Inside Unmanned Systems

AUG-SEP 2018

Inside Unmanned Systems provides actionable business intelligence to decision-makers and influencers operating within the global UAS community. Features include analysis of key technologies, policy/regulatory developments and new product design.

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AIR HAZARD TRACKING 50   August/September 2018 unmanned systems inside DRONES AND EPRI EPRI sees the value in using drones for a variety of applications in nuclear facilities, including radiation monitoring and detection as well as asset inspection. hazmat suits and walk into potentially danger- ous situations. While they can't talk about specific use cas- es, the systems are typically deployed to survey fixed points and determine if radioactivity at those points has changed, said Bob Goldstein, CEO of US Nuclear Corp. Such surveys are completed about four times a year. Customers are also interested in quantifying radioactive plumes, determining where they're coming from and where they're going. Another poten- tial use is to check for gases coming out of the stacks at these facilities. "Right now the radioactivity levels in those plumes is determined by computer simulation. There's no measurement done," Goldstein said. "You can take the drones up the stacks and physically locate the plume and evaluate the activity in the plum and which way it's going to go, which is a great advance from what they currently do. Now workers hold a detector at waist level and point it up in the sky, hoping to see the radiation in the plume. This new method is going to work better." Because there isn't a central spent fuel repository in the U.S., plants are required to store spent fuel on-site in dry cask storage con- tainers located on independent spent fuel stor- age installation (ISFSI) areas, Cinson said. The UAS AND VIBRION THE ELECTRIC POWER RESEARCH INSTITUTE (EPRI) AND CHARLOTTE UAV are working on another drone project that involves vibration imaging for indoor inspections of welds and other vibration sensitive assets. This visual based (non-contact) methodology allows for detection and assessment of component and system vibration during operation, said Tony Cinson, EPRI's senior technical leader—nuclear plant support. The principle of operation of the OptiVibe (by Allied Reliability Group) is to use high speed video to acquire data on systems/components and compare frame by frame and pixel by pixel to detect and quantify cyclic motion. The system's output is essentially a vibrogram that renders an image of the system with false coloring overlaid to signify regions of vibration detected, he said. Further analysis quantitatively results in an assessment of the frequency of vibration detected. This is similar to outfitting the component with thousands of accelerometers (one at every pixel within the image) to build a comprehensive view of the system's motion. "In relation to power plants, there are a number of pumps, valves, motors, bearings and small bore cantilevered piping systems that typically vibrate during use," he said. "This inspection methodology can provide a precursor assessment to degradation before it becomes a significant issue requiring immediate attention. For example, if a small bore piping system is vibrating at a certain location, the location can be readily identified and restraints can be installed to minimize future vibrations that could induce mechanical fatigue cracking in a socket weld." This is typically done with a tripod mounted system that's connected to a laptop. Working with Charlotte UAV, Cinson and his team were able to put the system onboard a customized UAS platform. For this to happen, the drone had to be large enough to support the payload, which includes a high speed camera, cinematography gimbal, an on board NUC computer, and wireless data transmission equipment. The cinematography gimbal provided the necessary vibration isolation from the drone operation so high-quality data could be acquired. Flying a small modular computer, it was essential that the OptiVibe acquisition program could be executed and the large data files stored locally. Wireless communication was a key functional requirement, making it possible for the data to be acquired remotely and transferred without contact. "The concept here was to develop a mobile vibration imaging platform that could remotely acquire data while either perched at a vantage point of the system, or, ideally, acquire data while in hover mode targeting the component of interest," Cinson said. "As of today, the system is fully functional to acquire data from a perched vantage point as field trials identified we still have too much motion (drift) of the UAV in hover mode. The next phase plans to address this limitation by improving balance, improving the UAV platform, and enhancing stable flight controls. This includes making the necessary modifications to enable stable flight in GPS denied environments." Photo courtesy of EPRI.

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