Ultrasonic Probe Inspection of Reactor Pressure Vessel Welds
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Solution Overview
Problem
The challenge in inspecting weld zones within nuclear reactor pressure vessels is the complexity and narrowness of the areas, which limits accessibility and accuracy, especially when using ultrasonic testing due to the three-dimensional shape changes and poor ultrasonic propagation properties.
Innovation Solution
An inspection apparatus with a probe emitting ultrasonic waves, a probe holding unit for maintaining contact or constant distance, a pressing unit for alignment parallel to the control rod drive housing, and a rotator for 360-degree rotation, allowing for precise inspection of complex and narrow weld zones by adjusting the probe's size and position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ultrasonic testing is performed on weld zones with complex three-dimensional shapes and narrow spaces, then inspection coverage is improved, but accessibility and inspection accuracy deteriorate due to limited space and poor ultrasonic propagation
Solution Approach 1:
The patent transitions from traditional external ultrasonic inspection to internal inspection by placing the ultrasonic probe inside the reactor pressure vessel through the control rod drive housing. This dimensional change allows the probe to directly access weld zones from the interior, eliminating the limitations of external access and enabling inspection of complex three-dimensional shapes and narrow spaces that were previously inaccessible.
Solution Approach 2:
The ultrasonic probe is nested within the control rod drive housing, which itself is positioned inside the reactor pressure vessel. This nested arrangement allows the inspection apparatus to be housed within existing structural components, enabling internal inspection without requiring separate access channels or openings in the pressure vessel wall.
2Measurement precision
If the probe is positioned close to three-dimensionally shape-changing weld zones, then inspection accuracy is improved, but the complexity of adjusting probe position and maintaining contact increases
Solution Approach 1:
The probe is equipped with an automatic focusing mechanism that self-adjusts to maintain optimal contact with the weld zone surface. The system automatically tracks the three-dimensional shape changes of the weld zones and maintains proper probe positioning without manual intervention, thereby achieving high inspection accuracy while reducing the complexity of probe positioning and contact maintenance.
3Length of stationary object
If ultrasonic waves are transmitted through large weld portions with poor propagation properties, then deeper region inspection is achieved, but signal quality and detection reliability deteriorate
Solution Approach 1:
The patent employs locally adapted ultrasonic inspection techniques where the probe characteristics and inspection parameters are optimized for specific local weld zone conditions. By adjusting the ultrasonic wave parameters and probe positioning according to the local geometry and material properties of each weld zone, the system maintains high signal quality and detection reliability even when inspecting deeper regions with poor ultrasonic propagation properties.
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
Enables easy and accurate inspection of three-dimensionally shape-changing weld zones, improving accessibility and reducing difficulties in ultrasonic wave propagation, allowing for effective detection of cracks and evaluation of their depth within the reactor pressure vessel.
Implementation Method 1
a probe for emitting an ultrasonic wave
Data Source
AI summary
An object of the present invention is to provide an inspection apparatus for inspecting weld zones in a reactor pressure vessel, the inspection apparatus comprising: an ultrasonic probe 6 for emitting an ultrasonic wave; a probe holding unit 60 for holding the ultrasonic probe 6 such that a ultrasonic wave transmitting surface of the ultrasonic probe 6 is kept in direct contact with or at a constant distance from the outer surface of the reactor pressure vessel 1; a pressing unit 50 for pressing the probe holding unit 60 parallel to a central axis of a control rod drive housing 8 against the reactor pressure vessel; and a rotator 40 for rotating the probe holding unit 60 and the pressing unit 50 about the central axis of the control rod drive housing 8.