Vibration-Based Annulus Spacer Detection and Repositioning
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Solution Overview
Problem
There is a need for a method and apparatus to detect and reposition snug-fitting annulus spacers in nuclear reactors, as existing electromagnetic techniques are not applicable due to the non-welded design of these spacers, and current methods do not effectively address the challenge of maintaining optimal spacer position over the reactor's life, which can lead to operational issues and reduced reactor lifespan.
Innovation Solution
A method and apparatus that utilize vibration to detect and reposition annulus spacers by isolating a section of the inner tube, measuring vibration changes, and using piezo-actuators and accelerometers to displace the spacer longitudinally, allowing for precise positioning and adaptation to changing boundary conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If electromagnetic coil is used to reposition spacers, then loose-fitting spacers with welded girdle wire can be repositioned, but snug-fitting spacers with non-welded girdle wire cannot be repositioned
Solution Approach 1:
The patent replaces the electromagnetic actuation system with a mechanical vibration-based system. Instead of using electromagnetic coils that require continuous electrical contact, the invention uses a vibration source to generate mechanical vibrations that propagate through the pressure tube to the spacer, causing it to move along the tube without requiring electrical connectivity or direct mechanical access to the spacer.
Solution Approach 2:
The patent introduces the pressure tube as an intermediary medium to transmit vibrational energy from the vibration source to the spacer. The vibration source couples energy into the pressure tube, which then acts as a waveguide to deliver mechanical energy to the spacer at the target location, enabling indirect actuation of the spacer without direct contact or electrical connection.
2Ease of manufacture
If spacers are held by friction alone, then loose-fitting spacers can be installed, but they may move from desired position during reactor operation
Solution Approach 1:
The patent applies mechanical vibration to the pressure tube to induce motion in the spacer. By generating vibrations at appropriate frequencies and amplitudes, the spacer is caused to move along the pressure tube to the desired position. The vibration overcomes the friction holding the spacer in place, enabling precise positioning adjustment during reactor operation.
Solution Approach 2:
The patent incorporates sensors to detect the position of the spacer and provides feedback to the control system. This feedback mechanism allows the system to monitor spacer position continuously and make adjustments as needed, ensuring the spacer remains at the optimal position despite changes in friction conditions or reactor operation.
3Reliability
If spacers are not directly accessible by mechanical means, then reactor structure is maintained, but detection and repositioning becomes difficult
Solution Approach 1:
The patent replaces direct mechanical access methods with a vibration-based indirect actuation system. The vibration source can be positioned inside the reactor core and transmit vibrations through the pressure tube to the spacer, eliminating the need for direct mechanical access to the spacer while maintaining reactor structural integrity.
Solution Approach 2:
The patent uses the pressure tube as an intermediary to bridge the gap between the accessible vibration source and the inaccessible spacer. The pressure tube serves as a mechanical waveguide that transmits vibrational energy from the vibration source to the spacer, enabling detection and repositioning without direct access to the spacer.
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 effective detection and repositioning of annulus spacers, ensuring optimal radial spacing and load distribution, thereby extending reactor life and preventing operational issues such as sagging pressure tubes and improper spacer alignment.
Implementation Method 1
one or more piezo-actuators associated with said tool head and operable to vibrate said inner tube
Implementation Method 2
accelerometers associated with said tool head for measuring vibration of said inner tube
Implementation Method 3
vibrating the annulus spacer by vibrating the isolated section of the wall at a desired frequency such that the annulus spacer is displaced longitudinally
Data Source
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AI summary
Detecting and/or positioning annulus spacers, to maintain the annular space between a pressure tube within a calandria tube of a nuclear reactor, includes vibrating the tube with a transducer to induce motion of the annulus spacer, measuring vibration of the tube for a first response and a second response, computing a first frequency-domain response function for the first response and a second frequency-domain response function for the second response, and measuring a relative phase and amplitude shift between the first and second frequency-domain response functions to determine movement of the annulus spacer.