This summer, a pair of autonomous robots developed by Carnegie Mellon University's (CMU) Robotics Institute will be driving through miles of pipes at a U.S. Department of Energy's former uranium enrichment plant to identify uranium deposits on pipe walls.
CMU is building two of the robots, called RadPiper, and will deliver the production prototype units to DOE's sprawling 3,778-acre Portsmouth Gaseous Diffusion Plant in Piketon, Ohio site in May.
Before DOE decontaminates, decommissions and demolishes any facility, finding old uranium deposits is necessary and a huge task.
RadPiper employs a new "disc-collimated" radiation sensor invented at CMU. The CMU team, led by William "Red" Whittaker, robotics professor and director of the Field Robotics Center, began working on the project last year, working closely with DOE and decommissioning contractor, Fluor-BWXT Portsmouth.
The CMU robot can measure radiation levels more accurately from inside the pipe than is possible with external methods. Most importantly, the CMU robot significantly reduces hazards to workers who would otherwise perform external measurements by hand while wearing protective gear and using lifts or scaffolding to reach elevated pipes.
The Portsmouth plant began operations in 1954 and produced enriched uranium, including weapons-grade uranium. Closed since 2000, the plant is DOE's largest facility under one roof, with 10.6 million square feet of floor space, comprised of three large buildings containing enrichment process equipment that span the size of 158 football fields. The process buildings contain more than 75 miles of process pipe.
In the first process building, human crews have spent three years performing more than 1.4 million measurements of process piping and components manually.
"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."
RadPiper will operate initially in pipes measuring 30 inches and 42 inches in diameter and will characterize radiation levels in each foot-long segment of pipe.
The tetherless robot moves through the pipe at a steady pace 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 ahead, such as closed valves.
The robot'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.
Pipe segments with potentially hazardous amounts of uranium-235, the fissile isotope of uranium used in nuclear reactors and weapons, 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.
After completing a run of pipe, the robot 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.
DOE has paid CMU $1.4 million to develop the robots as part of what CMU calls the Pipe Crawling Activity Measurement System. The robots could be used at 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," Whittaker said.