Neutron Flux Measurement with Dynamic Sensitivity Correction
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Solution Overview
Problem
Conventional neutron flux measurement apparatuses in nuclear reactors face accuracy issues when the reactor output changes frequently, leading to incorrect correction of detector sensitivity and reduced measurement accuracy due to emitter material consumption.
Innovation Solution
A neutron flux measurement apparatus that includes a self-powered detector, a neutron flux counting unit, a storage unit for recording neutron flux changes, and a calculation unit for correcting detector sensitivity based on recorded data, allowing for accurate neutron flux measurement even with frequent changes in nuclear reactor output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the nuclear reactor output is kept constant as base load power supply, then the detector sensitivity correction can be performed using simple attenuation calculation, but the system cannot adapt to frequent output changes and loses measurement accuracy
Solution Approach 1:
The patent applies dynamics by making the measurement interval Δt variable rather than fixed. The calculation unit dynamically adjusts the measurement interval based on the rate of change of reactor output. When output changes rapidly, the system shortens the measurement interval to capture the changing conditions, thereby maintaining measurement accuracy while adapting to varying operational states.
Solution Approach 2:
The patent implements feedback by using the measured reactor output and its rate of change to continuously adjust the measurement interval. The calculation unit monitors the output changes and feeds this information back to modify the measurement strategy, ensuring that sensitivity correction remains accurate even when operational conditions change frequently.
2Measurement precision
If the measurement interval is shortened to capture frequent output changes, then the measurement accuracy is maintained, but the measurement complexity and data processing load increase
Solution Approach 1:
The system dynamically adjusts the measurement interval based on actual reactor output changes rather than using a fixed short interval. This means measurements are taken frequently only when necessary (during rapid output changes), reducing overall data processing load while maintaining accuracy during critical periods.
Solution Approach 2:
The patent changes the parameter of measurement interval from a constant value to a variable value that depends on reactor output conditions. This parameter adaptation allows the system to optimize between measurement accuracy and processing complexity by adjusting the interval based on the actual rate of change of reactor output.
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 high-accuracy neutron flux measurement by adjusting the measurement interval and correcting detector sensitivity in real-time, reducing errors and the need for additional calibration devices, thus improving measurement precision and reducing maintenance costs.
Implementation Method 1
a material called an emitter material, which comparatively readily reacts with a neutron, such as rhodium or vanadium is used. Such materials have a high neutron capture cross-section which means the probability of reaction with a neutron, and therefore cause a dominantly large amount of radioactivation reaction through interaction with neutrons
Implementation Method 2
cause beta decay at the time of transition to a stable atom through nuclear transmutation by capturing a neutron. Here, the self-powered neutron detector having rhodium, vanadium, or the like as the emitter material outputs current based on electrons emitted by beta decay due to radioactivation of the emitter material through neutron irradiation
Data Source
AI summary
A neutron flux measurement apparatus includes: a storage which records, as record data, a measured value indicating change in a neutron flux in a nuclear reactor corresponding to adjustment control for output of the nuclear reactor during a first set period; and a calculation circuitry which, on the basis of the record data, performs correction for a detector sensitivity to a neutron of a self-powered detector at a time point in accordance with the adjustment control during a second set period after the first set period, the time point being a time point when the second set period has elapsed, and derives the neutron flux at the time point using the corrected detector sensitivity.