Helically Polarized Magnet Linear Positioning for Nuclear Reactors
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Solution Overview
Problem
Existing linear positioning systems fail to provide accurate and reliable high-resolution position measurements in extreme environmental conditions, such as high temperatures and pressures, encountered in nuclear reactors, where previous sensors are inadequate due to limited design constraints and operational longevity.
Innovation Solution
A helically polarized magnet system with a multi-axis magnetometer configuration, utilizing a plurality of north and south poles circumferentially patterned along a linear axis, coupled with a sensor array of magnetometers and sensing coils, which detects magnetic flux variations to determine precise linear position, even in harsh environments, and employs a common electrical bus and passive filters to minimize wiring and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional position sensors are used in nuclear reactors, then the system can operate in extreme environmental conditions, but the measurement precision and reliability are insufficient
Solution Approach 1:
The patent replaces traditional mechanical position sensors with a magnetic field-based detection system. A helically polarized magnet is attached to the control rod, and its position is determined by measuring the magnetic flux pattern using magnetometers, eliminating the need for mechanical contact sensors that fail in extreme nuclear reactor conditions.
Solution Approach 2:
The patent changes the measurement parameter from mechanical displacement to magnetic flux pattern detection. By utilizing the unique helical magnetic flux pattern generated by the specially polarized magnet, the system achieves high-resolution position measurement through magnetic field parameter changes rather than mechanical parameter changes.
2Duration of action of stationary object
If sensors are designed to operate in extreme temperatures and pressures, then the operational longevity improves, but the measurement precision deteriorates
Solution Approach 1:
The patent replaces mechanical sensors with a magnetic field-based system that has no moving parts and is inherently resistant to extreme temperatures and pressures. The magnet and magnetometers can operate in the harsh nuclear reactor environment for the required 60-year design life while maintaining measurement precision through magnetic field detection rather than mechanical measurement.
3Measurement precision
If high-resolution position measurement is achieved, then the position control accuracy improves, but the device complexity increases
Solution Approach 1:
The patent segments the magnetic field detection into multiple measurement points along the control rod stroke. By placing magnetometers at different positions and detecting the helical magnetic flux pattern at each point, the system achieves high-resolution position measurement through spatial segmentation of the magnetic field detection.
Solution Approach 2:
The patent adds a temporal dimension to the position measurement by utilizing the time-varying magnetic flux pattern as the magnet moves. The helical polarization creates a characteristic flux pattern that changes with position, allowing the system to determine position from the temporal evolution of the magnetic field signal.
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 provides high-resolution, high-reliability linear position sensing capable of operating in temperatures up to 350°C and pressures over 2300 psi, with single-fault tolerance and resistance to environmental variations, ensuring precise control rod positioning and extended operational life beyond 60 years.
Implementation Method 1
the magnetic flux varies at different positions along a linear path in a direction aligned with the linear axis
Implementation Method 2
A multi-axis magnetometer is configured with at least two sensing coils to detect the position of the helically polarized magnet by sensing the magnetic flux variations
Data Source
AI summary
A system includes a helically polarized magnet having a plurality of north and south poles circumferentially and helically patterned along a linear axis. Magnetic flux varies at different positions along a linear path in a direction aligned with the linear axis. A multi-axis magnetometer and/or magnetometer array is configured with at least two sensing coils to detect the position of the helically polarized magnet by sensing the magnetic flux variations at the different positions along the linear path.