Swarmy the robot recently completed its cleanup assignment – removing the last drum-full of thick sludge from the bottom of a deeply buried storage tank at Sandia National Laboratories.
A problem was discovered with an old wastewater tank that had been buried 26 feet under the courtyard at Sandia since the late 1950s. It originally served as a drainage tank. More recently, the tank caught gray water from benign sources, like sinks and drains in the basement. Until the tank was re-moved from service, the water was tested before it went into the city sewers, and had never shown any radioactive contamination. But the tank bottom had a thin layer of old sludge on it that had tested positive for extremely small but detectable amounts of heavy metals. The tank also tested positive for non-radioactive chemicals such as arsenic and cadmium in extremely low amounts. No sludge contaminants were ever found in the water, but engineers wanted the sludge removed before the final closing of the tank.
The 47-year-old tank’s shape, depth and position made cleanup efforts difficult. Its low-oxygen, confined-space environment precluded manned entry and inspection. Dan Borneo was the facilities project manager responsible for getting the tank cleaned up. Borneo and his group looked at small robots attached to complex vacuums. The estimated cost for those systems was about $300,000 at the time, plus another $300,000 to bring it to the location and set it up. Borneo decided to look for a cheaper alternative.
“The great thing about being at Sandia,” Borneo says, “is if you can dream up a solution to something, someone at Sandia has already built one, and it’s sitting on a shelf somewhere. The key is finding the right person with it on his shelf.” Hee wrote to a few robotics engineers and asked if they had any extra robots – and he found one.
“It took a year to find the right process,” says Paul Raglin, senior manager for nuclear facilities operations. “The amount of work that got done once we found the right one is amazing.” In only a few weeks, Swarmy removed about 14 50-gallon drums of sludge from the tank.
Swarmy was controlled remotely as it first pulled a scoop through the sludge, and in the final efforts, vacuumed the sludge from the tank bottom. The end result looked like someone swept the tank clean. The sludge-free tank will be removed from operation and monitored, awaiting eventual demolition when the building it served also is decommissioned.
Robot Cleans Up Sludge
June 1, 2007