Elastic Wave Cavity Detection in Thick Containment Walls
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Solution Overview
Problem
Existing non-destructive evaluation methods for structural defects in nuclear power plants are inadequate for accurately detecting cavities within containment structures, which are critical for ensuring the safety and integrity of nuclear power plant containment buildings.
Innovation Solution
A method utilizing elastic wave analysis with multiple acceleration sensors and impact hammers to generate and measure three-dimensional elastic waves, applying two-dimensional distributed load and acceleration data to an inverse analysis algorithm to detect cavities within containment walls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If travel-time tomography is used for non-destructive testing, then the measurement process is simple, but the information regarding continuous material properties is limited
Solution Approach 1:
The patent transitions from traditional travel-time tomography to full waveform inversion, utilizing the complete waveform data (amplitude, phase, frequency) rather than just arrival times. This dimensional expansion of data utilization enables detailed reconstruction of continuous material properties including elastic moduli and density distributions throughout the structure.
Solution Approach 2:
The method changes the measurement parameters from simple arrival time to comprehensive waveform characteristics. By analyzing the full waveform including amplitude attenuation, phase velocity, and frequency content, the system can infer continuous material properties such as elastic moduli, density, and damping coefficients through inverse analysis.
2Measurement precision
If impact echo methods are used for non-destructive testing, then the method is effective for top-layer damage, but it cannot accurately detect cavities within thick containment walls
Solution Approach 1:
The full waveform inversion method serves multiple functions simultaneously: it can detect surface defects, subsurface cavities, and characterize bulk material properties throughout the entire structure. The method is universally applicable to various defect types and depths within containment walls, replacing the need for multiple specialized techniques.
Solution Approach 2:
The patent replaces the mechanical impact echo method with an advanced elastic wave analysis system using full waveform inversion. This substitution enables deeper penetration and more accurate cavity detection by utilizing the complete waveform information and sophisticated inverse analysis algorithms rather than simple arrival time measurements.
3Measurement precision
If multiple three-dimensional loads and acceleration sensors are used, then the cavity detection accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent divides the measurement system into multiple segments: multiple acceleration sensors positioned at different locations, multiple impact loads applied at various points, and separate processing for each sensor-load pair. This segmentation allows comprehensive coverage of the structure while enabling modular data processing and reconstruction through superposition of individual measurements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances the accuracy and reliability of non-destructive structural evaluations by identifying cavities within containment walls, improving safety and integrity assessments.
Implementation Method 1
applying multiple three-dimensional loads generating elastic waves near these acceleration sensors
Implementation Method 2
installing multiple acceleration sensors capable of measuring accelerations along three orthogonal axes within the structure
Implementation Method 3
applying the two-dimensional distributed load data and the combined acceleration data to a two-dimensional elastic wave inverse analysis algorithm
Data Source
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AI summary
The present invention relates to a method for detecting a cavity in a structure using elastic waves, the method comprising the steps in which: a plurality of acceleration sensors capable of measuring acceleration in three axial directions are installed in the structure; a plurality of three-dimensional loads having elastic waves are applied near the acceleration sensors and three-dimensional accelerations are measured by the acceleration sensors; two-dimensional distributed load data is generated by superimposing the three-dimensional loads applied for each of the plurality of acceleration sensors; superimposed acceleration data is calculated by superimposing the measured three-dimensional accelerations; and the two-dimensional distributed load data and the superimposed acceleration data are applied to a two-dimensional elastic wave inverse analysis algorithm.