Advanced visual inspections by drone for restricted airspaces

This article aims to show the experience and results obtained in the application of drones (Remotely Piloted Autonomous Systems or RPAS) in inspection services, as an alternative to traditional tools and methods. The use of drones is especially interesting in applications with areas to be controlled that are difficult to access or restricted spaces for inspectors: systems located at heights, over large water surfaces, areas of limited permanence (aggressive atmospheres, confined spaces, high radiation, etc. ).

The chosen experience has been a DEMO on a visual inspection required by one of the aging management programs of the Almaraz Nuclear Power Plant (external surfaces located in the reservoir of the essential services cooling system). Before, it was necessary to have a boat to transport the inspectors, since the inspected system (sprinklers and lines that reach them) is located in the middle of an extensive sheet of water.

The prior preparation of this type of inspection, when it comes to flying over restricted or prohibited outdoor airspaces in critical facilities, is very laborious and requires a diligent work team. For this, great professionals have been counted on, present an agile communication between the different departments involved (Legal, Quality, Inspection, Logistics, Commercial, etc.), and leave perfectly established the roadmap necessary to implement the service on a regular basis, optimizing the process with the best guarantees of safety, quality and competitiveness.

Among the previous procedures, there are different authorizations that must be requested from different organizations (Ministry of the Interior, AESA, etc.) and companies (manufacturers) well in advance, in order to fly over a vertical flight strip of the area to be inspected. In addition, there are the usual access procedures for personnel and equipment, as well as an exhaustive security study, risk analysis, permits for Physical Security, Radiological Protection, control room, etc.

Already involved in the inspection, counting on the most experienced and disturbed pilots to work under extreme and changing conditions, the aim is to validate the inspection methodology by means of a drone with broad security guarantees. With temperatures close to 40ºC and a changing wind of 5-10 m/s, together with a flotation system mounted on the landing gear that guarantees its permanence over water in case of emergency (greater work to maintain the stability of the RPAS and therefore both less autonomy of each set of batteries), the inspection demonstration was a complete success.

The robustness and stability of the equipment must be highlighted, it requires an impressive image quality despite keeping the drone at distances greater than 8 meters from components and inspection lines that prevent compromising safety in the event of any emergency. The evolution area of ​​the drone was maintained according to the pre-approved flight plan, limited by GPS positioning coordinates, making it virtually impossible to pilot the drone outside the authorized area. However, there is a safety study that includes the calculation of the force exerted on the sprinkler system in the event that the drone “turns off” during flight and could fall from great unforeseen heights under its own weight (do deliberate damage in the hypothetical case of being able to intervene the coded team).

In addition, in systems that must be unloaded in the shortest time possible to be inspected, a significant reduction in time is achieved with the drone compared to other methods (preparation/takeoff/imaging/landing/easily agile collection).

The Client’s expectations were fully met, clearing up any concerns regarding security and wanting more. To take off again!

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