Jet Pump Vibration Monitoring via Ultrasonic Echo Analysis
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Solution Overview
Problem
Monitoring minute relative vibrations between reactor internals in a nuclear reactor pressure vessel is challenging due to temperature-induced changes in sound speed and ultrasonic wave propagation, leading to difficulties in identifying reflected echoes and measuring vibration amplitudes with high precision.
Innovation Solution
The method involves irradiating ultrasonic waves to multiple reactor internals, processing reflected waves to calculate relative vibrations based on detection time differences, and using ultrasonic reflection surfaces to transmit and receive waves, allowing for precise identification and measurement of vibrational states by accounting for sound speed changes and temperature shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If ultrasonic waves are transmitted to reactor internals to monitor vibration, then vibration detection capability is improved, but temperature-induced sound speed changes cause measurement precision to deteriorate
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the ultrasonic wave transmission frequency based on detected temperature variations. As temperature changes alter the sound speed in reactor water, the system modifies the transmission frequency to maintain accurate vibration measurements, thereby resolving the contradiction between detection capability and measurement precision under varying thermal conditions
Solution Approach 2:
The system implements feedback by continuously monitoring temperature and using this information to correct ultrasonic wave propagation time measurements. The temperature data feeds into the vibration analysis algorithm, allowing the system to compensate for sound speed variations and maintain precise vibration amplitude measurements despite thermal fluctuations
2Difficulty of detecting and measuring
If ultrasonic waves are used to detect reactor internal vibration, then vibration monitoring is enabled, but reflected echo identification becomes difficult due to temperature-induced sound speed changes
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing reference ultrasonic wave propagation characteristics at various temperature points. Before actual vibration measurement, the system uses detected temperature to select or interpolate the appropriate reference data, enabling accurate reflected echo identification without being affected by real-time sound speed variations
Solution Approach 2:
The system dynamically adjusts the expected ultrasonic wave propagation time based on temperature-induced sound speed changes. By modifying this parameter in real-time according to temperature measurements, the system maintains accurate reflected echo identification despite varying thermal conditions in the reactor
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
This approach enables the accurate monitoring of minute relative vibrations, improving the evaluation of reactor internal soundness and reducing measurement noise, allowing for the easy identification of reflected echoes and precise amplitude measurement.
Implementation Method 1
ultrasonic waves are transmitted from an ultrasonic sensor installed on an outside surface of the RPV to the jet pump via the RPV and reactor water in the RPV
Implementation Method 2
the change of propagation time of the ultrasonic waves is measured based on ultrasonic velocity of the RPV, ultrasonic velocity of the reactor water
Data Source
AI summary
Vibration of a jet pump installed in a reactor pressure vessel of a boiling water reactor is monitored. Ultrasonic waves are transmitted from an ultrasonic sensor installed on an outer surface of the reactor pressure vessel toward a throat and a diffuser of the jet pump. When the ultrasonic waves reach respective outer surfaces of the throat and diffuser, reflected waves are generated at the respective outer surfaces. The ultrasonic sensor receives those reflected waves. The ultrasonic signal process section obtains a distance in the horizontal direction between the throat and the diffuser based on a time difference of the reflected waves reflected from respective reflection surfaces of the throat and diffuser and a sound speed in reactor water in the neighborhood of the throat and diffuser. A relative vibration is obtained based on the change with time of the distance.