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SOUND PICTURES OF STORED WASTE
Trying techniques out in a test tank with layers of debris, sludge and water that simulate conditions inside underground waste storage tanks, researchers are developing sonar technology to give DOE an image of what's going on inside tanks now being prepared for emptying.

"Acoustic Characterization should provide us with safe, easy access to the in-tank information we need," says Rich Hand, a principal engineer at DOE's Hanford, Washington Site. Ames Lab researchers are developing specialized sonar techniques to provide the Hanford team with an important inside view of the site's underground storage tanks.

It's commonplace for seeing babies in utero, fish underwater and submarines in the ocean, but now sonar technology will be giving DOE an image of the waste in some of its underground storage tanks.

"This is a quick, cost-effective method for determining what's going on inside a nuclear storage tank," says Ames Lab's David Martin. His research team is developing and field-testing monitors, similar to ultrasound or sonar transducers, to help ensure safe, effective treatment and emptying of waste from storage tanks. Getting an "inside look" is critical as DOE begins removing waste from some 250 underground tanks for safer treatment, storage and disposal.

"They need to know, for instance, the density of the waste in order to effectively design waste pumps; or where debris is, where the various layers of waste are and how well the sludge is stirred up in order to safely and effectively remove the waste," explains Amanda Clark, co-investigator on the project. Figuring out how to get this information via sonar has been a natural for Ames Lab researchers who work closely with researchers at Iowa State University's Center for Nondestructive Evaluation.

Uniquely designed to withstand the intensely radioactive and caustic in-tank environment, this monitoring technology still works like a scaled-down sonar system. Sensors send out sound waves, record the time they take to return and compute from that information the location of materials in the tank.

Collaborating with DOE's Hanford, Washington Site to meet its specific needs for tank waste information, the Ames researchers have tested monitors in two underground tanks at Hanford. The next step is to do final development testing and demonstration of the sensors during an addition of sodium hydroxide to one of the tanks.

Commercial interest is also developing. A commercial transducer maker, Airmar Technology of New Hampshire, is working closely with the scientists, producing specialized transducers for the research and expressing interest in future commercialization.

BENEFITS:

• Provides Needed Information -- Acoustic characterization can provide location of interfaces and buried objects throughout a tank, information not available with existing technologies.
• Minimizes Human Exposure -- Remote, automated technique keeps people away from contamination.
• Safe In-Tank Use -- Not likely to spark and cause combustion of gases, sonar techniques raise very little in-tank safety concern.
• Cost-Effective -- Technology cost is low for in-tank assessment capability. Costliest instrumentation is not contaminated and can be re-used.
• Quick, Easy Analysis -- Once instrumentation is in place, rapid, on-site data acquisition will be automated or run by a technician.
• Allows In-Process Monitoring -- Capable of particularly important analysis during procedures, i.e.: treatment,stirring or emptying.
• Based on Reliable Technology -- Confidence is high and techniques well-understood with established sonar technology.

BOTTOM LINE:

Safe, quick and cost-effective physical description of stored waste will help speed the decommissioning of storage tanks for newer, more effective waste treatment, storage and disposal.

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Last Modified: 1 April 2002 by dave eckels
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