Gamma Thermometer Calibration for Nuclear Instruments
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Solution Overview
Problem
Existing neutron monitoring systems in nuclear reactors face challenges in calibrating nuclear instruments accurately and efficiently, especially when the reactor is not in steady-state operation, as current methods are complex, costly, and lack real-time calibration capabilities.
Innovation Solution
The implementation of gamma thermometers that measure local neutron and gamma flux, allowing for the calculation of compensated signals to calibrate nuclear instruments by determining selected yield fractions and time constants of delayed gamma sources, enabling calibration even when the reactor is not in steady-state operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods are used for nuclear instruments, then calibration can be performed, but the process becomes complex and costly
Solution Approach 1:
The patent introduces a gamma thermometer as an intermediary device that measures gamma ray flux to infer neutron flux. This mediator enables calibration of nuclear instruments without requiring complex traditional calibration procedures, as the gamma thermometer provides a direct measurement path through gamma ray detection that correlates to neutron flux conditions
Solution Approach 2:
The patent replaces traditional mechanical or complex procedural calibration methods with a radiation-based measurement system. By using gamma ray detection and thermal conduction principles, the system substitutes complex calibration mechanics with a more straightforward physical measurement process that directly correlates gamma flux to neutron flux
2Measurement precision
If traditional calibration methods are used for nuclear instruments, then calibration can be performed, but real-time calibration capability is lacking
Solution Approach 1:
The patent enables continuous real-time calibration by maintaining constant operation of the gamma thermometer and associated detectors. The system continuously measures gamma ray flux and converts it to neutron flux information, providing ongoing calibration capability rather than periodic or batch calibration processes
Solution Approach 2:
The patent implements feedback mechanisms where the measured gamma ray flux is continuously converted to inferred neutron flux values, which are then used to adjust and maintain calibration of nuclear instruments. This closed-loop feedback enables real-time calibration adjustments based on actual operating conditions
3Measurement precision
If delayed gamma sources are not compensated for, then measurement is simpler, but measurement accuracy deteriorates
Solution Approach 1:
The patent segments the gamma ray signal into distinct components: prompt gamma rays and delayed gamma rays. By separating these components and applying different processing approaches to each, the system can accurately account for delayed gamma contributions without overwhelming complexity in the overall measurement process
Solution Approach 2:
The patent performs preliminary identification and characterization of delayed gamma sources before final neutron flux calculation. By pre-processing the signal to identify delayed gamma components and their characteristics, the system prepares the data in advance for accurate compensation in the final measurement, reducing complexity in the main calculation path
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 simplifies, automates, and reduces the cost of calibrating nuclear instruments by compensating for delayed gamma sources, allowing for real-time calibration and improving the accuracy of neutron flux measurements.
Implementation Method 1
measuring in the gamma thermometer local gamma flux
Implementation Method 2
measuring in the nuclear instrument local neutron flux
Implementation Method 3
calculating selected yield fractions for specific groups of delayed gamma sources; calculating time constants for the specific groups of delayed gamma sources
Data Source
AI summary
A method of calibrating a nuclear instrument using a gamma thermometer may include: measuring, in the instrument, local neutron flux; generating, from the instrument, a first signal proportional to the neutron flux; measuring, in the gamma thermometer, local gamma flux; generating, from the gamma thermometer, a second signal proportional to the gamma flux; compensating the second signal; and calibrating a gain of the instrument based on the compensated second signal. Compensating the second signal may include: calculating selected yield fractions for specific groups of delayed gamma sources; calculating time constants for the specific groups; calculating a third signal that corresponds to delayed local gamma flux based on the selected yield fractions and time constants; and calculating the compensated second signal by subtracting the third signal from the second signal. The specific groups may have decay time constants greater than 5×10−1 seconds and less than 5×105 seconds.