Some of these steel tanks containing depleted uranium date back to 1951Ńand critics say their corrosion could lead to an environmental disaster. According to a DOE study, one cylinder released 110 pounds of uranium before anyone detected it.

The DOE is storing almost 5,000 aging barrels of depleted uranium in Oak Ridge, waiting for somebody to buy them. Critics say itŐll never happen.

by Joe Tarr

It is a cloudy day, and the sparkling-white minivan drives past several long warehouse-like buildings, its tires splashing in puddles on the pavement through this largely abandoned landscape of warehouses. Most of the buildings seem empty, a few sealed off because of a radioactive hazard. There are chain-link fences all around, and gates staffed by guards who diligently check the identification and clearance of all who approach.

There are large yellow signs warning of radioactivity tacked to everything. That could be an exaggeration, the thing a visitor notices most on a first trip to the Department of Energy's K-25 site at Oak Ridge. It is a place that once turned uranium into something that could generate electricity for a city—or blow one up.

The van drives to a field of 12-foot-long steel cylinders, stacked two-high in long, tight rows. Numbering in the thousands, some are coated with white paint, others decorated only with brown rust. Inside the storage yard, the tour guide walks over the cracked concrete to just a few feet from these barrels and says that if you listen closely, you can hear them "sing."

Inside, depleted uranium is jumping back and forth from solid to gas, popping faintly against its steel cage.

"You can stand next to one of these things for a year, but it's not going to affect you," assures Mark Musolf, a spokesman for Bechtel Jacobs Company, which manages the K-25 site (now called the East Tennessee Technology Park) for DOE.

The government has some 50,000 cylinders of the volatile uranium hexafluoride, including 4,683 that are being kept at Oak Ridge. DOE officials admit it would be best to convert it into a more stable substance. They want to wait, however, until there are commercial uses for it—thus offsetting conversion costs that could climb to $8 billion.

Many people, fearing calamities ranging from deadly gases escaping into the air to heavy metals poisoning drinking water, criticize that idea.

"Every day they sit there, they are an increasing environmental risk," says Ralph Hutchison, the coordinator of the Oak Ridge Environmental Peace Alliance. "There is no market out there, and they have no actual use. The Department of Energy is just saying, 'Wouldn't it be handy if someday somebody buys these from us?'"

Uranium found in nature must be broken down before it can be used in nuclear power plants or bombs. So it is turned into a gas and put through a process that separates usable uranium from the less potent uranium.

The by-product is not considered a waste by the Department of Energy, because it still contains a slight amount of the usable uranium, though it would be expensive to extract it.

Since the 1950s the United States has been taking the leftover uranium and putting it in vacuum-sealed steel tanks and stacking them in three storage yards. At Paducah, Ky., there are almost 30,000 of them, each weighing 10 to 14 tons. Another 13,000 cylinders are at Piketon, Ohio, and the rest are at Oak Ridge. Although Oak Ridge has the fewest cylinders, they are some of the oldest, dating back to 1951.

Many of the cylinders' wooden supports have rotted away, leading DOT to replace them with cement ones. Two cylinders that corroded through and were patched sit underneath makeshift wooden shelters, to keep them dry.

When the tanks are moved, they are done so with Wagner logging rigs, which have large claws built for maneuvering tree trunks. Moving the tanks is done as little as possible, since it puts the cylinders at risk for punctures or cracks. (Some cylinders can't be moved, because they've become too fragile after years of rust and corrosion, Hutchison says.)

Depleted uranium is radioactive, but it's not particularly dangerous to be around, says Janet Cash, a Bechtel Jacobs engineer.

The real danger comes when the cylinders it's kept in break down. There are different ways this can happen: One scenario is the rupturing of a cylinder, during which the uranium hexaflouride reacts with moisture in the air to form hydrofluoric acid, a highly toxic gas.

This happened Jan. 4, 1986, at a Sequoyah Fuels Corporation plant in Gore, Okla., while workers were heating a cylinder in order to remove the uranium hexafluoride inside. The gas killed one worker and injured others, and a poisonous gas cloud was blown almost a mile from the plant.

Another gruesome and longer-lasting calamity could occur if the steel cylinders corrode through the bottom and the uranium (which, being a heavy metal, is toxic to humans) contaminates ground water.

The Department of Energy eventually wants to convert the uranium hexafluoride to a more stable form, says Charles E. Bradley Jr., who oversees the depleted uranium for DOE. But the department hopes to first interest private business in buying the substance.

There are many possible uses, Bradley says.

Although it is itself radioactive, the depleted uranium could be used in shields guarding against more potent radioactive sources, he says. "You could accomplish the same level of shielding as normal concrete with far less bulk," he says.

The metal form of uranium can be used as counterweights and supports in industrial machinery. "You'd use an alloy of uranium metal in an application where you'd want the same strength and durability of steel but needed a denser material," he says.

If the uranium were used this way, care would have to be taken to ensure that people are protected from its slight radioactivity by coating it with stainless steel or surrounding it by metal parts, Bradley says. The department is planning an industry conference this June to sell companies on depleted uranium.

It's all a pipe dream, says Eugene Hoffman, a former DOE metallurgist.

"I don't think anyone has denied there are some potential uses, but only in very little amounts," says Hoffman. "Most people have determined there is very little use for this material. Own up to the fact."

Hoffman worked for DOE for 24 years. He was part of the team of DOE workers that studied the maintenance of the uranium barrels in 1992. Their extensive study is cited in other reports, but DOE has kept it as a "draft" document, leaving its recommendations unacted on.

Since he retired in 1996, Hoffman has devoted much of his time to challenging DOE over the barrels. In the basement of his home off Northshore Drive, Hoffman has accumulated a small library of reports, news articles, and other documents on uranium. The several-hundred-page draft of DOE's Environmental Impact Statement on the barrels arrived last Christmas Eve—Hoffman thought it was the best present he could get and spent the holiday poring through it.

By no means anti-nuke, Hoffman says the government made many stupid decisions over the years. He worries what will happen as the steel cylinders continue to rust and corrode.

"If you've got a steel car with no paint, sitting out in the yard for 45 years, anyone will tell you you're going to be able to sweep it up with a broom," he says.

Stacking the barrels and putting them so close together was a mistake, because it makes inspecting them too difficult, he says. The cylinders range in thickness from .625 to .313 inches thick; they must be at least .25 inch thick in order to be transported.

But several have corroded to less than that, Hoffman says.

When pinprick-sized rust holes develop, the depleted uranium reacts with the atmosphere to form several different compounds. One of these effectively plugs the hole. But other compounds formed from the breach begin to attack the steel, increasing the breach by about an inch in diameter each year. One cylinder corroded for about 13 years, releasing 110 pounds of depleted uranium into its surroundings before anyone detected it, according to the DOE study Hoffman worked on in 1992.

Although DOE does annual inspections, these scenarios can be difficult to detect due to the way the cylinders are stacked, Hoffman says.

One of Hoffman's worries is that a natural catastrophe may happen near the cylinders. The Paducah plant in Kentucky sits on the New Madrid fault line, which recorded perhaps the most violent earthquake in the United States in 1811. Scientists have reported that the fault line is at risk for a major earthquake.

The Department of Defense's safety record with cylinders has been remarkably good. Bush says that only seven of the tanks have ever broken—four of them at Oak Ridge.

"You have to realize that's a lot of steel to eat through. You would have to have some sort of damage for it to breach. It can happen with corrosion, but typically it happens when you have some sort of damage, like a crack in the wall," says Cash, the Bechtel Jacobs engineer.

Bradley says that the cylinders can be kept as they are indefinitely, as long as the country is willing to spend the money. "If corrosion is the only issue, you can keep the Golden Gate Bridge up as long as you're willing to paint it," he says. "It's a question of when people want to do something else instead."

Hoffman wants DOE to convert the depleted uranium to U3O8, its safest and most stable form. The longer the country waits, he says, the more difficult the cylinders will be to handle. Meanwhile, the enrichment plants at Paducah and Piketon are producing more than 2,000 cylinders of the stuff each year.

Hoffman points to France as a model for how the depleted uranium should be handled. That country converts all its depleted uranium to U3O8 and stores it in 3-cubic-meter metal containers, which are then stacked in sheds designed to withstand earthquakes.

"If a hundred years from now we decide there's a use for it, it's available. In the meantime, it's protected and the environment is protected," Hoffman says.

Unfortunately, it's an expensive venture. But, Hoffman says, it's time to pay the price.

"The cost of doing the inevitable goes up more every day," he points out. "The problem and the solution are pretty obvious. Mostly money is the problem."