Radiation Detection by Mark Henricks

—View a list of manufacturers at the bottom of the page

Customer returns due to radiation contamination are one of the largest business risks for scrap metal recyclers. Not only is there the financial cost of reverse shipping charges, but the recycler risks damaging its reputation.

Scrap yards contain more radiation detection equipment than ever, as recyclers work to ensure greater product quality and better service to steel mill customers. Another factor is the increased volume of Eastern European scrap metal exports. These often have higher levels of contamination due to lax regulations.

Methods of radiation detection change slowly, with most advancement occurring through increasing sensitivity and portability and improving data integration. Manufacturers strive for multilayered scanning so more metal is exposed to detection while maintaining efficiency.

Radiation detectors work at three key points of the scrap recycling process. Not all recyclers maintain the full complement, but it’s clear that the greater the number of chances to inspect, the greater the chances of catching radiation before contamination of the recycling site, shipping conveyance or steel mill. Fixed systems stand sentry at yard entrances where trucks slow for weighing. Detection equipment then scans trucks from sides or overhead. Depending on configuration, scrap can be scanned 1,500 to 3,000 cubic inches at a time, up to 4,500 cubic inches with the addition of an overhead detector.

In this first line of defense, scrap is densely packed within trucks or sealed beyond the scanner’s full reach. For a more thorough once-over, recyclers use fixed system detectors with conveyor belts or within handling equipment such as grapples, charge buckets, front-end loaders and off-gas and dust systems. By the time scrap reaches this stage, material is in smaller pieces and radiation-contaminated scrap buried deep in a load might be on the surface.

“If you miss it in the truck, you’ll probably see it in the grapple or moving up on a conveyor,” says Mel Sauve, vice president of sales and marketing at Radcomm Systems Corp. in Mississauga, Ontario. Hand-held devices finish the process by permitting up-close scrutiny at random or in the event of an alarm set off during another part of the scanning process.

Some products employ new technology such as wireless and satellite communications, giving recyclers an option to transferring data by modem, Internet or Ethernet. “The ability to network all radiation detection systems into one data base facilitates management’s ability to ensure compliance to alarm procedures and provides traceability and accountability,” says Sauve, whose company now offers wireless in its large-scale and hand-held products.

S.E. International, Inc., in Summerton, Tennessee, is another manufacturer to add wireless features to its line of small hand-held survey instruments and multichannel spectrum surface and air contamination analyzers. “Detection principles have not changed much,” says Corey Walker, the company’s director of marketing, “so it is using external technologies to advance us in the market.”

The company’s units feed directly to cell phones, personal display assistants (PDAs) and handheld computers for easy monitoring. “Wireless makes it easier to transfer data without making handwritten records,” Walker says. “You don’t have to download the data or manually calculate readings from various locations.”

How well-equipped a scrap metal recycling operation is depends on what the business can afford. Prices range widely. Since the industry competes less on new patented techniques, price is often what differentiates one vendor from another. S.E. International’s survey instruments go from $289 to $685 while Thermo Electron Corp. charges $800 to $1,500 for hand-held identifiers and $20,000 to $100,000 for its ASM vehicle monitoring systems. Multichannel analyzers begin at about $4,000 and can run as high as $20,000. Software and upgrades may be extra.

Ease of use also counts. Walker says the company specializes in lightweight instruments that run on one nine-volt battery instead of four D cell batteries. “You can wear it on your waist or stick it in your pocket,” she says.

In addition to convenience, machines will get better at determining when radiation is normal background emissions occurring naturally in the environment and not a harmful isotope that needs to be managed. That will be important to curing some of what some in the industry consider overzealous management of naturally occurring radiation that may unnecessarily keep some metal scrap out of the recycling stream.

Maximizing the sensitivity of large-scale machines using special plastic or other inert crystal scintillator materials will continue to increase sensitivity and eliminate the need for time-consuming hand-held scanning to confirm an alarm was not triggered by a manmade isotope, says Gary Wascovich, product sales support manager at Thermo Electron Corp. in Waltham, Massachusetts, one of the largest radiation detection manufacturers. “The technology to identify radiation as being NORM [naturally occurring radiation material] will be used more in the future in this industry,” Wascovich says. “That’s going to be a big help.”