Despite being a source of clean energy, nuclear power plants host many infrastructure components which emit a certain level of radiation in the industrial campus and its surrounding environment. The vast piping system at a plant happens to be one of the largest sources of radiation. So, the pipe network requires frequent monitoring and inspection as the power plant ages. The design for replacement of this network is mostly focused on reduced radiation and contamination exposure to personnel, equipment and the surrounding environment.
A Pressurized Water Reactor (PWR), in which the primary coolant is water, is a closed system of pipes and other components that pumps radioactive water and steam under high pressure to the reactor’s core, where it is heated by the energy released by the fission of atoms. The heated water then flows through the pipes to a steam generator, thermal energy transfers to a secondary system where steam is generated and flows to turbines which, in turn, spin electric generators.
Due to the critical nature of these pipelines, the US Nuclear Regulatory Commission inspects the pipe network of such power plants for potential corrosion that may occur inside a pipe from trapped gases. The gas particles are prone to rise to their highest points in such environments, which can lead to a disaster or a breakdown of the plant.
The technicians of PWR plant were concerned about the corrosion of pipelines and wanted to validate the measurement of several pipe runs. Advanced scanned images from 3D laser equipment enabled identification of highpoints in the entire pipe network, as well as validate correct schematic drawings with built data. Highpoints help alleviate gas trapped through installation of vents.
Traditionally, manual hand tools have been used to determine these highpoints, exposing personnel to high levels of radiation. Foreseeing the risk of traditional surveying through tape, ladders and scaffolding, R. Brooks Associates tasked Exact Metrology technicians to utilize 3D and CT scanning for pipeline inspections. The technicians used Leica HDS scanners for accurate measurements and validation of schematic drawings with built structures.
Equipped with full radiation protection suits, Exact Metrology personnel began the surveying assignment inside the plant. They scanned 20 rooms using Leica HDS scanners, which are capable of capturing 360o 3D point cloud data in approximately three minutes. The reduced duration for data capture was possible due to the automated data acquisition feature in the device that allowed the metrologists to secure themselves in low-dose radiation areas at the plant as the device continued to capture critical data.
Advanced algorithms in the software used by the technicians to assess the 3D CAD model generated by the device helped extract pipe sizes, centrelines and positions. These dimensions were collected even for those portions of pipelines that were only partially scanned. This completely alleviated the need for re-entries in the plant (which is denied once the plant is up and running), a common problem faced during manual measurements. Highly-dense point cloud data went on to help expose areas of crystallization, which are crucial in identification of leaks in pipelines. Elevation descriptors marked across pipelines procured from computer generated 3D CAD models were used by engineers to determine installation zones for vents to negate highpoints.
As per the onsite project manager and application engineer of Exact Metrology, the data captured and test results were considered acceptable by facility engineers at the power plant who went on to take corrective actions for identified problems. Another accomplishment of the project was associated with health physics. The radiation dose levels of the crew involved in the inspection were significantly lower than ALARA goals, as defined in Title 10, Section 20.1003 of the Code of Federal Regulations (10 CFR 20.1003) by the US Nuclear Regulatory Commission.
|Client||R. Brooks Associates|
|Technology partner||Leica Geosystems|
|Digital technologies||BIM, Digital Twin, reality capture|
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