May/June 2009
Radiation in scrap is a growing concern due to the proliferation of orphan sources and more screening at ports. New technologies—along with the proper training—can help keep scrapyards and their workers safe.
By Chelan David
Radiation detection would be easier if radioactive materials were green and glowing, as they appear in science-fiction movies and cartoons. In reality, radioactive materials can look and feel just like other scrap. Items containing radiation come in a variety of shapes and sizes, ranging from old gauges and dials to specialty cameras to radio equipment. That makes the proper screening essential. Even a tiny piece of radioactive scrap can spell disaster if it gets processed with other metals and releases radiation into the environment.
Most radioactive sources that turn up in scrapyards are "orphan sources"—equipment once licensed for use in medical, scientific, and manufacturing devices. Though the owner of each device is supposed to register it with government agencies, these agencies often lose track of devices due to company shutdowns or sales, natural disasters, or poor recordkeeping. Then the building containing the device gets demolished, and the metal-shielded device ends up headed to a scrapyard.
If a scrapyard doesn't detect and properly remove such a device, its processing equipment might crack the metal shielding, exposing the yard and its workers to harmful—even deadly—radiation. If the device makes it through the yard unprocessed and undetected and ends up at a scrap consuming facility, it could end up in the melt, contaminating the entire mill and all its products, down to the furnace dust and slag. To date, steelmaking plants around the world have experienced more than 100 radiation accidents, says Steve Steranka, CEO of RadComm Systems (Oakville, Ontario). In recent years the annual incident rate has been trending upward, from about two incidents a year in the 1990s to an average of four or five a year since 2004.
If the potential health and financial implications of such incidents were not worrisome enough, radiation detection now has become a matter of national security. Since the terrorist attacks of Sept. 11, 2001, concerns have grown about the possibility of terrorists bringing radioactive materials into a country for nefarious purposes. As of March 2006, U.S. ports had installed more than 700 radiation portal monitors, among other detection equipment, according to an October 2006 article in Instrument Business Outlook. And the 2006 SAFE Port Act mandates the screening of all incoming containers at 22 U.S. ports (covering 98 percent of incoming container traffic) by the end of 2007, the article notes. Other countries are rapidly installing radiation detection systems at their ports as well.
These new detectors inevitably will affect scrap shippers. "The more radiation detectors that are put up, the more radiation is going to be detected," points out Bill Huckabee, director of sales for Ludlum Measurements (Sweetwater, Texas). A scrap shipment stopped at a port or a consuming facility due to radioactive material concerns can severely damage an operation's bottom line, Huckabee notes, and as radiation screening has become more pervasive and sophisticated, the number of rejected containers has increased. Scrap exporters are responding by modernizing their radiation detection systems to ensure they exceed the detection capability of the systems where they are sending their materials. More and better radiation detection equipment, as well as worker training, are helping them keep their yards safe and productive.
The Latest Technology
Since they first hit the market in the 1980s, radiation detection systems have advanced significantly. One of the biggest innovations is improved sensitivity. Though large radioactive sources are easy to identify, low-level sources are much more difficult to detect. To address this problem, manufacturers have improved the sensitivity of their systems, in part by using high-speed microcomputers, improved interfaces, and advanced statistical algorithms.
"Advanced background/alarm algorithms increase the signal-to-noise ratios that are critical when detecting small, heavily buried radioactive sources," Steranka explains. "More advanced systems provide extremely high detection capabilities for the types of radiation that have caused the steel industry tens of millions of dollars in cleanup costs."
The newer detectors are scintillator units made of polyvinyl toluene, a plastic material that is durable and which manufacturers can mold to any desired shape and size, Huckabee says. Manufacturers also are making larger and larger scintillators, which increases the overall sensitivity. "Bigger is better in the world of radiation detection," Huckabee says. "The larger your detector is, the better chance you have of radiation hitting the target."
Steel mills and most scrapyards are "almost exclusively" purchasing large-volume plastic scintillator-based portal or gate monitors, confirms Ray Turner, quality manager and radiation safety officer of River Metals Recycling (Fort Mitchell, Ky.). These computer-based systems are "constantly evaluating background radiation levels and adjusting themselves to compensate for background radiation," he says.
Another innovation is remote system controls, which allow detailed and accurate reporting of alarms from remote locations through virtual private networks, giving the manufacturer access to the systems for monitoring, testing, servicing, and calibration. This helps with one potential problem of modern detection systems: Their greater sensitivity can lead to frequent false alarms. "Sensitivity levels have improved drastically and now require skilled personnel to interpret the results, particularly alarm conditions," Steranka says.
"In the past … the scale operator, who had never received formal training on radiation detection systems and radioactivity in general, [was left] to interpret system operational information and alarm conditions," he notes. But interpretation of the results by a trained technician is critical, he says, "because a system's sensitivity and/or operational parameters can be accidently changed, thereby compromising the overall system operation." Steranka envisions further development in remote monitoring and control of radiation detection systems in the future, with total integration and remote factory support via special electronics and network software.
Beyond Portal Detection
Though Turner cites estimates that plastic scintillator portal monitors find more than 90 percent of detected radioactive materials, the equipment has some limitations. The same shielding that allows the safe use of a radioactive material-containing device, such as a radiation therapy device, can also make it more difficult for stationary radiation detectors to detect it. "The gauges can be so heavily buried that the emitted radiation can be completely shielded from a radiation detection system," Steranka says. "When you have a shielded gauge in a moving vehicle, and your radiation detection system is a relatively long distance away from the material being scanned—together with the fact that the wall of the vehicle adds to the shielding—there is no way the gauge will be detected." In other words, scrapyards that rely solely on having a system at the gate to check truckloads or railcar loads coming in may miss a low-activity source arriving in a very dense load, Huckabee points out. And if the source is in the middle of a load, he says, "it's beyond the laws of physics to detect it."
The most important conditions for monitoring radioactivity in scrap, Steranka says, are slow and long detection periods for the material passing in front of the detector, low scrap densities, close proximity to the material being scanned, and continual analysis of the measured background radiation levels. To monitor scrap in smaller quantities that are closer to the detection equipment, some scrapyards are supplementing their rail and truck portal detectors with magnet-, grapple-, and conveyor-mounted detectors. These technologies "will significantly increase the opportunity to catch a low-level, small radioactive source that could be missed by a vehicle radiation detection system," Steranka says. Huckabee agrees that having radiation detection equipment in multiple locations, including on conveyors and in position to check outgoing loads, is a worthwhile safety measure.
New Training Tools
Detection equipment may be the first line of defense against radioactive scrap, but training is equally important. Scrapyard owners and managers must commit to proper training to protect their employees and resources. The failure to do so can lead to devastating consequences. "Radioactive material poses a threat to human health and the environment. Exposure to radioactive material can cause severe injury, long-term health problems, and, in some cases, death," points out Doug Kramer, president of Kramer Metals (Los Angeles) and chair of ReMA's radiation task force.
Beyond the human costs, the financial costs of a leak could range from, at the low end, the return freight costs of a shipment rejected by a steel mill or foundry, up to hundreds of thousands of dollars in decontamination costs for a scrapyard that shears or shreds a device, Turner says. If a mill ends up melting a source, he adds, the average cost for decontamination is $12 million to $14 million, not counting the loss of production and business while the mill is closed.
In today's economy, scrap processing facilities can't afford to be cut off from customers or have their material held by customs or delayed by freight companies because of radioactive content. Turner says he has not heard reports of foreign ports rejecting U.S. scrap due to radiation, but if it were to happen, the costs could be significant. Other potential liabilities associated with a radiation incident include loss of consumer confidence, regulatory scrutiny, and possible fines from local, state, or federal agencies if the incident is mishandled.
To help company leaders educate themselves about radiation issues and train their workers on what to look for, ReMA's radiation task force has created a protocol for radiation safety programs. ReMA is working with a special committee of the Conference of Radiation Control Program Directors (Frankfort, Ky.) to ensure the protocol addresses all legal and regulatory requirements as well as all recommended best practices. Turner presented a sneak preview of the new protocol in St. Louis during the November 2008 ReMA Safety and Environmental Council meeting.
The underlying goal of the radiation task force, Kramer says, is to educate all members so they employ the appropriate level of radiation detection, identification, and isolation. "ISRI has training materials for members' employees—from the largest and most sophisticated operations to the smallest mom-and-pop type yard—including posters, videos, flashcards, and a radiation program guidance document that should be released this year," he says.
ISRI has geared most of the training materials toward visual identification of potential radioactive sources. The rationale is that if detectors fail to detect a device, the scrapyard workers must know what to look for: the shapes, symbols, attachments, and markings that might indicate a piece of scrap contains a radioactive source. But another aspect of training is knowing what to do once a yard detects a potential source. In the past, when a scrapyard identified a radioactive source, it might have simply told the seller to take its scrap somewhere else, without reporting it to the authorities. "Nowadays, companies are handling things differently—thanks to people like Ray Turner, who have made it easier for scrap facilities to report and handle radiation detection," Steranka says. "Putting a vehicle on the road or rail knowing that it contains radioactive material and not reporting it is a serious offense—and not worth the risk."
River Metals Recycling is serious about radiation safety, Turner says. "We have never had an accident," he says, but "we have had some very serious incidents with incoming scrap shipments. Fortunately, our extensive training paid off, and each incident has been handled properly, by the regulations, and by the book, without the release of radiation into the environment."
Kramer Metals' experience has been the same. The company has never had an accident, though it has recovered several sources over the years. "We have long placed safety above profit, so keeping our people educated and safe has been part of our business culture for a long time," Kramer says.
On the Horizon
Customer requirements, new laws and regulations, and events involving the release of radiation all can drive the design of new radiation detection systems, the manufacturers say. Steranka believes tomorrow's radiation detection systems will monitor new locations and use current technology with modified algorithms "focused on vastly improved ambient background suppression techniques and more specific attention to the specific types of radiation that have caused the most serious accidents at smelting facilities." He also predicts that advancements in the detection material will provide better energy distinction and give users more detailed information as to what radioactive source the equipment has detected—all of which should make it easier for scrapyards to identify, isolate, and control these sources before they can cause harm. •
Chelan David is a writer based in Seattle.
Radiation in scrap is a growing concern due to the proliferation of orphan sources and more screening at ports. New technologies—along with the proper training—can help keep scrapyards and their workers safe.