Management at the Dept. of Energy’s Savannah River Site wanted to remove the radioactive waste from two 750,000-gallon holding tanks, including material which had hardened and bonded to the tanks themselves. To reduce some of the safety risks, they commissioned a robot for the job from TMR Assoc. LLC, Lakewood, Colo. The result is an 8-ft, 800-lb cleaning machine dubbed the Sand Mantis. The robot collapses into a long straight configuration which lets it feed into openings atop tanks. It uses a water jet shot through a sapphire nozzle to erode away most of the waste, which the jet also grinds into smaller particles that get removed with the water. So far, the Mantis is on track to complete the job by March of this year, three years ahead of a federal deadline.