Sealed Radioactive Sources
Radiation Source Reduction & Management
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- Common Industrial Uses
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Sources, often called "sealed sources," are usually small metal containers in which a specific amount of a radioactive material is sealed. Specialized industrial devices, such as those used for measuring the moisture content of soil and for measuring density or thickness of materials, take advantage of the unique properties of radionuclides.
Sources are usually enclosed in a housing that prevents the escape of the radiation. As long as they remain sealed and the housing remains intact and the devices are handled and used properly, the devices present no health risk from the radioactive source within. In fact, manufacturers of these devices must demonstrate protectiveness in order to receive a license to manufacture and sell them. Purchasers of the devices must be licensed to use the device in the intended manner, and are required to safely and legally dispose of the sources.
EPA's source reduction and management activities seek to reduce the public health and environmental impact of sealed radiation sources by substituting alternative technologies, tracking existing sources as they move through the economy, preventing their entry into the metal supply or the environment, and returning orphaned sources to regulatory control.
On this page:
- What do sealed sources look like?
- How dangerous are sealed sources?
- What are radioactive sources used for? Which radionuclides are used in these sources?
- Which industries use sealed sources, and what are they used for?
- Orphan Sources: What are 'orphan' sources?
- Have sources actually contaminated metal that was recycled?
- Can't scrap metal recyclers find the sources with a radiation detector and just collect them?
- What is EPA doing about this problem?
- Who else is working on this problem?
What do sealed sources look like?
Radioactive sources come in a variety of shapes and sizes, from "button sources," used for calibrating instruments, to huge sources used in research:
How dangerous are sealed sources?
The International Atomic Energy Agency has developed a ranking of radioactive sources according to their relative potential to cause immediate harmful health effects if not safely managed or securely protected. Individual sealed sources are ranked from highest potential (category 1) to lowest potential (category 5).
These sources could lead to the death or permanent injury of individuals who are in close proximity to the source for a short period of time (minutes to hours). Examples: radioisotope thermoelectric generators, irradiators, teletherapy machines, and fixed multi-beam teletherapy machines.
These sources could lead to the death or permanent injury of individuals who are in close proximity to the source for a longer period of time than for Category 1 sources.
Examples: industrial gamma radiography equipment and high/medium dose-rate brachytherapy.
These sources could lead to the permanent injury of individuals who are in close proximity to the source for a longer period of time than Category 2 sources. Sources in Category 3 could, but are unlikely to, lead to fatalities.
Examples: fixed industrial gauges (level gauges, dredger gauges, conveyor gauges, and spinning pipe gauges) and well logging gauges.
These sources could lead to the temporary injury of individuals who may be in close proximity to the source for a longer period of time than Category 3 sources. Permanent injuries are unlikely
Examples:low dose-rate brachytherapy sources, thickness gauges, portable gauges, and bone densitometers.
These sources could, but are unlikely to, cause minor temporary injury of individuals.
Examples: X-ray fluorescence devices, static eliminators, and electron capture devices.
- Sealed Radioactive Sources: Uses and Risks. International Atomic Energy Agency. Accessed 06/11/07.
This page provides an overview of the uses and hazards of sealed radioactive sources.
What are radioactive sources used for? Which radionuclides are used in these sources?
Radioactive sources are used in devices for measuring industrial process parameters, such as moisture and thickness of products and for monitoring equipment condition such as pipe corrosion. Radioactive source devices are also used as power sources. You can see a more complete list of their uses on the page, Common Industrial Uses of Radioactive Sources.
Approximately 25 different radionuclides are used in industrial and medical applications. You can read about the major radionuclides on the page, Radioisotopes Commonly Used in Industry.
Which industries use sealed sources, and what are they used for?
EPA has begun the process of evaluating some of the most common applications of sources to identify the potential for developing alternative technologies and vulnerability for loss of sources. You can read about how industry uses different radionuclides on the page, Common Industrial Uses of Radionuclides.
Orphan Sources: What are 'orphan' sources?
After studying each of the potential ways in which the metal can become contaminated with radioactivity, EPA determined that lost, abandoned, or stolen radioactive sources and imports of foreign metals are the most likely origins of contaminated metals in this country.
If equipment containing a sealed source is disposed of improperly or sent for recycling as scrap metal, the sealed source will fall out of regulatory control and may end up in a metal processing facility or in the possession of someone who is not licensed to handle the source.
Specially licensed sources bear identifying markings that can be used to trace them to their original owners. However, some sources do not have these markings or the markings are damaged and become unreadable. In these cases, the sources are referred to as 'orphan sources' because no known owner can be identified.
If a steel mill melts a source, it can contaminate the entire batch of metal, the processing equipment, and the facility. More importantly, it can result in the exposure of workers to radiation.
Have sources actually contaminated metal that was recycled?
Yes. According to a 1999 study in IAEA Bulletin, (Vol. 41, No. 3 ,pg. 23) , there were at least 30 recorded accidental melting of radioactive material in the United States between 1983 and 1998 . (The article is available on-line in PDF format. (4 pp, 56K About PDF)
Melted sources can contaminate an entire batch of metal at a steel mill. This introduces the potential for radioactively contaminated metal to be made into consumer products. Decontaminating a steel mill once a source has been melted is extremely expensive, averaging $12-15 million, and causes additional unnecessary human health risks.
A cesium source was melted at a steel mill in Florida. The source was vaporized and drawn into the mill’s emission control system where it contaminated the bag house dust. Radiation alarms in the primary emission control system bag house lead to shutting down the emission system. As a result, contaminated flue dust backed up into the secondary bag house. To remove the contamination and return the plant to production, decontamination workers and health physics technicians worked around the clock for more than three weeks in extreme heat. The total estimated cost for the melted source was $25 million.
Can't scrap metal recyclers find the sources with a radiation detector and just collect them?
Scrap yards and disposal sites attempt to detect orphan sources and other contaminated metals by screening incoming materials with sensitive radiation detectors before they can enter the processing stream and cause contamination. Unfortunately, the protective housings that make the sources safe, also make detection extremely difficult. Further, if the source is buried in a load of steel, the steel acts as further shielding, making detection difficult by today's radiation detection devices. Consequently, there is always a potential for sources to become mixed with and contaminate scrap metal. EPA is following closely research into improved detection capabilities that can help scrap recyclers detect sources before they cause harm.
What is EPA doing about this problem?
EPA has developed voluntary programs and training to help reduce the incidences of orphaned sources in scrap metal and the potential for exposure of workers and the public and contamination of the environment. The Alternative Technologies Initiative supports the replacement of sealed sources in devices with non-nuclear alternatives to reduce the number of sources in the economy. EPA has also developed training for specific areas in which training can help reduce the opportunity for sealed sources to cause harm.
Who else is working on this problem?
Nuclear Regulatory Commission (NRC)
NRC is increasing regulatory control and increasing frequency of inspections and fines resulting from mishandling of licensed sources. The Agency is also developing a database to track sources. Neither the National Radioactive Source Database nor NMED (Nuclear Materials Events Database), which tracks lost sources, will be available to the public. NRC has also developed a poster with photographs and descriptions of different kinds of sealed sources.
Conference of Radiation Control Program Directors(CRCPD)
CRCPD manages a Nuclear Regulatory Commission funded program for disposing of recovered orphan sources: CRCPD National Orphan Radioactive Material Disposition Program CRCPD and DOE/NNSA have created a program entitled "Source Collection and Threat Reduction" or "SCATR" to collect sources being stored and not used that could - as an aggregate - be used for malicious intent. DOE recognizes that the availability of disposal of such sources is limited and expensive; and has initiated this rare opportunity for licensees to have financial assistance in properly securing and disposing of these sources through this CRCPD program
- State of Florida
The State of Florida has been selected to participate in this pilot project (PDF) (3 pp, 340K About PDF)
Department of Energy (DOE)
DOE is providing disposal of found orphan sources through its Off-Site Source Recovery Program, which is managed at DOE's Los Alamos National Laboratory.
Department of Transportation (DOT)
Department of Transportation regulates the shipment of radioactive sources
Occupational Safety and Health Administration (OSHA)
OSHA regulates exposure to radioactivity in the workplace.
- Radioactive Source Recovery Efforts
This page describes the recovery efforts of governments, industries, and other organizations