Nuclear Fuel Pellet Inspection via Shadow Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing automated inspection systems for nuclear fuel pellets struggle to reliably detect defects such as surface losses and protrusions on the end faces, particularly in the chamfer and dishing areas, due to complex illumination conditions and difficulty in differentiating between defects and non-defects.
Innovation Solution
An inspection system that uses a supporting device to align fuel pellets with a reference axis and an optical measuring device emitting a light beam perpendicular to the pellet axis, analyzing the shadow generated by the pellet to measure geometrical parameters and detect defects on the end and lateral faces, allowing for efficient and reliable detection of surface losses and protrusions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an image-capturing device is used to inspect end faces of fuel pellets, then the inspection can be performed during conveying, but the detection reliability in chamfer and dishing areas deteriorates due to complex illumination conditions
Solution Approach 1:
The patent replaces the image-capturing device (optical imaging system) with a shadow-based optical measuring device. Instead of capturing images and analyzing them computationally, the system uses a light source to create shadows of the pellet features on a detector, converting the inspection problem from image processing to geometric shadow analysis. This substitution eliminates illumination sensitivity issues while maintaining high-speed inspection capability
Solution Approach 2:
The patent changes the fundamental measurement parameter from image intensity and color (in image-based systems) to shadow geometry and light blockage patterns. By measuring the positional coordinates of shadow edges rather than analyzing pixel intensities, the system achieves illumination-independent defect detection while preserving high throughput inspection
2Device complexity
If the optical axis is coaxial with the pellet axis for inspection, then the setup is simple, but the ability to detect defects in recessed areas deteriorates
Solution Approach 1:
The patent deliberately positions the light source and detector asymmetrically relative to the pellet axis, with the optical axis offset from the pellet axis. This asymmetric configuration allows the light beam to illuminate the end face at an angle that reveals the geometry of recessed areas (chamfer and dishing) in the shadow projection, improving defect detection precision without significantly increasing system complexity
3Extent of automation
If conventional conveying systems are used to transport pellets during inspection, then automation is maintained, but the illumination conditions for defect detection deteriorate
Solution Approach 1:
The patent separates the conveying function from the measurement function. The conveying system transports pellets through the inspection zone, while a dedicated shadow-based optical measuring device performs measurements independently of the conveying mechanics. This segmentation allows the measurement system to use optimal lighting geometry without being constrained by the conveying system's illumination limitations
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
The system enables accurate detection and classification of defects on nuclear fuel pellets, improving the reliability of fuel pellet-cladding interaction and enhancing the inspection throughput to ten pellets per second.
Implementation Method 1
each fuel pellet interrupts the light beam and generates a shadow projected on the light detector
Data Source
AI summary
An inspection system for inspecting nuclear fuel pellets comprises a supporting device for supporting the fuel pellet(s) such that the pellet axis of each fuel pellet coincides with a reference axis, and an optical measuring device arranged for optically measuring the fuel pellet(s), the optical measuring device comprising a light emitter configured for emitting a light beam propagating along an optical axis and a light detector arranged for receiving the light beam. The fuel pellet interrupts the light beam and generates a shadow projected on the light detector. The optical measuring device includes a measuring module configured for analyzing the shadow for detecting possible defects on the end faces and/or the lateral face of each fuel pellet.