Los Alamos National Laboratory

Los Alamos National Laboratory

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Eco boom

Explosives such as TNT are highly toxic to produce. That’s why the Lab is designing safer, greener replacements.
December 12, 2019
A box of explosives with a wire leading to a tree shaped and colored mushroom cloud.

Explosives such as TNT are highly toxic to produce. That’s why the Lab is designing safer, greener replacements. CREDIT: Los Alamos National Laboratory


“It actually takes very mild reaction conditions to make BOM.”- David Chavez

By J. Weston Phippen

Construction on the West Virginia Ordnance Works factory began in March 1942. The factory spread across more than 8,000 acres on the east bank of the Ohio River, about six miles north of Point Pleasant, West Virginia, tucked between the pines and maples. Eight months later the factory was producing 720,000 pounds of trinitrotoluene (TNT) every day for use during World War II.

The process of making TNT uses toluene, a solvent most commonly found in paint thinners; as well as nitric acid, sulfuric acid, and oleum oil—all caustic chemicals. The combination is washed in warm water and soda ash, then cold water, leaving behind massive pools of what’s called red or pink water—a 93 percent sulfuric acid liquid that’s clear, oily, and toxic. By the time the government closed the factory, six days after dropping Fat Man over Nagasaki in August 1945, 39 of these acidic ponds remained. Remediation workers had to “flash” all the equipment with a quick burn to rid it of chemicals. Ten pipelines that carried TNT to and from various buildings were removed.

The factory was mostly forgotten . . . until 1981, when locals noticed toxic pink water seeping from a sulfur pond into a creek. The Environmental Protection Agency (EPA) listed the location as a Superfund site, and the government has worked ever since to rid the area of contamination.

A black and white photo of the West Virginia Ordnance Works factory; in the center of the picture is a tall water tower.

The West Virginia Ordnance Works factory produced TNT, which was vital to helping the Allied Forces win World War II. But the chemicals used to create the explosive have left a toxic burden. Photo: U.S. Army Corps of Engineers.

Even after advances in production safety since World War II, making TNT still leaves behind hazardous chemicals. The United States produces millions of tons of the explosive every year, not just for military uses, but also for the construction, demolition, and mining industries. On military land alone, the Army estimates 1.2 million tons of U.S. soil are contaminated from the production and use of TNT, which the EPA considers a possible carcinogen. And because TNT leaves a 2 percent chemical trace anytime it explodes, contaminated sites aren’t limited to active and shuttered processing plants. On any bombing range and anywhere artillery is fired, grenades are hurled, or a weapon using TNT is detonated, small amounts of toxic residue are left in the ground.

It’s not likely the United States’ demand for an inexpensive, dependable explosive will lessen anytime soon. So it’s no surprise that developing a safer, greener alternative to TNT has become something of a Holy Grail quest—one that Los Alamos explosives chemist David Chavez was able to complete.

Three years ago, Chavez, answering a call from the Department of Defense, set out to develop a more eco-friendly replacement for TNT. What he created contains none of the dangerous chemicals found in TNT and leaves no toxic byproducts behind. And it’s 50 percent more powerful.

Explosives history

German chemist Julius Wilbrand accidentally invented TNT in 1863. He was trying to develop a powdery yellow clothing dye, and it took another 30 years before the world realized his invention’s potential as an explosive. Then came World War I. The Germans were the first to widely use TNT, filling their armor-piercing bombs with the new material. By World War II, TNT was standard in nearly all military explosives.

The next development came around 1940, when the British created RDX, another high explosive, which packed one-and-a-half times the energy of TNT. America honed the RDX manufacturing process and was soon producing 500 tons a day to fill the weapons carried to Europe during World War II—bazookas, “dambuster” explosives, and other massive bombs dropped from planes. To this day, most military weapons around the world use an RDX and TNT combination, called Comp B. The problem is that RDX production also involves the synthesis of toxic chemicals the EPA has termed likely carcinogens.

The hammer test

This is where Chavez’s groundbreaking science comes into play. Chavez’s office occupies a squat building in a quiet corner of Los Alamos National Laboratory. And it was here, in his lab of glass beakers and flasks, that he first thought of and created BOM—bis(1,2,4-oxadiazole)bis(methylene) dinitrate. BOM meets all the requirements of a TNT replacement: it’s relatively inert, meaning it won’t blow up easily. You can drop it on the ground and it won’t detonate. And using heat, it can be converted into a liquid, then poured into any-shaped weapon, where it solidifies—a property known as being melt castable.

A gloved hand pours liquid from a glass jar.

BOM—bis(1,2,4-oxadiazole) bis(methylene) dinitrate—is twice as powerful as TNT and leaves no toxic trace. BOM is melt castable: it can be converted into a liquid, poured into any shape, and will solidify.

Most importantly, BOM has no sulfur waste-water problem. “There’s hardly any heat in the process at all. And by eliminating the heat, you avoid the degradation products, which are toxic,” Chavez says. “It actually takes very mild reaction conditions to make BOM.”

Both BOM and TNT contain carbon, oxygen, hydrogen, and nitrogen atoms. But the difference lies in BOM’s synthesis process—only four relatively easy steps. First, Chavez dissolves a chemical in a solvent, boiling the two together. He waits for the mixture to cool, filters the byproduct, and then mixes the leftovers with another solvent. This is repeated three times with different chemicals until the last step, which involves reducing the mixture’s temperature until…voila! You have a fine, white explosive powder.

The molecular difference between TNT and BOM comes from replacing two carbon atoms with nitrogen atoms. This boosts the combustion rate and makes the explosive burn cleaner. “This material has a much better oxygen balance,” Chavez says, “so its fuel is more likely to be burned completely. And anything that’s unreacted would degrade relatively easily in the environment.” The new synthesis also made the molecule denser, another factor in why it’s 50 percent more powerful than TNT. It’s melt castable, and doesn’t require any mixing with RDX to create an explosive with the same output as Comp B. BOM alone is enough.

The BOM structure, which includes O2, O, and N.

The BOM structure spelled out in powder.

Besides being more environmentally friendly and more powerful, BOM is also safer to handle. As way of demonstrating, Chavez kneels on the ground and prepares to perform what is called the hammer test.

“I think I like this hammer better,” says Chavez, as he trades a mallet for a ball-peen. “It’s smaller.” He leans forward and places less than a one-eighth of a teaspoon of BOM on a metal block.

“Cover your ears,” Chavez says.

He smacks the hammer down and… nothing. So he packs the powder a bit more densely, then places one hammer directly atop the BOM and taps it with another. The tiny explosion echoes in the lab and down the hallway. A slight trace of smoke rises. What the simple test proves is that BOM needs deliberate action to detonate—it’s very safe but still packs a lot of energy.

The hammer test is just one of many tests experimental explosives undergo at the Lab. This way, scientists have a good understanding of what they’re working with. Some of the tests involve fancy, high-tech machines. Others, like the hammer test, are much more analog: dropping a weight from various heights on an explosive or holding a barbecue lighter to a small amount of the explosive.

BOM isn’t the only green explosive being developed by Los Alamos. Laboratory scientists are also working on a more environmentally friendly high explosive for use in nuclear weapons.

But why worry about making a high explosive in a nuclear weapon environmentally friendly?

Even if a weapon is never detonated, the Lab’s mission includes ensuring the safety of the nuclear stockpile, which involves testing new and old components and updating them as necessary. That requires the production of PBX (plastic-bonded explosive) 9501 and 9502—the high-explosive materials used inside the weapons. PBX is made in large quantities at the Pantex Plant in Amarillo, Texas. Like TNT, the current PBX explosives require mixing caustic chemicals, which creates a risk to the chemical engineers producing the explosive and leaves behind toxic waste.

Los Alamos scientist Elizabeth Francois and Chavez collaborate on many projects (throughout the BOM process they were constantly bouncing ideas off one another). Chavez came to the Lab in 2003 from Harvard University, and Francois came five years later, from the University of California, Berkeley. In 2008, they both started toying with a new PBX formulation.

Most high explosives require nitration, the chemical process of introducing nitrogen into a molecule. This step almost always involves acidic chemicals. Even BOM has a nitration process; it’s just a milder form than most. But the new process Francois and Chavez developed doesn’t. It has only an oxidation process. This allowed them to consider much milder chemicals, the result being that they were able to create an explosive called diaminoazoxyfurazan (DAAF) using common ingredients, such as baking soda. It also meant the byproduct waste was nontoxic. “It’s essentially salty water,” Francois says.

An additional benefit of DAAF is that because it can be ground into smaller particle sizes, it can have increased shock sensitivity, which means it can be used in all parts of a nuclear weapon: in detonators, as a booster, and/or as the explosive, which compresses a plutonium pit.

Francois developed a plastic bonding process for DAAF so it could be shaped and pressed into pellets, which makes it safer for handling. Once Francois figured this out, PBX 9701 was born—the first new PBX developed in four decades.

Francois, Chavez, and their team are already synthesizing PBX 9701 in the tens-of-kilograms level. In a few years it could be produced at the hundreds-of-kilograms level at the Pantex Plant.

BOM could also follow this path, but its future is less certain.

In October 2019, BOM was a finalist for an R&D 100 Award—an “Oscar of Invention.” This designation could help attract some much-needed publicity. If there’s interest in developing BOM, Chavez says, “The typical lifetime of a new molecule from discovery to production tends to be 15 to 20 years because of all the testing and searching for funding to develop the molecule.”

“If we had enough money, though,” Francois points out,“we could probably do it in five years.”

A chemist in a blue lab coat works with liquid in a round beaker.

BOM can be made in four relatively easy steps. And it’s not only better for the environment, it’s also safer for the chemists (such as David Chavez, pictured) working with the molecule.

A greener future

The U.S. Army Corps of Engineers surveys the environment at the West Virginia Ordnance Works site every five years. The last review, completed in 2016, found that after 71 years, TNT still contaminated the soil at the site. At the TNT manufacturing area, now only a cement foundation, surveyors found nitroaromatic contamination in the groundwater. The steel and clay sewer lines leaving the factory floor were also still contaminated, as well as the three reservoirs that once held 30 million gallons of red wastewater.

The latest round of remediation involved replacing warning signs around the site. Two-foot-thick soil covers contaminated dirt. Depressions were leveled where polluted water had pooled. And the Army Corps continues to pump groundwater through filters to stop contamination from seeping into the water table.

All of this is expensive. Remediation at the Ordnance Works site alone has cost the government $96.3 million so far, with about $70 million more budgeted for the future. Of course, there are many more sites contaminated by TNT all over the country, including Camp Minden in Louisiana, the Apache Powder Company site in Arizona, Joliet Army Ammunition Plant in Illinois, and Bangor Naval Submarine Base in Washington.

BOM can’t change what’s already been done. But it can ensure that processing sites don’t become health risks to humans or ruin the environment. So in the future, places like the West Virginia Ordnance Works facility might not be thought of as burdens to clean, but remembered as the places that helped win the wars that kept the nation safe.