facility, or help outsiders gain access to it. An insider familiar with the
security systems might be able to defeat them. CRS observes that T&R screening would not
necessarily foil this threat because T&R applies only to people needing unescorted access to
Category 1 and 2 sources, a category that often excludes most people at a facility.
RSOs who had worked with GTRI had high praise for the program: “They’ve been great.” “GTRI
did a fantastic job.” “The program evaluations that they have done meshed perfectly with the

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philosophy of the US NRC security requirements and provided a much needed independent
review and assessment of the facility program.” GTRI staff came to their facilities, provided a
security assessment, recommended a security plan, worked out with the RSOs and others (e.g.,
campus police) which security devices to install, and contracted with contractors to install the
devices. RSOs felt that GTRI staff were knowledgeable and professional. Examples of equipment
installed include: in-device delay mechanism to increase the time it would take for terrorists to
open an irradiator and steal its contents, thus providing more time for an armed response; iris
scanners, a biometric device to control access; cameras to monitor devices with radioactive
material; an infrared lighting system so people at central alarm stations could monitor radioactive
devices if the lights go out; a system to provide backup power if power goes out; and links from
alarms to police. Most felt that it was beneficial to have an outside group evaluate their security
situation. One said that without the program his facility would not be upgrading security and
pointed to a side benefit he expected from the upgrade, which was then in progress: A robust
security system of the sort GTRI will install will send a message to people using the facility that
security is important and they must follow guidance, helping instill a security culture. On the
other hand, one RSO felt that some of the security measures seemed excessive, while another said
that the added measures went a step beyond the real threat.

Detecting Radioactive Sources
U.S. Customs and Border Protection, a component of the Department of Homeland Security
(DHS), has deployed systems at ports and border crossings to detect and identify radioactive
material entering the United States. (Customs and Border Protection also screens people and
goods entering the United States for guns, drugs, and other contraband.) In addition, other DHS
components, notably the Coast Guard, Transportation Security Administration, and Office of
Border Protection, deploy radiation detection equipment at other sites inside the United States,
and the Domestic Nuclear Detection Office has a cooperative program with state and local
agencies to deploy such equipment.
Deployed systems seek to detect terrorist nuclear weapons or nuclear-weapon material while
minimizing the impact on legitimate commerce, but are of use for interdicting some potential
RDD material as well. They are of two main types, passive radiation detection systems and
radiography systems. (Radiography systems send a beam of x-rays or gamma rays through a
cargo container or other item to be inspected to create a radiograph, an image similar to a medical
x-ray.) As noted earlier, some types of RDD-usable materials are strong gamma-ray emitters. In
contrast, nuclear weapon materials (certain isotopes of uranium and plutonium) give off fewer
gamma rays that are, on average, much less energetic. As a result, currently-deployed radiation
detectors, such as radiation portal monitors,94 could easily detect RDD-usable material if
unshielded. Therefore, such material would in all likelihood be shielded, and even a tiny amount
would require heavy shielding. A thick enough layer of lead would stop enough gamma rays to
preclude detection by radiation detectors, but a thicker shield is more likely to be visible as an
area of dense matter on a radiograph.
Efforts are underway at national laboratories, universities, and corporations in the United States
and other nations to improve existing detection technologies and to develop new ones based on
94

See U.S. Department of Homeland Security. Customs and Border Protection. “Radiation and Portal Monitors
Safeguard America from Nuclear Devices and Radiological Materials,” no date, accessed July 15, 2010,
http://www.cbp.gov/xp/cgov/border_security/port_activities/cargo_exam/rad_portal1.xml.

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different physical principles. The science of detection and nine detection technologies are
discussed in detail in CRS Report R40154, Detection of Nuclear Weapons and Materials:
Science, Technologies, Observations, by Jonathan Medalia.
Since detection systems offer a high probability of detecting RDD-usable material within their
range, terrorists intent on an RDD attack would try to evade detection. Very little shielding would
render small alpha and beta sources undetectable. It would be difficult for technical means to
detect radioactive material smuggled across unguarded stretches of the U.S. border; interdiction
in that scenario would depend on border security. Terrorists could avoid detection equipment at
ports of entry by obtaining radioactive material within the United States. Radiation detectors are
deployed along some major highways and choke points (e.g., bridges) within the United States;
terrorists could transport RDD material along routes without detectors if they knew where
detectors were located. The United States takes technical and other measures in response. A
struggle between offense and defense, or between hiders and seekers, is a common military and
homeland-security issue.

Intelligence and Counterterrorism
To thwart terrorist attacks using CBRN weapons, intelligence must be collected, analyzed, and
acted upon. This section notes some U.S. government agencies involved in this effort and what
they do. A more detailed description is beyond the scope of this report, and descriptions of RDDspecific intelligence and counterterrorism efforts would involve classified information. It is also
beyond the scope of this report to delve into shortcomings or improvements in intelligence
collection, analysis, and sharing, or in the ability to act on intelligence. Several CRS reports
provide additional information.95
Many U.S. government agencies contribute and analyze intelligence on potential CBRN terrorist
threats. However, in its analysis of intelligence and other failures preceding the 9/11 attacks, the
9/11 Commission noted shortcomings in the Intelligence Community and recommended unity of
effort “across the Foreign-Domestic Divide,” “in the Intelligence Community,” “in Sharing
Information,” and “in the Congress.”96 In response, Congress passed the Intelligence Reform and
Terrorism Prevention Act of 2004 (IRTPA, P.L. 108-458). This act established the position of
Director of National Intelligence (DNI), who is to “serve as head of the intelligence community”
and “act as the principal adviser to the President, to the National Security Council, and the
Homeland Security Council for intelligence matters related to the national security.”97 Section
6905, “Radiological Dispersal Devices,” makes it unlawful to acquire or possess RDDs.
Some agencies focus on intelligence outside the United States. IRTPA established the National
Counterterrorism Center (NCTC, Section 1021) and directed the President to establish the
National Counter Proliferation Center (NCPC, Section 1022). According to IRTPA, the NCTC is
95

See CRS Report R41022, The National Counterterrorism Center (NCTC)—Responsibilities and Potential
Congressional Concerns , by (name redacted) CRS Report RL33539, Intelligence Issues for Congress, by (name re
dacted); CRS Report RL34231,
Director of National Intelligence Statutory Authorities: Status and Proposals, by
(name redacted) and (name redacted); and CRS Report R41004,
International Terrorism and Transnational Crime:
Security Threats, U.S. Policy, and Considerations for Congress, by John Rollins and Liana Sun Wyler
96
National Commission on Terrorist Attacks upon the United States, The 9/11 Commission Report, New York, Norton,
2004, p. vii.
97
For further information, see U.S. Office of the Director of National Intelligence, “ODNI Fact Sheet,” October 2010,
http://www.dni.gov/content/ODNI%20Fact%20Sheet_Oct2010.pdf.

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“to serve as the primary organization in the United States Government for analyzing and
integrating all intelligence possessed or acquired by the United States Government pertaining to
terrorism and counterterrorism, excepting intelligence pertaining exclusively to domestic
terrorists and domestic counterterrorism.” It is “to conduct strategic operational planning for
counterterrorism activities, integrating all instruments of national power, including diplomatic,
financial, military, intelligence, homeland security, and law enforcement activities within and
among agencies,” though the NCTC director “may not direct the execution of counterterrorism
operations.” It is also “to serve as the central and shared knowledge bank on known and
suspected terrorists and international terror groups.”98 The NCPC is to be “a primary organization
within the United States Government for analyzing and integrating all intelligence possessed or
acquired by the United States pertaining to proliferation.”99
Within the United States, the Federal Bureau of Investigation (FBI) is the lead agency for
counterterrorism intelligence. This authority derives from several sources. The U.S. Code (Title
18, Section 2332b(f)), gives the Attorney General “primary investigative responsibility for all
Federal crimes of terrorism.” The Code of Federal Regulations states that the FBI Director “shall
… [e]xercise Lead Agency responsibility in investigating all crimes for which it has primary or
concurrent jurisdiction and which involve terrorist activities or acts in preparation of terrorist
activities within the statutory jurisdiction of the United States. Within the United States, this
would include the collection, coordination, analysis, management and dissemination of
intelligence and criminal information as appropriate.”100 Homeland Security Presidential
Directive 5 states, “Generally acting through the Federal Bureau of Investigation, the Attorney
General, in cooperation with other Federal departments and agencies engaged in activities to
protect our national security, shall also coordinate the activities of the other members of the law
enforcement community to detect, prevent, preempt, and disrupt terrorist attacks against the
United States.”101 A congressional report observes, “the FBI created a Directorate of Intelligence
in its headquarters to produce intelligence analysis and to provide an institutional home for its
analysts. In an effort to create this so-called ‘agency within an agency,’ the FBI created a National
Security Branch at its headquarters composed of its Counterterrorism and Counterintelligence
Divisions and the new Directorate of Intelligence.”102

Global Efforts
Securing Radioactive Sources
Because an RDD attack might occur outside the United States, or material obtained abroad might
be used for an RDD attack on this nation,

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/crs%3AR41890. Public record. Not legal advice.