The Effect of Gamma Rays

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Is there a 30-year-old, 2,000-pound potbellied stove sitting around your school somewhere? The government is looking for it--and its radioactive contents.


It weighs 2,000 pounds. It's alive. And the government wants to know if there's one lurking in a school near you. It's a Gammator 50, an instructional device containing radioactive cesium-137.

The federal Atomic Energy Commission donated the state-of-the-art instruments to school science programs back in the 1960s when nuclear energy seemed the wave of the future. And the classroom experiments the contraptions made possible once awed students and teachers alike.

But technology--and interest--eventually moved on, and Gammators were left collecting dust in the back of science labs and storage closets. A few were hauled away.

After 20-odd years, the Nuclear Regulatory Commission, the regulatory successor to the Atomic Energy Commission, is updating its records. Inspectors have been visiting schools in the Northeast--close to Radiation Machinery Corp., the Parsippany, N.J.-based manufacturer of the devices--to trace the whereabouts of the still highly radioactive material.

Duncan White, a senior physicist for the NRC, says because the Gammator 50 was intended for school use, its design assures complete containment of the radioactive material.

"They're designed to be inherently safe," White says. "We're simply going through these old files to make sure our records are up-to-date and the devices are in good shape and aren't leaking or damaged."

Designed to replicate the effects of gamma radiation on cells, the Gammator 50 looks like something from an old "Star Trek" episode. The black rounded cabinet resembles a pot-bellied stove on stilts. Several inches of lead surround the 400 curies (about a teacup) of cesium-137 housed in its irradiation chamber.

The classroom experiment would begin when a small turntable holding sample material--students exposed everything from potatoes to frog embryos to the isotope--was rotated to the back of the chamber, the exposure timer was set, and the motor was turned on. Students would then wait to witness the effects--both positive and negative--of radiation on their samples. Irradiated seeds, for example, would later grow into stunted plants.

Though the use of the Gammator 50 has waned over the years, the radioactive metal inside them is still pretty hot. Cesium-137--used today to treat cancer--has a half-life of 30 years, leaving only half the original isotope inside the devices while the other half decays. And if the Gammator 50 leaked or was improperly dumped, people could unknowingly be exposed to dangerous levels of radiation.

But White insists there's "nothing alarmist" in the NRC's efforts to track the devices down. "We're more concerned with radioactive material that's more portable," he says. "You'd need a forklift to move these units, and they're clearly labeled," so it would be difficult to mistakenly dump or misuse them. What's more, he adds, the few devices the agency located over the summer were in good condition and in good hands.

A Gammator 50 in Parsippany Hills High School in New Jersey has gone unused for more than a decade; the science teacher it was originally licensed to has long since retired.

"Radiation is out of the limelight," says district science superintendent Jim Simes. "We haven't used it in years. It's been locked away in the back of a storeroom."

Because the safekeeping of the unused device is ultimately his responsibility, Simes says he'd like to return the gift to the giver. But its heft, and second-floor location, make that a costly proposition--a problem officials at the NRC say they are looking into.

White says his agency's first priority is accounting for the appliances. The NRC will then coordinate the transfer of Gammators with the U.S. Department of Energy.

Vol. 16, Issue 01

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