After the magnitude 9.0 earthquake off the coast of Honshu, Japan in 2011, the primary power and cooling systems of the Fukushima Daiichi nuclear power plant of Tokyo Electric Power Company were shut down. Three of the reactors melted within the first three days, mainly as a result of flooding by the nearly 50 meter high tidal wave created by the earthquake. In the months that followed, an estimated 600 tonnes of radioactive fuel leaked out of the storage units. The decommissioning of the reactors is expected to take 30 to 40 years.
Investigation of damaged nuclear power plants poses a particular challenge. The radiation in one of the Fukushima Daiichi reactors was recorded at 73 Sieverts, more than 7 times the lethal dose. (Ten Sieverts would kill most people within weeks.) Therefore, researchers from the GRASP Lab of the University of Pennsylvania and the Tandon School of Engineering at New York University suggest that robots do the job. An article published on the preprint server Arxiv.org describes an autonomous quadcopter intended to inspect the interior of danger spots.
Previously, autonomous security inspection machines were already being used as a popular choice among the cleanup crews. However, they are remotely remotely controlled, physically tall and heavy. Some commercially available models are 1
Airborne drones, on the other hand, are suitable for the crowded, cramped interiors of refilling reactors, which are often out of range of GPS and local wireless. They are also compact enough to squeeze into tight spaces, eg. B. Entrance bars, which may have a diameter of less than 0.3 meters.
The main goal of this work is the development of a fully autonomous system capable of inspecting damaged sites, "the researchers write. "The proposed solution opens up new opportunities for inspecting nuclear reactors and supporting the decommissioning of nuclear weapons, which is known to be a dangerous, protracted, and protracted process."
The team's solution consists of two parts: an autonomous system with government estimation Control and assignment of modules running on custom hardware and a map-based obstacle avoidance and navigation system. Their UAC – a 0.16 meter 236-gram quadcopter and Qualcomm's Snapdragon Flight System-on-Chip – uses visual inertial radiometry combined with inertial unit (IMU) and down-facing camera data Locate their location It uses an algorithm to create an environment map with a stereo front camera used for real-time obstacle avoidance and trajectory planning.
In three trials conducted in a model of a primary containment container (PCV) – an obstacle avoidance course, luminance testing and inspection – the quadrocopter has performed well, say the researchers. It was possible to detect and avoid obstacles as narrow as 0.25 meters in diameter and to maneuver themselves safely against the clutter of the model.
"We have shown the ability to simultaneously drive [mapping and planning algorithms] aboard [a drone] with limited computational power to solve a complex nuclear inspection task," the researchers wrote. "To the best of our knowledge, this is the first fully autonomous system of this size and scale that has been used to investigate the interior of a large-scale model PCV to aid decommissioning of nuclear facilities."
They leave smaller platforms with faster sensors, improved algorithms and integrated LEDs.