This article is part of a series detailing how the Elios 3 is being used in a project by the Idaho Environmental Coalition under contract with the Department of Energy (DOE) to develop a safe method for removing several hundred cubic meters of highly radioactive waste from underground storage bins in Idaho. The name of the project is the Calcine Retrieval Project (CRP).
- The IEC under contract with the DOE needed to remove nuclear waste called calcine from a vault made in the 1950s.
- Before starting the removal, the IEC first needed to 3D map the interior of the vault to understand the environment in which the work would take place.
- After completing a detailed engineering evaluation of five possible solutions for 3D mapping the vault, the IEC determined that Flyability’s Elios 2 and Elios 3 drones were the best tools for the job.
The Challenge: 3D Mapping an Irradiated Vault
As part of the massive Idaho Cleanup Project at the Idaho National Laboratory site, the Idaho Environmental Coalition (IEC) was tasked with finding a safe way to remove 220 cubic meters (720 cubic feet) of radioactive waste stored underground over 60 years ago and moving it to a new location.
The waste, a granular material called calcine, is stored inside 6.1m (20 foot) high bins housed in a concrete vault made in the 1950s. The vaults and bins weren’t designed with the possibility of future waste removal in mind, making the task of removal all the more challenging for the IEC.
After in-depth planning and research the IEC’s CRP team (Calcine Retrieval Project) developed a novel method for removing the waste:
- Step 1: Workers drill several 25 centimeter (10 inch) diameter holes through the thick concrete roof of the vault where the storage bins are housed.
- Step 2: Workers lower 6.1 meter (20 foot) pipes called “access risers” through these holes to the top of each bin, below the roof of the vault.
- Step 3: Workers robotically weld the pipes to the top of the bin.
- Step 4: Workers robotically cut holes into the top of each bin.
- Step 5: Workers install equipment through the pipes (or access risers) that pneumatically sucks out the calcine.
The CRP’s plan for removing the calcine is ingenious. But there is actually a step 0 to this process—understanding what the interior of the vault looks like.
For the approach to work, operators would need to know of all the obstructions that might be found above the tops of the storage bins, including conduit, process piping, and structural supports. This knowledge was crucial for them to precisely locate core holes in the vault roof so that the access riser pipes would have a clear path when lowered to the bin tops.
To address this need, the CRP wanted to make a 3D model of the interior of the vault so it could accurately drill the holes and place the calcine retrieval equipment.
These 3D models could be made with LiDAR or with photogrammetry. LiDAR was the preferred option, since it could provide a greater level of detail, but whichever option worked inside the confined space would ultimately be the one selected for the job.
Evaluating Delivery Mechanisms for LiDAR and Photogrammetry Systems in a Cluttered, Confined Environment
In 2019, workers tried lowering a handheld LiDAR sensor through the only hatch in the vault roof to 3D map its interior.
Since the LiDAR sensor was limited to a single location it produced only a partial 3D map, with several “shadow areas” or blind spots (shown above right).
To create a complete 3D map of the vault’s interior, the CRP team knew it would need a delivery mechanism for either a LiDAR or photogrammetry system that could close the gaps in data that created the blind spots.
But the vault was a very-high-radiation area and confined space, presenting a challenging environment for this work.
To safely get all the data needed would require remote data collection at four different vantage points (VP1-VP4 in the image below), and there was only a single entry point for the vault (the red-dotted box in the image below), making it impossible to position a handheld LiDAR or photogrammetry system at the required locations.
To find a solution that could get them a complete 3D model, the CRP team evaluated five potential methods:
- Modifying an existing articulating arm
- Designing a new articulating arm
- Using a helium filled blimp
- Drilling multiple access holes in vault roof
- Using a commercially available inspection drone
To evaluate these possible approaches, the CRP team performed a qualitative cost and technical risk assessment that considered:
- Available CRP project data
- Technical risk
- Programmatic complexity
- Vendor input
- Project schedule
- Budget constraints
After evaluation, the CRP team determined that the option with the highest chance for technical success with acceptable estimated cost and schedule was the Elios 2, which could collect photogrammetry data by flying throughout the vault.
Note: At the time of this decision the Elios 3 was still in development. However, after the Elios 3 was subsequently finalized and launched the CRP team chose it as the tool that would be used to create the 3D model, using data collected by the LiDAR sensor that comes with it.
The CRP team provided the following reasons for choosing the Elios 2 (all of these apply to the Elios 3):
- Design. The Elios 2 is collision resilient, allowing it to maneuver and bounce around the tight spaces and piping found above the bins while remaining airborne.
- Nuclear experience. Over 80% of North American nuclear reactors use the Elios 2 for inspections. Further, Flyability’s Elios 1 had been tested in an 8 Sv/hr (800 Rad/hr) field for 10 minutes without any degradation to the drone’s capabilities, indicating that the Elios 2 would also most likely pass radiation tolerance testing.
- High quality data. The data gathered by the Elios 2 can be processed for various outputs, such as 4K-resolution visual data, long-wave thermal data, and sparse point cloud maps for localizing the collected data and creating 3D-maps of the inspected area.
- Safety. The Elios 2 can be deployed from a safe distance and operate in internal BVLOS (Beyond Visual Line of Sight) areas by using an antenna extension option, allowing the control antenna to be positioned within the area of inspection while the pilot remains in a safe location.
- Cost. The Elios 2 was relatively inexpensive compared to the other options the CRP team considered.
Testing the Elios 2
After identifying the Elios 2 as the best tool for its needs, the CRP team scheduled a test with Flyability to ensure that the drone could in fact perform the 3D mapping task.
The test was conducted at a testing site the CRP team had created just for the calcine removal effort. The site contained a full replica of the vault and bins, allowing the team to simulate the experience of flying the Elios 2 through the hatch, into the vault, and over the bins, collecting photogrammetry data for 3D mapping as it flew.
The test flight was a success, and CRP engineers concluded that the Elios 2 was a viable solution for collecting the needed 3D map data from the high-radiation, confined space within the vault.
After the test, Flyability released the next generation of its indoor drone, the Elios 3. Following the release, the CRP team determined that the Elios 3 would be an even better solution for its 3D mapping needs than the Elios 2, primarily because it is equipped with a LiDAR sensor that will allow it to create a more robust 3D model of the vault.