Radiation Detection/Safety In Scrap Processing

Approximately 50 percent of today's metal is recycled. This is because secondary source (scrap) metals are just as good as a primary source (raw) metal. Using scrap metal also helps to save money as scrap metal is cheaper than the raw materials. Recycling metals also helps by saving resources and reducing landfills and mineral reserves. Although scrap metal is excellent to use, there also exists risks. The main risk is the great potential for accidents where hazardous materials present in scrap cause death, injury, and other damages. This is mainly radioactive scrap metal. Radioactive scrap metal is where radioactivity enters the metal either intentionally or not, and through natural occurrences. These can come from decommissioned nuclear reactors, nuclear weapons, the oil and gas industry, contaminated buildings, and other various sources. Imported scrap metal also presents radioactivity as well.

There are two main types of radiation sources, sealed sources and orphan sources. Sealed sources are mainly small metal containers in which a specific amount of a radioactive material is sealed inside. Examples of these are calibration sources, source capsules, industrial sources, and radium needles. Orphan sources are also sealed sources, but one that have become lost, disposed of improperly or sent for scrap recycling when they should have been taken care of. Most orphan sources come from imported scrap metal. An example of an orphaned source contamination is the Goiania accident that happened in Brazil on September 13, 1987. The accident was the result of an old radiation source scavenged from an abandoned hospital. This radiation contamination killed four people, injured twenty-eight, and produced more than 200 cases of radiation poisoning. Approximately 200 lost sources are reported each year.

What are the chances of radioactive scrap? One of the main reasons for radioactive scrap is the accidental melting of a radioactive metal or material and since 1982 about 50 of these accidents have been reported. The problems caused by radioactive scrap are both cost and health related. When a radioactive material is melted into a batch of metal, the whole batch becomes contaminated. This means the entire batch can no longer be used and must be discarded, preferably immediately. The cost to decontaminate a steel mill averages anywhere from twelve to fifteen million dollars or more. This decontamination cost includes cleanup, downtime, and disposal cost. Most places must shut down production for weeks to clean up the mess. There is also health risk included when melting of a radioactive material occurs. The main problem with a melted piece of radioactive material in a batch is not the metal or material itself, but actually the slag, furnace dust, fly ash, and other emissions produced from the batch of molten metal. The workers can inhale the radiation in and cause serious health problems. There is also the potential of the air circulating and being vented to the outside world therefore contaminating more people than just workers. Besides contaminated air, there is also the risk of touching the contaminated material and causing radiation burns. Neurological problems are also another health risk to workers, since radiation can affect the brain and how it works. These health risks can seriously injure or even kill people that come in contact with radioactive sources in scrap metal.

The best way to prevent radioactive scrap metal and the problems it causes is to prevent the entry of radioactive material into the metal supply. The best way to accomplish this is by having effective laws and regulations. Although there is no set amount of "safe" radiation or the smallest amount of radiation allowed, having some sort of regulations help. International trade laws also help to stop the contamination of imported scrap metal. Another way of preventing the radioactive material entering the recycling stream is by training and making workers aware of the risks associated with radiation and safety precautions to take. Companies should have seminars and lectures to educate their workers on the dangers of radiation in scrap metal and what safety arrangements they should take to ensure no accidents occur. This precaution is very vital to the prevention of accidents involving radioactive scrap metal. Other ways to reduce public and environmental impact of sources is to substitute alternative technologies, regulate the materials and activities of contaminated scrap metal, and to return lost sources to regulatory control when found.

While prevention is needed and does help lower the accidents, it is not 100 percent effective in stopping all scrap from being radioactive free. Therefore measures of detection are needed. The best way to detect radioactive scrap metal is to have regular and well-established checks using radioactive detection instruments. This goes along with having rules and regulations for radioactive scrap metal. Detection instruments are widely available and can be classified as portable or fixed. Portable devices can be used as a primary defense or can be used to just located and determine the concentration of radiation in the scrap metal. Portable devices are usually less expensive than the fixed devices, mainly because they are not as sensitive. Fixed detection instruments are very sensitive and usually do not rely on an operator as much as the portable devices. The only problem with fixed devices is that they only detect if radiation is present in the scrap metal and cannot tell the difference in intensity of the radiation. The fixed instruments are usually very expensive running anywhere from 1 to 100 thousand dollars. Although they are very expensive, fixed detection equipment is not 100 percent. The radioactive scrap metal may be shielded by other scrap and/or its own castings. The fixed equipment machines may also give false alarms at times. There are many materials that carry small amounts of radiation that may set off alarms set by the detector. The best option for using detection equipment is to use a mixture of both the fixed and portable instrumentation. Besides monitoring instruments, labels for radioactive sources and containers are also used to detect the level of radiation in materials. With these ways of detecting radiation, it is also best to keep pristine records of everything, especially when radioactive material is involved.

Radiation in scrap metal comes from various sources. While there are multiple ways to prevent and detect radiation, no method will ever be 100 percent effective. Radioactive scrap metal and radiation sources can create both health and cost risks to companies and their workers. Worker training and procedures need to be in place to help detect radioactive sources and how to properly remove of them. Proper radiation detection instruments can help detect the radiation but once again, are not always effective at catching everything.

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