Go inside a radioactive waste storage vault — with a drone, of course
Ever wonder what the inside of a radioactive waste storage vault looks like? You can go inside — via a drone, of course.
In what’s believed to be a mission that’s the first of its kind, the U.S. Department of Energy flew a drone within a high-level radioactive waste storage vault at the Idaho National Laboratory Site. The drone at hand was the Elios 3 made by Swiss-based drone-maker Flyability, which is a collision-tolerant drone equipped with a LiDAR sensor for indoor 3D mapping.
And the drone did exactly that — 3D map a vault built in the 1960s to store radioactive waste. That map will be used to provide crucial information ultimate used to plan its removal. The vault is located at the Idaho Nuclear Technology and Engineering Center at the Idaho National Laboratory Site in eastern Idaho.
The mission was conducted in conjunction with DOE contractor Idaho Environmental Coalition (IEC). IEC in 2021 was awarded a $6.4 billion, 10-year contract to manage cleanup operations.
And in one, 7-minute flight, the drone was able to get LiDAR data needed to create a robust 3D map of the vault. From there, an expert from 3D-mapping software company GeoSLAM was there to immediately process the LiDAR data on GeoSLAM’s software in real-time. Teams said the successful results were relieving, especially given the high levels of radiation in the vault.
Watch it all in action here:
Why were drones mapping radioactive waste?
The radioactive waste mapping project has been in the works for a few years now through the IEC’s Calcine Retrieval Project. The project sought to find a way to 3D map the interior of a particular waste storage vault filled with calcine. And it’s not just one vault; there are six vaults on the site storing a total of 4,400 cubic meters of calcine.
Calcine is a granulated, high-level radioactive waste that had originally been placed in 20-foot-tall stainless-steel bins stored inside the vault. It’s a dried byproduct of radioactive liquid waste that was generated during historic spent nuclear fuel reprocessing runs until 1992. And at the time, no plans had ever been made for its removal — until recently.
The IEC’s plan involved drilling into the vault, robotically welding pipes onto the tops of each bin, cutting into the bins using a plasma cutter, then using the pipes to pneumatically transfer the calcine. But first, that all required a map of the vault’s interior — which is where drones came into play.
Other potential tools under consideration to make the map included an articulating arm and a helium-filled blimp.
Ultimately though, the IEC chose the Elios 3 drone. That drone launched just last year. It relies on a SLAM engine, which is short for Simultaneous Localization and Mapping, — to explore and understand environments. The Elios 3 stands out for its FlyAware Inspector 4.0 software, which can generate 3D models. It is also notable because of its unique design that features signature cage and unique reversing motors. Flyability even says it can recover from flipping upside-down without crashing. Its also P-44 compliant design, which is a rating to show it can fly in rugged, harsh environments without concerns of water splashes or dust.
And the drone is also radiation tolerant now, to. The IEC conducted tests where it exposed the Elios 3 to up to 10,000 Roentgen per hour of radiation to ensure it would be able to operate inside the vault. The IEC even went so far as to build a life-sized replica of the vault so that its pilots could be trained in an environment that simulated the real environment in which they planned to fly.
An interesting FAA aside
Of course, while the drone did the dirty work, the job far from replaced humans. Beyond the drone operators and mapping experts, approximately 50 people were involved in the process, which included a bit of a bizarre task — a government project “skirting” government rules of sorts. One of the biggest tasks was for people to help cover the top of the vault with a plastic tent. That enabled the mission to be considered “indoors,” and made it more permissible under Federal Aviation Administration and Department of Energy (DOE) requirements, which have strict rules around flying drones in airspace (outdors), including that drones must remain within line of sight unless there is a separate waiver.
And yes, the drone did fly outside of sight given the depth of the vault. And according to the team at Flyability, “the flight into the vault was quite tense,” according to a statement from the company. “If the drone was lost, it could not be retrieved.”
Not all the missions went perfectly
While some missions were successful, not all were. Three flights were attempted, but the third was not so lucky.
Flyability said it had two successful LiDAR data collection flights. But for the third flight, which the teams are calling “experimental,” the IEC mounted a dosimeters to the drone, which is a type of device that measures dose uptake of external ionizing radiation. It also added significant weight to the drone, and — for reasons not fully understood — the drone entered the vault but not able to produce enough lift to maintain altitude.
“It made a slow descent to the top of one of the storage bins and became snagged on a piece of angle iron,” according to a statement from Flyability.
Freeing the drone did not work, and ultimately the battery died. But even the failed flight was not a complete failure. While trapped, the drone was still able to transmit a maximum radiation reading of 7 Gy/h (700 rad/h) at the top of the bin (the teams say that leaving the drone down there on top of the storage bin presents no hazards to human safety or the integrity of the bin).
So what’s next for Flyability and the DOE? The drone itself has likely done its job, but now that the vault has been 3D mapped, the next step is to plan for the removal of the calcine, a process IEC plans to begin this year.
Want to learn more about using drones to support removal of radioactive waste? The team at Flyability shared a pretty neat case study that goes in greater detail about the mission.
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