Radiation Detectors

The scrap industry was still in its technological infancy when the first commercial radiation detector—the Geiger counter, famed for its clickety-click readout—was developed more than 70 years ago.
   Back then, none but the most farsighted or paranoid scrap recycler could’ve envisioned that the deadly, invisible force of radiation could threaten his livelihood and life. But today, radiation detectors are essential tools for running a good scrap operation.
   he technology behind most radiation detectors is basically the same, notes Mike Mattia, ISRI’s director of risk management. The original Geiger counters used a gas tube to detect radiation. Though they were accurate instruments, they weren’t sensitive to subtle changes in radiation, which can be essential to discovering a radioactive source buried and shielded by a truckload of scrap metal, Mattia says.
   Much greater sensitivity is possible from modern microprocessor-controlled instruments, which use either sodium iodide crystals or plastic panels made from material such as polyvinyl toluene (PVT) to convert the disintegrating ions of radiation into electronic signals that the detectors “read.” Mattia compares the new technology to a person with poor vision who suddenly puts on a pair of glasses. “Now you can better see the disintegrations,” he explains.
   While sodium iodide crystals are considered the most sensitive medium for detecting radiation, they’re generally relegated to handheld instruments, which are commonly used to locate a radioactive source after a large gate monitor has detected radiation in a load of scrap. Those gate monitors generally use panels of PVT, which is far more cost-effective for covering a large surface area than the expensive-to-grow sodium iodide crystals, sources note.
   So if manufacturers of current detectors essentially use the same detection media, what sets their devices apart?
   For one, each uses different algorithms—the step-by-step mathematical procedures written into the software that runs modern detectors and determines when a system will sound an alarm and when it won’t. These algorithms are the manufacturer’s secret formula that makes each system different. Often, the algorithms are based on the detection experiences from actual scrap processors, gathered in some cases on a daily basis via modem transmissions between the detector and the manufacturer.
   Such electronic feedback is just one of the features and services offered by different manufacturers that distinguish their detection equipment.
   Offering an automotive analogy, Mattia observes that though all cars use an internal combustion engine, “there’s still a difference between an economy car and a luxury car based on factors like how fast the engine goes, how nice the seats are, how strong the chassis is, and how expensive the car is.”

What to Keep in Mind
While there are only about nine manufacturers of radiation detection equipment for the scrap 
industry (see “Connecting With Detectors” at right), the bells and whistles of their products can vary greatly. 
When comparing detectors, you need to consider a variety of factors, including:
   • What level of confidence do you require in the system? Steel mills and foundries, for instance, face multimillion-dollar cleanups if they melt a radioactive source. As a result, they often buy the most advanced and most expensive detection systems and often double up on protection, with detectors placed at the gates as well as at their charge buckets. Likewise, a scrap processor with an expensive shredder or large shear might invest in a more expensive detection system because his losses from processing a radioactive source are potentially much greater than a recycler who does less-extensive processing.
   • What can you spend? Handheld monitors are priced anywhere from several hundred dollars to several thousand, while gate monitors for scanning trucks or railcars range from $4,000 to $5,000 for a simple scale version to more than $80,000 for the most advanced, state-of-the-art systems like those used at steel mills and foundries. (Many manufacturers make equipment for both the low end and high end of the market, earmarking their less-expensive models for scrap processors.)
   • Is it enough just to know that something set off your radiation detector, or do you need to know exactly what kind of radioactive material it is? Certain higher-end detectors can identify the specific isotope or isotopes, drawing from a preset “library” of choices. You can even add customized isotopes to the system’s memory. And while the average device will detect the most common types of radioactive material—which usually emit gamma rays—that a scrap facility could receive, you can also purchase special equipment to catch neutrons, which are emitted by some of the deadliest radioactive material, including weapons-grade plutonium.
   • Do you trust your own truck drivers or the drivers of outside vehicles to move past the detectors slowly enough—around 5 mph—to accurately scan the vehicle? Some systems monitor each vehicle’s speed with infrared sensors and sound an alarm when the truck is moving too fast.
   • Will your employees remember what to do when the alarm sounds? Some detectors can display written instructions on how to respond and record all the information—from when the radiation was detected to what part of the truck it was detected in—in the system’s memory to be printed out for later review. You can even send the alarm transmission to a radiation safety officer or other key personnel located far from the detector, and you can send along a graphic display of the radiation levels detected.
   • Where will you place your radiation detectors? Gate monitors at the inbound scale are common, but there are also models that work (usually as a secondary detection device) on conveyors, on the boom of an excavator equipped with a magnet or grapple, and even within the grapple, either at the base plate where the tines are attached or inside the tines themselves. And do you want a wireless system?
   • How concerned are you about background radiation and the potential for false positives? Detection equipment is imperfect. A sudden fluctuation in background radiation can set off the alarms, even if the cause is something as simple as an uneven load of scrap in the truck or the gap between the truck cab and trailer, a driver who recently underwent medical radiation treatment, or industrial X-ray equipment being used even at considerable distances from the scrap facility. Certain detectors can compensate for the changes that occur as a truck passes, while others can recognize the medical or X-ray origins of the reading.

Manufacturers’ Showroom
If you’re in the market for a new or upgraded radiation detection system, what are your choices? Returning to the automotive analogy, the following profiles (in alphabetical order) offer a quick visit to the “showrooms” of leading vendors.
   Berkeley Nucleonics Corp.: This manufacturer, based in San Rafael, Calif., provides detection systems that the U.S. Department of Energy has recommended as “highly effective,” and which are well-suited to the scrap industry, notes John Yee, applications engineer. The SAM (Surveillance and Measurement) systems identify and quantify multiple isotopes in real-time. By mathematically transforming the sodium iodide-detected data and by collecting information in consecutive time slices, the SAM can fully report from a library of 95 isotopes in two seconds, Yee says. The SAM can alert the user to the dose rate and identify the nature of more than 20 of the isotopes—categorizing them as “industrial,” “medical,” or “sensitive nuclear material” (such as dangerous weapons-grade plutonium or enriched uranium). Thus, a minimally trained user can quickly tell if, for instance, the alarm detected a life-threatening hazard or simply sounded because the truck driver recently underwent a radiopharmaceutical treatment, notes Gary Mattesich, nuclear products manager. The portable 935 and its stationary twin, the 905 (good for conveyor belts, Yee notes), feature temperature stabilization to prevent data skewing throughout the day, shielding to help pinpoint sources of radiation, and a backlighted display for easier reading. Alarm thresholds can be set uniformly or on an isotope-by-isotope basis, and the systems offer optional neutron detection.
   Though the recently introduced systems are upscale handhelds—the 905 costs approximately $4,500 while the 935 is approximately $8,000—they’ve been demonstrated to metal recycling groups in Southern California and at a facility of one of the West Coast’s largest processors, Mattesich notes.
   BICRON: BICRON’s line of radiation detectors—made by the Solon, Ohio-based company whose named recently changed to Saint Gobain Crystals and Detectors—ranges from handheld instruments, including a portable multichannel analyzer for identifying isotopes, to large gate monitoring systems, notes Gary Wascovich, product specialist. Most of the BICRON gate monitoring systems use PVT, though one small system designed for monitoring material on platform scales uses sodium iodide. Likewise, its handheld units typically use scintillation detectors, though a few employ Geiger Mueller tube probes. BICRON’s strengths lie in its experience in designing monitoring systems for industrial applications, specifically, offering a variety of detector configurations matched to specific monitoring requirements, sophisticated scanning algorithm design, and expertise in detector technology, Wascovich says. He notes that the company is the world’s leading supplier of PVT-based detectors, typically used in vehicle monitoring systems, as well as inorganic detector materials such as sodium iodide and cesium iodide. The company has also designed two new systems that can be mounted on cranes in order to monitor the material being picked up by a grapple or magnet. 
   BICRON portable instruments range in price from $325 for electronic dosimeters to more than $8,000 for a multichannel analyzer, though the average price is about $1,200. The firm’s gate monitoring systems start at $4,500 for the platform scale system and can exceed $80,000, depending on the size and number of detectors. In addition, systems are available as conveyor monitors in a range of $11,000 to $17,000.
   Dansteel Engineering A/S: This Danish-owned firm, with a North American office in Chicago, features “super-ruggedized” detectors that can be tailored for almost any scrap handling equipment, notes Michael Johst, general manager for North America. The standard product line consists of detectors designed for use on a crane boom as well as inside the tines of a grapple. Dansteel’s CRD (Crane Radiation Detection) systems use sodium iodide, which allows users to dynamically adjust the alarm threshold to a point just above the natural background radiation, thus maximizing the sensitivity and avoiding false alarms caused by weather conditions, Johst explains. CRD systems such as the SM 2.2 are “especially designed for radiation detection on small and medium-sized scrap handlers,” the company notes, especially when loading or unloading trucks, railcars, or barges, or when feeding material into shredders, shears, or balers. This boom-mounted device provides much longer scanning time to a less-shielded amount of scrap, making detection more effective, Johst says.
   Likewise, the tine-mounted SM 2.2G provides even greater scanning opportunity because it places the detector against the scrap, separated only by the protective steel of the tine itself. The systems can provide a continuous log of scanning information and send e-mails to designated officials within the user’s company when an alarm sounds.
Depending on the number of detectors and how they’re arranged, Dansteel’s products range in price from an $8,000 system designed specifically for scrap processors to roughly $40,000, notes Johst.
   Eberline Instruments: Santa Fe, N.M.-based Eberline is part of ESM Eberline Instruments Strahlen- und Umweltmesstechnik GmbH (Erlangen, Germany). The company’s line of detection equipment includes handheld probes, gate monitors for trucks or railcars, and a crane-based system that employs two independent measuring devices. Eberline’s instruments work with an algorithm system called the natural background reduction (NBR) method, which continuously monitors background radiation levels, simultaneously investigates for naturally occurring radioactive material (NORM) as well as manmade radioactive sources, and adjusts for both the background and potential shielding when a vehicle passes. The system also provides a graphic display to indicate where in a load of scrap a potential radioactive source was detected.
   Eberline manufactures and supports products made by two former manufacturers: the National Nuclear and Xetex lines. The company also offers an Ethernet-based network for linking radiation detectors from various manufacturers to one or more PC workstations to provide a continuous log of scanning data as well as e-mail and pager notification of key personnel when an alarm sounds.
(Note: Information on Eberline was gathered from the company’s Web site and brochures. No one from Eberline could be reached for comment, nor was pricing information available.)
   Exploranium: This Canadian company, with its North American sales office in Knoxville, Tenn., offers scrap processors a wide variety of instruments, from handhelds through advanced gate monitors, with several designed specifically for the scrap market, notes David Page, manager of scrap recycling products.
   At the low-end of its gate monitoring systems is the GR-123, a PVT monitor designed to be installed and operated with minimal effort or expertise—almost a “plug-and-play” system—and “ideally suited for the small metal recycler,” the company says. At the opposite end of the scale is the AT-900, which caters to the largest scrap operations, Page says. This system includes detailed graphics of a vehicle passing through to isolate the location of suspect material, a menu that pops up with custom instructions (available in multiple languages) for users to follow when the alarm sounds, and hard-drive memory to record incidents. Optional features enable the detector to determine if the alarm is caused by a void in an uneven load of scrap and distinguish between a genuine alarm caused by a buried source and a “nuisance alarm” set off by something like X-ray radiography used near the facility.
   Exploranium also recently introduced the AT-140—a sodium iodide detector mounted on a crane boom—and offers a “tele-check” service on its higher-end systems that provides a weekly analysis of a detector’s performance via modem.
   Exploranium’s handheld monitors range in price from roughly $1,000 for a basic unit to nearly $8,000 for a triple-meter model that combines a dose and survey meter with a spectrometer for identifying specific isotopes. The GR-123 costs less than $20,000, while several gate monitors fall in a $20,000 to $50,000 range and the AT-900 costs approximately $60,000. In addition, the crane-mounted AT-140 is “priced for the scrap industry” at under $20,000, Page notes.
   Ludlum Measurements Inc.: Based in Sweetwater, Texas, Ludlum has been manufacturing sodium iodide handheld detectors since the early 1960s, but it only entered the PVT gate monitor market in 1998, explains Bill Huckabee, sales manager. To keep its prices affordable for scrap recyclers, Ludlum avoids adding a lot of bells and whistles to its products, he notes. For instance, the company provides users with a “check source” (a piece of radioactive material with which the user can confirm the system’s performance) rather than offering an ongoing, modem-based analysis. But Ludlum prides itself on manufacturing its own PVT—to hold down costs and ensure a quality product, Huckabee says—as well as its own photomultiplier tubes, which are an essential component for converting radiation into electronic signals. Ludlum’s microprocessor-controlled instruments maintain a floating alarm point in relation to background radiation, taking readings every tenth of a second and working in combination with photo cells to monitor a vehicle’s progress through the detector panels. This helps avoid nuisance alarms without missing actual sources, Huckabee explains.
   Ludlum’s handheld units range from $850 to $1,400, while its gate monitors for scrap processors cost from $18,000 to about $32,000, Huckabee notes, though the company also makes more expensive gate monitors for steel mills and foundries. In addition, Ludlum manufactures conveyor monitors, priced at about $3,200.
   Quantrad Corp.: This Madison, Wis., firm manufactures two handheld multichannel analyzers that can identify the location of a radioactive source in a load of scrap and determine the isotope, explains Frank Ziemba, vice president of research and development. Though these analyzers—the Scout and the Ranger—are predominantly used by state regulatory personnel to investigate radiation incidents, a scrap processor could find them useful, especially if he wants to confirm what material is in a load of scrap while waiting for the state regulator to arrive, Ziemba notes. The Ranger, in particular, is designed as an easy-to-operate, one-button device that also incorporates a second detector for identifying neutrons, Ziemba says. Both instruments are priced from $5,000 to $10,000, depending on options.
   Rad/Comm Systems Corp.: Founded in 1992 specifically for the scrap industry, this Mississauga, Ontario, firm offers a wide range of products that provide the same levels of sensitivity for detecting radiation but with different levels of “confidence” for the user, explains Steve Steranka, president. For instance, Rad/Comm makes less-expensive detectors that simply alert users with an audible alarm and flashing light when radioactivity is detected, as well as more upscale models with advanced graphic displays that store all alarm information in memory and can automatically shut down scrap processing equipment when the alarm sounds. Rad/Comm engineers can assist users in deciding which system, at which price, offers greater confidence against a radiation incident, Steranka says.
   Uniquely, Rad/Comm uses the same detecting medium—PVT—in both its gate monitors and its handheld devices, which makes its handheld detection medium larger than most portable devices, Steranka notes. However, these larger handhelds can also be plugged into a docking station to serve as an area monitor, he adds.
   Rad/Comm offers special detectors for small vehicles—such as peddler trade pickups—and conveyor belts, as well as the large PVT panel models for trucks and railcars. The company also features a wireless detection system called the Cricket that’s installed in the base plate of a grapple, allowing extended scanning times with virtually no background radiation interference, Steranka says. The Cricket, which uses a proprietary scanning medium, can also be installed on a crane boom to detect material held by a magnet. This unit essentially replaces an earlier device called the RC/5 that had to be picked up by the grapple and passed over scrap loads, Steranka adds.
   Rad/Comm’s portable monitors range in price from $1,500 to $5,500, while its gate monitors cost from $10,000 to as much as $70,000, depending on options. The Cricket is priced from $18,000 to $80,000, based on the size of the detecting material desired.
   Ronan Engineering Co.: Ronan, based in Florence, Ky., makes both radiation detection systems and the some of the very radioactive sources in its measuring devices that scrap processors strive to exclude from the scrap stream. This dual role helps Ronan make its detectors extremely sensitive, explains James Ryan, sales manager. Ronan manufactures its own detectors from PVT for gate or rail monitors. In some devices, sodium iodide or cesium iodide can be used to enhance sensitivity. The company doesn’t make handheld devices per se, though it does produce sodium iodide area monitors. In addition, Ronan makes detectors for crane and bucket monitoring. The company’s system will work on Windows-based software and offers modem-based analysis of system performance.
   Ronan’s area monitors cost about $2,000 per detector, while its crane devices are around $50,000 and its gate monitors range from $60,000 to $80,000.

Future Features
   Since many radioactive sources remain dangerous for years into the future, the detection industry will clearly be around for some time. Manufacturers see numerous trends in their products, ranging from greater user-friendliness to improved graphics, new detection media, as well as an increasingly sophisticated user base.
   The practice of adding detectors directly to grapples is expected to continue and even expand. Some firms are also working to add detectors inside magnets. And while such innovations face obstacles—such as the heat and magnetic fields of the magnet and the impact of the grapples—detector manufacturers express confidence in their efforts so far.
   Scrap recyclers can expect detectors to become more compatible with other equipment, encompassing more Windows-based software, manufacturers predict. Wireless detection systems should also become more prevalent, as well as systems that transmit data via cellular phone technology. And though some manufacturers still maintain that scrap processors just want to detect and reject, regardless of the radioactive material in question, others see a growing use of isotope-identifying technology.
   Price, of course, will ultimately determine what many scrap companies use. Looking ahead, some manufacturers see a pricing structure that moves both up and down simultaneously, providing more and more bells and whistles for users who want to pay for them, as well as effective but bare-bones models for those on a budget.
   As one manufacturer notes: “Scrap processors can get good protection and not have to spend top dollar. But if they want the same level of protection as their customers—the steel mills or foundries—then they need to invest in the same systems. There’s no getting around that.” 

Connecting With Detectors
The following nine firms manufacture radiation detection equipment used by the scrap industry.

Berkeley Nucleonics Corp.  800/234-7858 or 415/453-9955 (fax, 415/453-9956)  www.berkeleynucleonics.com

BICRON  800/472-5656 or 440/248-7400 (fax, 440/349-6581)  www.bicron.com

Dansteel Engineering A/S  773/353-2051 (fax, 773/353-2052)  www.dansteel-engineering.dk

Eberline Instruments  505/471-3232 (fax, 505/473-9221)  www.eberline.com

Exploranium  865/539-6099 (fax, 865/539-1916)  www.exploranium.com

Ludlum Measurements Inc.  800/622-0828 or 915/235-5494 (fax, 915/235-4672)  www.ludlums.com

Quantrad Corp.   608/821-0821 (fax, 608/821-0822)  www.quantrad.com

Rad/Comm Systems Corp.  800/588-5229 or 905/678-6503 (fax, 905/678-6518)  www.radcommsystems.com

Ronan Engineering Co.  859/342-8500 (fax, 859/342-6426)  www.ronanmeasure.com•