While redundancy might seem like a bad idea in today's economic environment, duplicate systems in the scrap supply stream make a world of difference when it comes to monitoring radiation.
And the United States and Europe are at the top of their game in developing more-sophisticated monitoring systems that help steel mills avoid melting radioactive materials like cesium or cobalt 60.
No American steelmaker has melted a radioactive source in the past few years, in large part because of the redundancy being built into the scrap supply lines at mills and at scrapyards. The last meltdown at a domestic steel mill occurred about five years ago. This is contrast to the way things were a decade ago, when such "events"—as the U.S. Nuclear Regulatory Commission and state regulators call such incidents—happened every couple of years.
Through past experiences, mills have learned how damaging it can be to melt even a radioactive device smaller than a human hand. Cleanup and disposal cost millions of dollars on top of losing production from furnaces and other irradiated equipment.
"We attribute that reduction in incidents or events to more companies putting in more sophisticated systems," Steve Steranka, president of Rad/Comm Systems Corp., said. The Mississauga, Ontario-based equipment maker provides portal systems to monitor truck and rail deliveries, as well as charge bucket loading systems and off-gas systems that monitor the dust at baghouses.
Many of the steel and scrap industry problems with discarded radioactive sources cropped up in the 1990s. These had their genesis in the 1960s and 1970s, when radioactive devices were adapted for various uses—measuring the density of materials, for example, or the dampness in new concrete roadbeds.
The problem with radioactivity is that it has "half lives" and starts to decline after a while, Steranka said, and the original container or shield will act as a shield, thus making radiation even more difficult to detect.
Most major scrapyards, along with steel mills, have installed portal monitoring equipment at their gates, according to D.J. Schooneveld, Science Applications International Corp.'s global account manager of Exploranium radiation detection systems for the steel and scrap industries.
"Almost all of them have radiation detection systems at their gates and it is kicking down to the small yards, which are now installing detection equipment. It may not be as expensive as (the equipment used) by larger scrapyards and the steel mills, but we do see an increase in that area," he said.
Both Schooneveld and Steranka said they are urging mills and scrapyards to have multiple layers of radiation detection equipment in their facilities.
"We encourage them to put radiation equipment in the area where they do charge bucket monitoring and where they monitor the dust and the slag," Schooneveld said.
Some scrap companies have more yards and they are much further apart, Steranka said. In the past they didn't worry about those secondary, or feeder, yards because all the scrap would be shipped to the main yards, which had a portal monitoring system. But now they're putting monitoring equipment on shredder conveyor belts, and some are equipping hydraulic cranes and grapples as well. "The whole scrap industry is going through a remodeling phase, and they are adopting new policies and enforcing them at all of their facilities," he said.
Mills and scrapyards are demanding more-sophisticated systems these days. One reason is the need to minimize false alarms. A truck driver or peddler that has undergone a recent medical procedure might be the source of the radiation that sets off the alarm, not the scrap.
Also, with the consolidation in the steel and scrap industries, some companies now have multiple work sites to monitor, Steranka said. They want a networking capability so the corporate environmental manager or others charged with monitoring scrap supplies can react if a source passes through the front gates.
The technology is improving, Schooneveld said. "We are working on a new generation of radiation portals, which are providing more sensitivity and lower false alarm rates. We want to provide a greater sensitivity and provide a greater protection and lower the false alarms."
More systems are now designed for different-sized investment in the yards, Steranka said, and networking capability has grown as well.
What's lagging is wider usage of radiation monitoring equipment outside the United States and Europe, according to equipment makers. In one recent incident, an Indian company produced contaminated steel that was later used for elevator buttons. The irradiated metal wasn't discovered until the buttons were installed in elevators in France. Similarly, stainless steel coils made in a Chinese mill were found to be irradiated, but that discovery wasn't made until the coils arrived at an Italian port.
The United States and Europe are well on their way to having steel mills and most scrapyards equipped with monitoring systems, according to Steranka. Steel mills in Mexico have installed monitoring equipment, but scrapyards there are about 40 to 60 percent behind U.S. yards.
"Some steel companies and most scrapyards in other regions of the world have nothing because they think they don't have any problems," he said.