Scientists at the Robotics institute of Carnegie Mellon University have developed a new robot called RadPiper for the purpose of finding radioactive materials in the pipes of the U.S. Department of Energy (DoE) Piketon, Ohio facility. This project is part of the CMU Pipe Crawling Activity Measurement System to revolutionize the efficiency and safety of the DoE nuclear cleanup program which will take fifty years or more.
The DoE plant in Piketon spent forty-six years enriching uranium to weapons grade for our nuclear arsenal. The plant was decommissioned in 2000. The senior project scientist for the RadPiper team said, “At the time that it was operating, it was using as much electricity as Manhattan just to operate the uranium enrichment plan. There are more efficient ways to do this now. So if we needed to enrich a bunch of uranium, which hopefully we don't right now, this wouldn't be the way to do it.”
The U.S. government intends to demolish the plant and replace it with a new industrial park. However, before they can do that, they need to inspect the entire facility for radioactive materials and decontaminate it. Without this very thorough inspection and decontamination, the workers carrying out the demolition might be exposed to dangerous amounts of radiation. It is even possible that there could be an explosion if there is a great enough concentration of U-235 in one location. Every foot of pipe in the facility must be inspected. It is estimated that there are seventy-five miles of pipe in the three large buildings of the plant.
Prior to the invention of the RadPiper robot, the inspection and decontamination of an enrichment plant were done by hand. The workers used motorized scissor lifts for pipes that were up to fifteen feet in the air. Radiation readings would be taken every few feet. It was time consuming and expensive.
At Piketon over the past three years, the workers took one million four hundred thousand measurements. The results of these measurements are hand written. It may take years to analyze these measurements and the cost could exceed fifty billion dollars.
In order to expedite this process, the DoE gave CMU one million four hundred thousand dollars to develop a pair of wireless robots called RadPipers. These two robots will inspect the remain fifteen miles of pipes at Piketon which have not been inspected yet.
RadPiper contains a disc-collimated sensing instrument which utilizes an off the shelf sodium iodide sensor that counts gamma rays. The sensor is located between two big disks made of lead that are spaced a foot apart. The robot moves down the pipe one foot at a time. When it stops, the detector measures the radiation from the one-foot section of pipe between the lead disks which block radiation from other parts of the pipe. When a section of pipe is found to be contaminated, it is removed and disposed of.
The robot cannot turn corners and there are many places where the piping in the facility does turn corners. It does have a camera onboard which can alert the operators if there is an obstruction or problem in the pipe. The robot can return to its starting point automatically. The robot transmits its findings to a laptop computer which can carry out analyses of measurements in minutes or hours.
The RadPiper robot is almost finished and the developers hope to be able to begin measurements at the Piketon facility in May or June. They also intend to use the RadPiper at another closed uranium enrichment plant in Paducah, Kentucky. The senior project scientist said, “During the World War II era and the Cold War era, there was [this mindset] of we have to develop as quickly as possible, and basically they made a big mess. And now we're stuck with trying to clean it up. And I think robotics is going to be an important part of that.”
Clients in Canada and Japan would like to use the RadPiper on their nuclear cleanup projects. Other entities are interested in adapting the RadPiper robot to inspect different kinds of piping systems. A private company will spin off from CMU to handle commercial applications.
