Nuclear Fuel Burn-up Profile Measurement Using Multi-Detector Signal Comparison
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Solution Overview
Problem
Existing burn-up profile measurement methods for fuel assemblies in nuclear reactors face challenges such as unreliable results due to noise and detector sensitivity changes, high failure rates, and long measurement times, particularly when using multiple detectors or moving the fuel assembly during measurement.
Innovation Solution
A method involving setting detectors at predetermined intervals along the fuel assembly's axial direction, relative movement during measurement, and determining signal soundness by comparing radiation signal distributions from multiple detectors to ensure accuracy and reliability, with redundant measurements to validate signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a large number of detectors are arranged to measure burn-up profile simultaneously, then measurement time is reduced, but reliability of measurement results deteriorates due to noise and detector sensitivity changes
Solution Approach 1:
The patent implements feedback by continuously monitoring detector signals and comparing them against reference values. When abnormal signals are detected, the system identifies and excludes these outliers from the burn-up profile calculation, thereby maintaining measurement reliability while using multiple detectors for efficient measurement.
Solution Approach 2:
The patent uses copying by measuring the same fuel assembly portion multiple times with different detectors and comparing the results. This creates redundant measurement copies that can be used to verify signal consistency and identify abnormal readings, resolving the contradiction between measurement speed and reliability.
2Measurement precision
If the fuel assembly is moved during measurement to cover entire length, then measurement completeness is improved, but measurement reliability deteriorates due to noise from motor and circuit
Solution Approach 1:
The patent extracts the harmful noise factor by separating the measurement process into discrete positional steps. At each position, multiple detectors measure the same portion independently, allowing the system to identify and exclude measurements affected by motor noise or circuit interference, thereby maintaining reliability while achieving complete length coverage.
Solution Approach 2:
The system uses feedback by comparing measurements from multiple detectors at the same position to identify abnormal readings caused by movement-related noise. This allows the fuel assembly to be moved for complete measurement while filtering out unreliable data points.
3Measurement precision
If detector sensitivity changes or noise occurs, then measurement accuracy deteriorates, but excluding abnormal values requires additional examination time
Solution Approach 1:
The patent applies preliminary action by pre-establishing reference values for detector signals before the actual measurement. During measurement, abnormal values are automatically identified by comparing against these pre-set references, enabling rapid exclusion of outliers without requiring extensive post-measurement examination, thus maintaining both accuracy and efficiency.
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 reliable and efficient measurement of burn-up profiles by reducing noise interference, lowering failure rates, and shortening measurement time while maintaining data integrity, thus improving the accuracy and efficiency of fuel assembly assessments.
Implementation Method 1
setting plural detectors, which detect radiation, in an axial direction of a fuel assembly
Data Source
AI summary
An upper detector and a lower detector that face at least one side of a fuel assembly, on which neutrons are irradiated in a nuclear reactor, and detect radiation are set at a predetermined interval in an axial direction of the fuel assembly. Distributions of radiation signals are measured by the upper detector and the lower detector while the fuel assembly and the upper detector and the lower detectors are relatively moved along the axial direction of the fuel assembly. Soundness of radiation signals measured by the upper detector and the lower detector is determined in every measurement by comparing radiation signal distributions obtained by measuring the same portion in the axial direction of the fuel assembly in a multiplexed manner with the upper detector and the lower detector. Thereafter, relative burn-up is calculated by utilizing the measured radiation signals to measure a burn-up profile. According to the present invention, it is possible to measure a burn-up profile of the fuel assembly while securing reliability of a measurement result.