INEEL scientists hope to zap pollution with radiation

Tuesday, January 09, 2001

Post Register

IDAHO FALLS, Idaho (AP) - A little more than 10 years ago, three Idaho National Engineering and Environmental researchers were sitting around drinking cups of morning coffee and looking at photographs.

They were studying, in particular, the brilliant blue glow given off by used-up nuclear reactor fuel decaying underwater in a nearby canal. It struck them there was a tremendous amount of radiation being given off in the storage canal, which was not being put to any interesting use.

"The conversation was like 'Gosh, that's an awful lot of energy, it's a shame that it all goes to waste," said Bruce Mincher, a consulting scientist in the radiation physics department.

At the INEEL, scientists have long loved to bombard new things with radiation and study what happens. In the 1950s, it was metals and materials used to build reactors. That was followed by everything from food to pheasants. As the site's emphasis began shifting in the late 1980s to cleaning up the waste it had produced, the caffeine-induced idea that surfaced that morning made perfect sense.

Pollution was the next logical thing to zap.

"We could probably destroy hazardous chemicals with it," Mincher said. "So we began using one kind of waste to treat another."

The scientists started exposing different kinds of pollution to that radiation field by inserting experiments into a test column in the canal. They irradiated everything from pesticides to cleaning solvents to PCBs, the carcinogenic chemicals mixed in with transformer oil and radioactive waste at the INEEL.

With the right radiation dose and mix of surrounding chemicals, they found that PCBs - which are so toxic it is illegal to bury them underground - could be broken down into harmless molecules.

That was the genesis of an idea that could replace incineration - a practice the Department of Energy has used to destroy chemicals in nuclear waste for decades but has become increasingly unpopular with the public.

The department decided nine months ago to table an incinerator at the INEEL, largely designed to destroy PCBs, after residents in Jackson filed a lawsuit to stop it.

Now the department is searching for emerging technologies that might do the same job without releasing air emissions that scare neighboring residents. But cleaning up waste by subjecting it to radiation may be just as difficult for the public to embrace, even though that counterintuitive practice is beginning to be used by other countries.

The machine and the physics involved are somewhat similar to the X-ray machine at a dentist's office. It sends out a beam of electrons that produce radiation but does not cause the tooth itself to become radioactive. When aimed at certain kinds of pollution, those X-rays spark chemical reactions that break down the hazardous compounds.

Unlike incineration, the process does not significantly heat up the waste or release unhealthy air emissions. Japan has begun destroying chemicals in car fumes pouring out of traffic tunnels by exposing them to a radiation beam. Russia cleaned up a lake polluted by a rubber plant by pumping out the water and irradiating it.

"Green radiation is a well-kept secret. We're hoping to change that," Mincher said. "We just have to convince the world that X-rays are a good thing."

The researchers have already demonstrated the technology can successfully destroy PCBs in liquid transformer oil. They are working on adapting it to treat PCBs mixed in with boots, rags, equipment, debris and soil that were slated to be burned in the incinerator.

The PCBs would have to be separated from that plutonium-contaminated waste first, but INEEL researchers are investigating two other processes to accomplish that task.

For the last several years, the INEEL has been using accelerators housed at Idaho State University as its radiation source, since it would not be practical to use radiation from spent fuel in a real-world cleanup project. Those machines send electrons through a series of accelerating chambers to create energetic X-ray beams.

They can be turned on and off, so they do not pose a constant radiation hazard, Mincher said. Right now they are studying ways to improve the efficiency and reduce the time the waste has to be exposed to the radiation beam.

That reduces the amount of energy and money that needs to be spent.

"There's a real good chance this could be cheaper than incineration," Mincher said. "It's a question of how long you have to put it through the system, which translates to dollars."

So far, the technology has only been tested on a laboratory scale, meaning tiny test tubes of pollution. The next step, which would require considerably more funding, would be to build a pilot-scale facility where larger volumes of PCBs could be treated.

The Department of Energy is considering dozens of different alternatives to incineration, and a national panel has recently recommended four other technologies as the most promising solutions. But the researchers are hoping they will benefit from additional research money the panel has recommended the department spend to develop less mature, yet perhaps more efficient, alternatives.

"There are other options that are out there. This is just one solution, and there's no guarantee," said Richard Brey, a physics professor at Idaho State who has collaborated on the project. "But we think this is a good one."