Crawling, autonomous robot to help decommission US nuclear facility
Image credit: Carnegie Mellon University
Two autonomous pipe-crawling robots are set to begin cleaning out a former nuclear facility in Ohio by identifying uranium deposits on the walls of pipes.
In their mission, the robots will inspect miles of pipes at the US Department of Energy (DOE)’s former uranium enrichment plant, the Portsmouth Gaseous Diffusion Plant in Piketon, Ohio. The plant produced enriched uranium from 1954 to 2013, including for nuclear weapons. It is the largest under roof facility belonging to the DOE, and contains more than 75 miles of process pipe.
Inspecting the pipes to locate uranium deposits is a challenging task; over the past three years, human operators have performed more than 1.4 million measurements on this piping manually.
“With more than 15 miles of piping to be characterised in the next process building, there is a need to seek a smarter method,” said Rodrigo V Rimando Jr, director of technology development at the DOE’s Office of Environmental Management.
“We anticipate labour savings on the order of an eight-to-one ratio for the piping accomplished by RadPiper.”
The pipe-crawling robots were developed at Carnegie Mellon University’s Robotics Institute. Researchers at the institute have demonstrated that this robot is capable of measuring radiation levels more accurately while crawling inside the pipe than it is possible to do from the outside.
The robots – which do not have to be tethered – move through pipes using flexible tracks, and use lidar and a fisheye camera to detect obstructions. They crawl through the pipes and characterise radiation levels in each foot-long segment of pipe. Segments with hazardous amounts of enriched uranium can be identified, removed, and decontaminated, while safe piping can be demolished with the rest of the facility. The robot makes use of a disc-collimated radiation sensor developed by Carnegie Mellon researchers to characterise radiation in the pipes.
The university is building two of the robots – named RadPiper – ready to deliver to the decommissioning site in May.
The researchers hope that not only will the robot save money in labour costs – tens of millions of dollars – but also reduce hazard to workers who must otherwise spend time inside the facility wearing protective gear and climbing scaffolding to reach some pipes.
If all goes well for the RadPiper robots, they could perform the same function at a similar uranium enrichment plant in Paducah, Kentucky, which is currently undergoing decommissioning. Although the robots will take on the majority of the work, some manual inspections will remain necessary in both facilities.
“This will transform the way measurements of uranium deposits are made from now on,” said Professor William Whittaker, director of the Field Robotics Center at Carnegie Mellon.
The team behind RadPiper have years of experience using robots for cleaning nuclear facilities; the Robotics Institute designed and constructed robots to help clean the Three Mile Island reactor in Pennsylvania and the Chernobyl reactor in Ukraine.