A pair of autonomous RadPiper robots developed by Carnegie Mellon University’s Robotics Institute will help decommission a former US Department of Energy (DOE) nuclear facility. The RadPiper robot can safely go where humans can’t and accurately measure radiation levels on the inside of pipes.
The Portsmouth Gaseous Diffusion Plant in Piketon, Ohio, which shut down in 2000, has 10.6 million square feet of floor space. It is DOE’s largest facility under roof, with three large buildings containing enrichment process equipment that span the size of 158 football fields, including more than 75 miles of process pipe throughout the three buildings.
Finding the uranium deposits, which is necessary before the DOE decontaminates, decommissions and demolishes the facility, is a herculean task. In the first process building, human crews over the past three years performed more than 1.4 million measurements of process piping and components manually. They are close to declaring the building “cold and dark.”
“With more than 15 miles of piping to be characterized in the next process building, there is a need to seek a smarter method,” said Rodrigo V. Rimando, Jr., director of technology development for DOE’s Office of Environmental Management. “We anticipate a labor savings on the order of an eight-to-one ratio for the piping accomplished by RadPiper.”
How RadPiper Works
RadPiper will initially operate in pipes measuring 30 inches and 42 inches in diameter and will characterize radiation levels in foot-long segments of pipe. Those segments with potentially hazardous amounts of uranium-235 will be removed and decontaminated. The vast majority of the plant’s piping will remain in place and will be demolished safely along with the rest of the facility.
The tetherless robot moves through the pipe atop a pair of flexible tracks. Though the pipe is in straight sections, the autonomous robot is equipped with LIDAR and a fisheye camera to detect obstructions. RadPiper’s disc-collimated sensing instrument uses a standard sodium iodide sensor to count gamma rays.
The sensor is positioned between two large lead discs. The lead discs block gamma rays from uranium deposits that lie beyond the one-foot section of pipe that is being characterized at any given time. Whittaker said CMU is seeking a patent on the instrument.
After completing a run of pipe, RadPiper automatically returns to its launch point. Integrated data analysis and report generation frees nuclear analysts from time-consuming calculations and makes reports available the same day.
But even with RadPiper, nuclear deposits will still need to be manually identified in some cases. Still, RadPiper significantly reduces hazards to workers who otherwise must perform external measurements by hand. “This will transform the way measurements of uranium deposits are made from now on,” said William Whittaker, robotics professor and director of the Field Robotics Center.
RadPiper Could Help Cut Costs
The DOE paid CMU $1.4 million to develop the RadPiper robots. DOE officials estimate RadPiper could save tens of millions of dollars in completing the characterization of uranium deposits at the Piketon plant, and save perhaps $50 million at a similar uranium enrichment plant in Paducah, Kentucky.
CMU and Whittaker have extensive experience with robots in nuclear facilities. They designed robots to help with the cleanup of the damaged Three Mile Island reactor building in Pennsylvania and the crippled Chernobyl reactor in Ukraine.
Robots could be useful elsewhere in DOE’s defense nuclear cleanup program, which is not even half complete, Rimando said. Other sites where robots might be used are the Savannah River Site in Aiken, South Carolina, and the Hanford Site in Richland, Washington.
“With at least 50 more years of nuclear cleanup to be performed, the Robotics Institute could serve as a major pipeline of roboticists for DOE’s next several workforce generations,” he added.