Nuclear Reactor Moderator Temperature Coefficient Measurement via Signal Decomposition
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Solution Overview
Problem
Current methods for measuring moderator temperature coefficients in nuclear reactors require complex operations, are time-consuming, and struggle with noise components, especially at non-zero output power, making it difficult to obtain reliable measurements without changing the reactor's state.
Innovation Solution
A method and apparatus using singular value decomposition to process coolant temperature and reactivity signals, followed by Fourier transform to calculate auto and cross power spectral density functions, allowing for the selection and extrapolation of reliable moderator temperature coefficients without altering the reactor's state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the reactor state is changed to measure moderator temperature coefficient, then measurement can be performed, but operational complexity increases and measurement time extends
Solution Approach 1:
The patent replaces physical/mechanical changes in reactor state with signal processing methods. Instead of physically changing reactor conditions to measure the coefficient, the invention uses singular value decomposition and Fourier transform of existing operational data to extract the moderator temperature coefficient, eliminating the need for complex physical state changes.
Solution Approach 2:
The patent creates a virtual model of reactor behavior through mathematical decomposition of operational data. By decomposing coolant temperature and reactivity signals into singular value components and analyzing their spectral relationships, the system replicates the measurement process without physical state changes, obtaining the temperature coefficient from normal operational data.
2Ease of manufacture
If Fourier transform is applied directly to noise signals, then processing is simple, but measurement reliability decreases due to noise components
Solution Approach 1:
The patent segments the noisy operational signals into distinct singular value components through singular value decomposition. This decomposition separates the signal into orthogonal components with different energy levels, allowing the most significant components (which contain the relevant physical information) to be identified and processed separately from noise-dominated components.
Solution Approach 2:
The patent transforms the analysis from time domain to frequency domain through Fourier transform of the decomposed signals. This parameter transformation allows the identification of coherent frequency components that represent physical relationships between coolant temperature and reactivity, distinguishing them from random noise components in the frequency spectrum.
Data Source
AI summary
A moderator temperature coefficient measurement apparatus includes: an input section receiving plant data including a coolant temperature signal being time series data on a temperature of a coolant of a light water reactor, and a reactivity signal indicating time series data on a reactivity calculated based on a detection value of a neutron flux in the light water reactor; a singular value decomposition section decomposing the coolant temperature signal into N components T′1 (t) to T′N (t), and the reactivity signal into M components ρ′1 (t) to ρ′M (t) by a singular value decomposition method; a combination section generating a selected combination being a combination of T′i (t) selected from the N components T′1 (t) to T′N (t) and ρ′j (t) selected from the M components ρ′1 (t) to ρ′M (t); and a temperature coefficient calculation section calculating a moderator temperature coefficient based on auto and cross power spectral density functions obtained by applying a Fourier transformation to the selected combination. The moderator temperature coefficients can be detected at high precision without changing states of the plant.