March/April 1992
Naturally occurring radioactive materials are a growing concern for scrap recyclers and consumers. Here's how to prevent what you don't know from hurting your business.
BY MICHAEL MATTIA
Michael Mattia is director of risk management for the Institute of Scrap Recycling Industries (Washington, D.C.).
Scrap recyclers have long known the time, effort, and costs that go into processing and shipping a railcar of scrap to a consuming mill. Nowadays, many are also learning what it's like for a load to be rejected and returned, at their expense, because it's contaminated with naturally occurring radioactive material, or NORM.
The increase in detection of NORM-containing scrap may make it appear that the problem is new and growing steadily, but the truth is that NORM has always been in scrap. In the past it simply went undetected; but as more and more scrap consumers of all types purchase radiation detection monitors or improve their current detection systems, the situation is changing. Nevertheless, scrap recyclers can prevent NORM from hurting their businesses and employees by installing their own detection systems and learning the basics of NORM and other radiation sources.
Radiation, in its many forms, comes from the sun, the earth, heat sources such as fires, even from our bodies. When people refer to the hazards of radiation, however, they are speaking about ionizing radiation, which is created when an element becomes unstable and gives off ions—or charged particles—in an attempt to become more stable. These ions, usually described as alpha, beta, or gamma radiation, pass through air and matter but aren't necessarily harmful; the damage depends on the degree of exposure.
Radiation can appear naturally, as in NORM, or be created artificially through accelerators and elements such as uranium, thorium, and plutonium. NORM is created as isotopes of uranium and thorium decay, becoming what is called the daughter element of these isotopes. Two common NORM isotopes, radium and radon, are daughter elements of uranium. All soils and rocks contain some amounts of NORM, and they account for varying levels of the background radiation that is around us at all times.
Artificial radiation is often used for energy generation or in equipment such as industrial gauges, calibrators, and scanners; medical X-ray and chemotherapy units; even household smoke detectors. Such equipment, which usually carries a warning label about its radioactive components, rarely ends up in the scrap stream. Although a handful of these sources have contaminated U.S. mills and smelters, requiring costly cleanups, there have been no incidents of serious exposure of scrap or mill employees in the United States .
Scrap recyclers are much more likely to run across scrap contaminated by NORM. The extraction, purification, and consumption of minerals, fossil fuels, and metals can concentrate NORM deposits on the equipment and in the wastes associated with these processes. Pipes used in the oil and gas industries, for instance, can come into contact with uranium sources or develop a layer of radioactive radium scale or sludge on its inner surface. NORM can also be found in slag and flue dust from ferrous metal production, among other sources. (See Table 1 for a list of some common scrap items that could be NORM-contaminated.)
Reducing the Risk of Exposure
Employees of scrap companies can be exposed to radiation externally and internally when handling or working near contaminated scrap. The potential for hazardous external exposure to NORM is generally low because NORM usually appears in low concentrations and the radioactivity is often partially shielded by the scrap in which it is found. Employees can further decrease the degree of external exposure by decreasing the time spent near the radioactive source and increasing their distance from the material. According to the inverse square law for radioactivity, moving 2 feet away reduces the exposure to one-fourth of the original exposure, moving 3 feet away reduces the exposure to one-ninth, and so on.
The potential for hazardous internal exposure to NORM, on the other hand, can be high. NORM can enter the body through inhalation, ingestion, or wounds, so employees should not eat, drink, or smoke while handling potentially contaminated scrap. In addition, they should wear gloves during handling and should wash their hands, shower, and change clothes after working with these materials.
Radioactive scale and sludge on contaminated scrap also poses a concern in that it, can be separated from scrap material during processing, allowing for potential contamination of a scrap company's buildings, grounds, equipment, and residue streams.
Consumers' facilities, equipment, products, and employees can likewise be contaminated if NORM-contaminated scrap enters their operations undetected. When such scrap is melted, the NORM isotopes will generally accumulate in the slag, although they can also be found in the flue dust or the finished metal. Detecting and removing the contaminated pieces of scrap before processing or smelting is the only way to eliminate these concerns.
Detection Protection
To reduce their risk of exposure, scrap recyclers that could deal with NORM-contaminated scrap—which encompasses almost everyone—should monitor all materials entering and leaving their facilities. Monitoring systems for scrap recycling operations need to be highly sensitive to pick up the low levels of radiation that can be emitted by both NORM and more hazardous—and often shielded—sources. Contaminated scrap can easily be buried in the center or at the bottom of a large load and may be transported in a trailer or railcar that further shields the radiation from detection.
To implement an effective detection program, scrap recyclers must consider the materials they handle, the way they process their materials, and their method of transport. These factors are also important to selecting proper detection equipment. Portable detection monitors are usually adequate in facilities that handle small quantities of potentially contaminated scrap.
Facilities that process substantial tonnages of potentially contaminated scrap, however, will probably want to consider installing fixed detectors, which should be able to detect medium- and high-energy gamma-emitting isotopes and neutrons buried in a load of scrap and should be able to detect the radiation through the walls of a transport container. To decrease the probability of false readings, the detector should be capable of monitoring background radiation and adjusting its reading of the scrap load to compensate for these levels.
Fixed detectors should be positioned to provide optimal scanning of an average load. For example, detectors used to survey trucks could be installed on both sides of the plant's entrance or scale, while detectors for railcars might best be set overhead to avoid shielding problems created by the containers' thick walls.
Portable detectors should complement an operation's fixed detectors, helping to pinpoint the source of an alarm. If a scintillating fixed detector is used, a scintillating portable detector should also be used; otherwise, the portable detector may not be capable of isolating the source of radioactivity found by the fixed detector. In addition, portable detectors should have multiple sensitivity settings to fit different circumstances, a visual display, an audible alarm, and several monitoring wands to suit different situations. If the detector will be used on trailers or railcars, for instance, the surveyor should use a long wand to reach all areas of the vehicle. It is also recommended that the portable detector have a rechargeable battery pack to ensure a charged power source whenever the detector is needed.
Heeding an Alarm
Once you install radiation detection equipment, it's likely that it will eventually alarm, false or not. The following procedures are recommended when a detector alarms:
- Move the load from the monitoring area, reset the detector, and monitor the load again.
- Isolate the load and determine the ambient background radiation levels in the monitoring zone.
- If appropriate, scan the driver and detachable motor vehicle with a portable detector.
- Slowly scan all exterior surfaces of the container with a portable detector. For best detection results, the portable detector should be held less than 2 inches from all surfaces.
- Mark the surfaces where levels of radioactivity are detected. Note on a diagram of the container the areas where radioactivity is detected and the levels found.
- Survey individual scrap pieces, starting with those closest to the areas of the container with detected levels.
- Survey the interior of the container. Welds, dirt, and surfaces can be potential areas of contamination. If, at any time, the detected levels exceed the highest level on the detector, the survey should be stopped immediately and the appropriate state office for radiation protection should be notified.
- Isolate the materials, containers, or equipment with detected levels of radiation. Notify the appropriate state office.
- If radioactive materials, containers, or equipment must be moved off the premises, notify the appropriate state office to obtain the necessary exemptions and permits concerning Department of Transportation safety standards.
The Regulatory Void
The federal government—through the Nuclear Regulatory Commission (NRC)—and 28 states tightly regulate and license the use of radioactive source materials such as uranium and thorium, special nuclear materials such as plutonium, and radioactive byproducts of nuclear material and the ores of source materials. The NRC and most states also set limits for radiation exposure to the public, which includes employees of scrap facilities.
In contrast, the NRC has no regulations for NoRM or accelerator-produced radiation. In fact, the agency, has specifically excluded radium—a major NoRM source—from its regulations, relegating it to the Environmental Protection Agency (EPA) and states. Nevertheless, Louisiana is the only state that regulates NoRM contamination in scrap from oil and gas fields, and Texas is reportedly close to passing similar regulations. other states are considering NoRM regulations under the guidance of the Conference of Radiation Control Program Directors (CRCPD) (Frankfort, Ky.).
Part of the regulatory problem is that, unlike artificially created radiation, NoRM is a natural phenomenon, so it is impossible to regulate at the source. The best the EPA and states can do is regulate the handling and/or disposal of it after it is found in materials and set limits on acceptable amounts of NoRM in new products. This can be difficult: When the contamination is dispersed within or mixed with other materials, assessing the radiological impact may be close to impossible. In such cases, guidance on the allowable concentration of radioactive material must be handled on a case-by-case basis, taking into account existing standards for radiation protection, the level of radioactivity, and the level of contact the public would have with the material.
Some scientists suggest that new steel can safely contain a certain percentage of NoRM-contaminated scrap, but this theory has not been proved and steel mills are understandably hesitant to take any risks. Hence, they categorically reject any scrap load that contains radioactive material. The Petroleum Environmental Research Forum, a consortium of gas and petroleum companies, however, is currently examining the safety and practical considerations of recycling gas and oil scrap and equipment, seeking to establish parameters in this case. The scrap metal radioactivity committee of CRCPD is also reviewing this question.
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NoRM will continue to be a concern of the scrap recycling industry, and scrap recyclers should view it not as an unseen force to be feared but as a natural and manageable aspect of business. The increase in NoRM detection, in fact, can be seen as a positive development in that it is helping to safeguard scrap recyclers and consumers from the potential dangers of radioactive scrap. If scrap companies make the effort to detect and extract NoRM materials from the scrap stream, they can alleviate worries about these materials and upgrade their end product to the benefit of all.
Table 1
Potentially NoRM-Contaminated Scrap
Scrap Material Common Sources
Cement Building demolition
Ceramic tile
Equipment, vessels, pipe Geothermal energy exploration
Mining and processing of aluminum,
bauxite, coal, copper, phosphate,
tin, titanium, and zinc ores
oil exploration/processing
Natural gas exploration/processing
Phosphogypsum production
Sanitary or storm-water sewers
Water treatment
Fuel pumps, tanks oil, propane
Glass enamel
Glassware, glass brick,
glass pane
Glazed ceramic tableware
Industrial boilers
Stainless steel Phosphoric acid manufacturing
Naturally occurring radioactive materials are a growing concern for scrap recyclers and consumers. Here's how to prevent what you don't know from hurting your business.