EHS Spotlight: Radiation Revisited

Jan 30, 2019, 15:50 PM
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January/February 2019

By Amanda Abrams

tong_feature_final3_jan_feb_2019_NEWESTThe radioactive remnants of a beer bottling plant that almost contaminated a Kentucky steel mill’s smelter in 2008. A piece of equipment formerly used for radiation therapy that was stolen and dismantled for scrap and wound up killing four in Brazil in 1987. A malfunctioning gate monitor that resulted in radioactive material being melted at a steel mill in 2004, contaminating the entire facility and costing millions of dollars in remediation. 

Scrapyard employees have heard these and other stories that make it clear: Radioactive sources in scrap material can have potentially far-reaching consequences. Although the risks to human health are likely small—unless, as in Brazil, you handle radioactive material with your bare hands, ingest it, or bring it into your home—the financial and public relations impacts can be substantial. That’s why about 30 years ago, North American metal recycling facilities started equipping their yards with radiation monitors. 

Today, one radiation detection manufacturer estimates that nearly three-quarters of all scrapyards have radiation monitors at their entrances. But simply equipping the truck scale area with a detector might not be enough, safety and radiation professionals say. For better results, analyze your equipment and procedures for blind spots, beef up education and training, and remain abreast of changes in the material stream that could affect your detection results.

Scrapyards are most likely to encounter “orphan sources”: manufactured items that have been disposed of improperly. These include radium dials, gauges, or compasses from World War II–era aircraft, vehicles, and ships; medical or industrial equipment containing cobalt-60, cesium-137, or other long-lived isotopes; and smoke detectors, which can contain americium-241. “That’s the brunt of it, 99 percent,” says John Anderson Sr., founder of Atlantic Nuclear Corp. (Rockland, Mass.), which sells detection equipment from Ludlum Measurements (Sweetwater, Texas). “Normally, nothing too serious” to human health, but of great concern to steel mills.

Those sources are slowly decreasing in number in the United States, but there are still many thousands of them around the world that haven’t yet been identified. They have the potential to enter this country as scrap, particularly when metals prices are high. While they might seem innocuous to the naked eye and could be sealed, fully encasing the radioactive material, they still must be detected and properly managed. If the shielding has been broken, the risk of contamination is greater, as is the degree of concern. 

Background radiation, naturally occurring radioactive material, and technologically enhanced NORM also cause headaches for scrapyards. Background radiation is the existing radiation in the environment, which varies across the country and around the world. Radiation detection instruments get calibrated to use the background radiation level at a particular location as their base. This can be an issue when selling scrap to a mill in an area that has a lower level of background radiation than your source of the scrap. NORM is naturally occurring radioactive material in its undis-turbed state; TENORM is NORM that has been concentrated, altered, or exposed by human activity—for example, scale clinging to pipes or drill tubing. NORM levels tend to be higher underground, which means scrap from fracking or mining operations is a likely source of this problem. 

Detection and response basics
What kind of radiation detection system makes the most sense for your yard? It depends on your size and operations. Small scrapyards might only need a single gate detector; larger operations that sell metal directly to steel mills—which themselves have extremely sophisticated and sensitive radiation-detection systems—will likely want to invest in something more complex. 

Not that a gate detector that can cost $100,000 is simple. As the first line of defense in keeping radioactive material out of a scrapyard, you need to set it at a level that is sensitive enough to pick up any radiation above background levels, but not so sensitive that it’s constantly giving false positives. Different manufacturers use different algorithms; some recommend setting the monitor at 10 percent above the background radiation level, which could be 5 microrems per hour. Others use different formulas, but the number should be similar. 

Shielding, time, and distance all affect a radiation detector’s effectiveness. Gate monitors detect gamma rays coming off of a radioactive source, but other scrap metal that surrounds a radioactive source in a load, as well as the source’s own shielding and the metal sides of the truck, can shield the radiation emissions. To increase their chances of successful detection, some scrapyards have additional detectors that operate above and below the vehicle. “The more detectors you have, the more opportunities you have to see it,” says David Wagger, ISRI’s chief scientist and director of environmental management. 

The time factor with a gate detector is the speed at which the truck passes through it—the slower the better. It’s difficult for a monitor to pick up on anything significant unless a truck is moving slower than five miles an hour, these sources say. As for distance, the closer you can position the detectors to the trucks, the better the chance they’ll have of catching the radiation. 

If the monitor’s alarm goes off, these experts suggest running the truck through the detector again. “You back the truck off and bring it through three times; if you get two alarms out of three, you isolate the truck,” says Ray Turner, president of Ray Turner Nuclear Consulting Services (Hamilton, Ohio). Turner may be the nation’s foremost authority on radiation in scrap. After isolating the truck, the designated responder should use a hand-held radiation monitor to survey the load and get a better sense of how much radiation is present and where it’s located. “You investigate every alarm,” Turner says. 

Every alarm, unless it’s clearly a false positive, also warrants a call to the state environmental health department. Depending on the size and seriousness of the source, the department may send representatives to the site. When the source is coming from a commercial supplier, most yards will reject the load and direct the driver to take it back—which they must do using a special Department of Transportation permit. If the source came from a retail customer, yards often choose to take responsibility for its management themselves, usually together with state officials. 

More stringent controls
Even if you have the most high-tech gate detector, your facility might have blind spots where radioactive material could enter. If scrap arrives or departs in rail cars, have detectors by the railroad spur—ideally, with panels on the sides as well as above and below the cars to get a comprehensive look at the load. If retail or nonferrous customers bypass the truck scale to unload at a smaller, indoor scale, that needs detection as well. 

Some scrapyards also monitor scrap-processing areas as a second line of defense in case a well-shielded ra-dioactive source slips past the gate monitor. Steve Steranka, founder of RadComm Systems (Oakville, Ontario), which makes radiation detectors, says he’s a fan of installing them in grapples. Grapple detectors have several advantages, he says: “You’re handling the scrap multiple times. [The grapple] picks it up, holds it for at least 20 seconds; the longer you get to look at it, the better it is. And ambient background radiation is almost nonexistent because you’re in the center of all this dense scrap,” he says. Detectors for magnet attachments are another option.
A senior employee at a large Midwestern scrap company says his company prefers detectors on the conveyors leaving the shredders. “The best chance to catch [radiation] is immediately after it’s been shredded,” he says. “The detectors are tied into a system that will stop the belt, and the team can respond with a hand-held [detector].” 

Of course, a conveyor-belt detector has to be installed properly—over the conveyor rather than under it because the belt’s steel can act as a shield. And the timing has to be right: The belts are moving at roughly 100 feet per minute, so by the time the detector receives a signal and the belt stops, the material will be a dozen or more feet down the conveyor. His staff has been trained where to look, this recycler says. 
As a final safeguard, send your processed scrap loads through the gate detector on the way out, particularly if you don’t have detectors in processing areas. Once you’ve processed the scrap, radioactive sources that formerly were shielded are much more likely to trip an alarm. 

Detector maintenance
You’re diligent about inspecting and maintaining your expensive scrap-processing equipment, but what about your radiation detection system? “A lot of [systems] are installed at scrap-processing facilities but then left on their own without any attention, just sitting there, maybe for 10 or more years,” Steranka says.

That monitor is changing every day. Inside its case is scintillation material that detects gamma energy from ra-dioactive sources, and that material ages over time—particularly in climates that have wide swings in temperature. The aging begins as soon as the detector is made, and it can lose the ability to detect low-energy gamma rays from isotopes like americium-241 after as few as eight years. 

That’s why radiation detectors require testing on a regular basis. Some yards do it every single day to ensure the monitor is still working well and maintaining sensitivity. “Use the same check source”—which most manufacturers will supply—“every day, and test the system in the same spot,” Turner says. To be comprehensive, he adds, “check it in at least three different locations: top, center, and bottom.” When the monitor no longer responds effectively, it’s time to replace the scintillating material.

Manufacturers also can come and calibrate the radiation monitor on an annual basis, and many can also make adjustments via a network connection on newer systems. Recertify your hand-held detectors annually as well—you’ll likely need to send them to the manufacturer or a technician to do so. 

Perhaps most important, use the monitor as it’s intended. Anderson remembers one operation where the workers became frustrated with the gate monitor. “They were getting false alarms, so they unplugged it,” he says. “Man-agement didn’t know; they thought it was all going well.” Unsurprisingly, radioactive material entered the yard without detection and eventually made its way to a steel mill, where it wound up causing extensive contamination. 

Training and experience
That anecdote illustrates one of the most important elements of radiation safety: worker experience and training. Bill Cook, the human resources, safety, and environment manager at Skagit River Steel and Recycling (Burlington, Wash.), refers to his scalemaster as his “second line of defense” after the gate detector. “He’s been there 23 years, he knows what to look for,” Cook says. “He can magically look at a load and tell [when suppliers have] hidden something in there.”

Experienced scale operators and EHS managers should know the suspicious shapes of radioactive gauges. They should understand that a gate detector might pick up the low-energy gamma radiation coming off of an isotope like americium-241/Be, which is used in oil exploration; tools that measure level, thickness, and flow; and to calibrate neutron-detection instruments. Even if hand-held detectors—most of which use sodium iodide, a different technology than portal detectors—might not register anything, the gate machine is revealing the presence of something poten-tially dangerous. With experience, these professionals also will understand that an unevenly loaded truck or rail car can cause a false positive, and that dirt could be the source of NORM that’s causing the alarm to sound. 

Luckily, there’s a close second to experience: training. Scrap industry training on how to deal with radioactive sources could be better, these sources say. The high turnover in some scrap operations is one source of the problem. “We may spend a day training people, but within a year, 50 percent [of them] are gone,” says Gary Wascovich, a market development manager for Thermo Fisher Scientific (Waltham, Mass.), a company that develops radiation detectors and other analytical instruments.  “Two years later, another 50 percent are gone, and only 25 percent of the trained people are still there.”

Repetition is one solution: daylong training for new employees and annual refresher courses for those who work in the scale house or on the response team. Teach them how to identify something that could be radioactive, how to use and maintain various detectors, what their signals mean, and what a proper response is. Then conduct drills to practice source identification and response.

Brush up on the regulations covering NORM and TENORM in your state, suggests Javid Kelley, a certified health physicist with Perma-Fix Environmental Services (Atlanta). They’re often quite complex, and they vary from state to state. And get to know your state regulator. Building even a small relationship there “makes it easy to call and say, ‘Here’s what we’ve found, here’s what we’re dealing with, what do you think?’” he says. “Then it’s not a totally cold call.”

ISRI offers some useful training resources, including a set of flashcards to help employees recognize potential radioactive sources, and more are on the way. A new ISRI radiation safety task force began meeting a couple of years ago; it first developed a new policy position, and now it’s hammering out a set of recommended best management practices. At the same time, Tony Smith, ISRI’s safety outreach manager, is partnering with the Conference of Ra-diation Control Program Directors to develop an updated radiation safety video that ISRI plans to release this summer.

Emerging concerns
Ongoing training is important because the radiation environment is continually evolving. Around 2012, European steelmakers began detecting high levels of americium-241 in their slag. The isotope may have been there for years, but workers began looking more closely and found increasing problems. In Finland, for example, one of Europe’s biggest steel plants experienced four contamination incidents in just the second half of 2018. 

The result is that European steel mills are beefing up their radiation detection systems, testing incoming scrap loads using additional technology—specifically, neutron detectors in addition to the gamma detectors—to more efficiently detect the neutrons generated from americium-241, Wascovich explains. That’s one of the harder isotopes to detect, particularly in monitors with scintillating material that has aged even a little bit. If scrap with that type of radiation finds its way to North American scrapyards, the industry will need to be ready to respond. 

Amanda Abrams is a freelance writer based in Durham, N.C.
Gate scanners are the first line of detection for radiation in scrap metal, but are they enough? Review your facility’s equipment, processes, and training to ensure you’re screening adequately and prepared to respond. 
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