How do you clean the hardened crud at the bottom of one of the most caustic and radioactive enclosures imaginable? And remember, that's after you first have to fit through a pipe with a mere 12-inch diameter to do it.

The Salt Mantis opens and closes like a pair of scissors. Closed, it fits the narrow entrance pipes to nuclear storage tanks at the Hanford site in Washington.

This was the challenge that faced CH2M Hill, located in Englewood, Colo., the company contracted by the Department of Energy to clean up the leaking nuclear waste tanks at the Hanford site in Washington State. After removing more than a half-million gallons of liquid and sludge from one of the tanks, the company discovered that there were still 300,000 gallons of salt hardened at the bottom. To break it up, a cleanup crew needed something that could shoot high-pressure water and move across the surface, after fitting through that pipe.

The answer they came up with is something they call the Salt Mantis. "Like a children's transformer, this thing morphs from something that will fit down a 15-foot, 12-inch pipe," said Rick Raymond, CH2M Hill's director of supplemental treatment. "Once at the bottom, it reconfigures itself and can crawl around the tank, find this hard salt cake, and break it up."

The Salt Mantis folds and unfolds like a pair of scissors. At the ends of one length are two hydraulically driven wheels, and at one end of the other is a sapphire nozzle that fires water at 35,000 pounds per square inch.

Open, as seen in this frame from an on-site video, the device scours hardened radioactive waste from a tank floor.

The gem is just one of many unique materials used to survive the hostile atmosphere. "Most synthetics and silicones get damaged by radiation," Raymond said. "They get very brittle, like hard glue that's been dried out." The company used a synthetic rubber called EDPM for non-metallic parts.

To keep the water spray from destroying the tank walls, there is a steel, fingered plate that extends five inches from the nozzle. Operators also have a rule prohibiting the Salt Mantis from staying in any one spot for more than 20 minutes.

CH2M Hill put the Salt Mantis into its first tank thinking it would just be a trial run and that the device wouldn't last more than 80 hours. Instead it was still going after 160 hours.

"It broke up 100 percent of the salt," Raymond said. "And we were just hoping it would prove it worked."

If you make something and it breaks down, that's bad for business. A customer doesn't want to hear that the water was too hard.

Chromalox Inc., a Pittsburgh manufacturer of electric industrial heaters, says companies that make machinery for hot water and steam processes face particular problems along this line. The original equipment maker can't control the quality of the water that a customer will use, and if the water is too hard, a scale of calcium carbonate can collect on heating elements and act as an insulator where nobody wants one. Not only can process liquid fail to heat up to full temperature, but the elements also can overheat and fail altogether.

The CaGuard works with a control system to keep tabs on scale buildup in various hot-fluid systems.

To protect the equipment, the company has developed a sensor to detect scale buildup in hot-water, steam, and even hot-oil systems. Chromalox calls the device CaGuard and says it is designed to attract scale and duplicate conditions of other submerged components. The signal from the sensor indicates scale thickness. The controller can be set to notify an operator, initiate a cleaning, or shut down a system, depending on the signal it receives. In addition, because the sensor detects the absence of liquid, it acts as a backup indicator to reduce the possibility of dry starts.

According to Kathleen Posteraro, product manager for components and process heaters, Chromalox is looking for a beta site to test CaGuard in a hot-oil system.

The probe is 3/8 inch in diameter and has a 24-inch Teflon-protected lead with an epoxy end seal. The sensor operates on 24 V dc and 120 V ac. Chromalox has four models that list for $112.50 each. The company also makes test samples available and offers discounts on orders of 25 pieces or more.

The sensor is designed to work with a broad range of controllers from off-the-shelf systems to custom platforms. The company is recommending them for use in foodservice and heavy industry, and in applications from steam tables to lube oil systems and cooling towers. The company says that using the sensor can save time and money for operators and also can reduce an OEM's warranty costs.

On Earth, oil makes an excellent lubricant. Off Earth, where gravity no longer plays its convenient circulatory role, the tried and true fluid is less than ideal. In an effort to stop using the stuff in a refrigeration compressor on the International Space Station, Lockheed Martin approached Mainstream Engineering in Rockledge, Fla.

The company's engineers replaced the compressor's old bearings with self-lubricating ones made of Vespel and impregnated with Teflon.

"As the material wears, you get fine particles that actually lubricate the bearings," said Greg Cole, Mainstream's engineering director. These bearings are grooved to dispose of the particles and avoid buildup. They also use permanently lubricated seal bearings and add a cylinder liner to the piston cylinder arrangement.

As the wear of the bearings is what produces the solid lubricant, the new compressor has a life of 1,500 hours, an order of magnitude shorter than its terrestrial, oil-lubricated peers. Mainstream Engineering hopes that the next version of the compressor will keep working for as long as 8,000 hours.

One of the main challenges of the project was finding a material that could survive long-term contact with the refrigerant, which is contained in the compressor itself, and it took several prototypes before designers settled on Vespel and Teflon. Another hurdle was fitting the new parts into the established configuration.

The first version of the oil-less compressor now sits attached to a centrifuge on the space station. It's been tested to make sure it works, but has not yet been used for any experiments.

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