Q & A: Safety and Security of Radioactive Sources
- What are radioactive sources?
- What are "orphan sources"?
- How many radioactive sources are there worldwide?
- When are radioactive sources hazardous?
- Are radioactive sources being smuggled?
- Can radioactive sources be detected?
- What´s a "dirty bomb" and how dangerous could it be?
- Is there legislation controlling the security of radioactive materials?
- What´s the IAEA doing to combat these safety and security problems?
- How do radioactive sources look?
Radioactive sources are used throughout the world for a wide variety of peaceful and productive purposes in industry, medicine, research and education, and in military applications. These sources utilize radioactive materials that are firmly contained or bound within a suitable capsule or housing; although some sources involve radioactive materials in an unsealed form.
Until the 1950s, only radionuclides of natural origin, particularly radium-226, were generally available for sources. Since then, radionuclides produced artificially in nuclear facilities and accelerators have become widely available, including cobalt-60, strontium-90, caesium-137 and iridium-192.
Radioactive sources vary widely in physical size and properties, the amount of radiation they emit, and type of encasing. Some are portable instruments, such as gauges for taking measurements, while others are fixed pieces of equipment, such as a radiotherapy machine for cancer treatment.
The IAEA has categorized radioactive sources, to identify those types that require particular attention for safety and security reasons. Most significant are certain industrial and medical radioactive sources - typically cobalt-60, caesium-137, strontium-90, and iridium-192 - that emit high levels of radiation.
When safely used and regulated, the social and economic benefits from the many applications of radioactive sources are high, in the billions of dollars worldwide each year.
Radioactive sources that are outside of regulatory control are called "orphan sources" for short. They may never have been subject to regulation, or they may have been regulated initially but then were abandoned, lost, misplaced, stolen, or removed without authorization. Some sources may not be formally "orphaned" but their control may be weak and therefore vulnerable to being mishandled or lost.
Through its efforts to help countries improve their national infrastructures for radiation safety and security, the IAEA has found that more than 100 countries (not all of them IAEA Member States) may have inadequate control and monitoring programmes necessary to prevent or even detect the theft of radiation sources. Half of these countries with urgent needs - 52 in Africa, Asia, Latin America, and Europe - are making progress through an IAEA project to strengthen their capabilities to control and regulate radioactive sources.
Millions of radioactive sources have been distributed worldwide over the past 50 years, with hundreds of thousands currently being used, stored, and produced. Worldwide, the IAEA has reported on specific applications: more than 10,000 radiotherapy units for medical care are in use; about 12,000 industrial sources for radiography are supplied annually; and about 300 irradiator facilities containing radioactive sources for industrial applications are in operation.
In normal and regulated use, radioactive sources pose no undue radiological hazard to workers or the public. Problems can arise if radiation sources are involved in accidents, and if they become damaged or lost. Some of these sources contain large amounts of radioactive material and have the potential to cause serious radiological harm if they were involved in accidents or used in malicious acts.
The IAEA has assisted countries in responding to emergencies involving radioactive sources that caused deaths or injuries. The incidents have intensified efforts to solve problems and ensure the application of international standards on radiation safety and security developed by the IAEA and partner organizations. IAEA programmes are helping countries to share experience and to apply the standards, but more needs to be done.
Over 70 States have joined with the IAEA to collect and share information on trafficking incidents involving both radioactive sources and other radioactive materials, including nuclear materials. The IAEA's Illicit Trafficking Database database contains information reported and confirmed by States.
Radioactive sources can be detected and their movement monitored. The effective detection range depends on the amount and type of radiation emitted by the source and also on the possible presence of shielding materials that may reduce the amount of radiation that reaches the detector.
Fortunately, the most intense and dangerous sources normally are the most susceptible to detection. Several types of advanced instruments already are in use for detecting radioactive materials. More advanced systems are under development that will be more sensitive, easier to use, or more capable of dentifying exactly what kind of radioactive materials are present.
Advanced detectors currently in use include:
- Portable Detectors. Instruments using an inorganic or a plastic scintillator as detector are being used and developed. They may include a multi-channel analyser for gamma spectroscopy to identify radioactive materials emitting gamma rays.
- Fixed Detectors. These types of monitors are designed for border control points, airports, and other ports of entry. They typically include alarms and display instrumentation and are automated to enable screening of people, luggage, or vehicles. In addition to a capability to detect gamma radiation, many are equipped with neutron detectors that can help in detection of plutonium.
A dirty bomb contains radioactive material, but does not use that material to produce a nuclear explosion, as is the case with a nuclear weapon. A dirty bomb -- also known as a "radiological dispersion device" or RDD -- would be constructed of conventional explosives and radioactive material, the detonation of which would result in the dispersion of the radioactive material contained in the bomb. As with any explosion, people in the immediate vicinity could be killed or injured by the blast itself. The dispersed radioactive material could lead to exposure of people in the vicinity.
It is difficult to predict the level of exposure of persons, as this would depend on many factors such as the physical and chemical form of the radioactive material, size and type of explosive and proximity of persons to the blast. What is more likely is that persons could be exposed to low levels of radiation that would slightly increase their risk of cancer in the long-term. Other effects of a dirty bomb could include the social disruption associated with the evacuation, the subsequent clean-up of contaminated property and the associated economic costs.
The International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources (the 'BSS'), IAEA Safety Series 115, published in 1996, includes requirements relating to the security of sources. While the security requirements relate to prevention of theft and unauthorised use, they do not specifically consider malicious acts by terrorists. The BSS are binding only on those States that choose to adopt them, or are receiving assistance from IAEA. Revising the BSS would be a major undertaking, so the IAEA is in the process of developing other guidance documents to specifically cover the security of radiation sources.
The Code of Conduct on the Safety and Security of Radioactive Sources includes requirements relating to the security of sources. Although the IAEA General Conference has invited Member States to take note of the Code and to consider, as appropriate, means of ensuring its wide application, it is not a legally binding document. The Code was published prior to the events of 11 September 2001, and it is to be reviewed later this year at an IAEA Technical meeting to determine, amongst other things, how it can be enhanced with regard to security. The status of the Code is also being reviewed, as some Member States have called for an internationally binding instrument on the Safety and Security of Sources.
A multi-faceted plan of action is in place. High priority is attached to radioactive sources, illicit trafficking, and other aspects of nuclear security. The IAEA has categorized radioactive sources to identify those types that require particular attention for safety and security reasons. The IAEA is also assisting countries in responding to emergencies involving radioactive sources that may cause deaths or injuries or be security problems. The incidents have intensified efforts to solve problems and ensure the application of international standards on radiation safety and security developed by the IAEA and partner organizations.
The IAEA has taken the leading role in the United Nations system in establishing standards of safety, the most significant of which are the Basic Safety Standards and the more recent Code of Conduct on the Safety and Security of Radioactive Sources. These guidelines promote consistent international approaches to radiation protection, safety and security.
Radioactive sources come in various shapes and sizes. The international radiation symbol is used to indicate that the source is regulated as hazardous material.