Gamma-Ray Thermometer for Direct Reactor Coolant Temperature Measurement
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Solution Overview
Problem
Conventional boiling water reactors lack a direct means to observe the temperature of coolant flowing in the reactor core, relying on indirect measurements from coolant piping, which introduces errors in performance evaluation and requires costly modifications to install in-core thermometers.
Innovation Solution
An apparatus comprising a γ-ray thermometer with a heat emission detector inside the reactor core and a thermocouple thermometer outside, along with an output signal processor to computationally determine local coolant temperatures, allowing direct observation without modifying the reactor vessel design, using a combination of γ-ray heat generation detection and thermocouple measurements with calibration heaters for accuracy and responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an in-core thermometer is installed to directly observe coolant temperature, then measurement precision is improved, but device complexity and cost increase due to reactor vessel design modification
Solution Approach 1:
The patent uses γ-ray thermometers as intermediary devices that measure temperature indirectly through γ-ray heat generation detection in the structural member, rather than direct contact with coolant. This mediator approach allows temperature observation without physical intrusion into the coolant flow path, avoiding reactor vessel modifications
Solution Approach 2:
The patent replaces the mechanical in-core thermometer installation approach with a non-mechanical γ-ray detection system. By substituting direct physical measurement with γ-ray heat generation detection, the system achieves temperature measurement without mechanical modification to the reactor vessel structure
2Reliability
If an in-core thermometer is installed to directly observe coolant temperature, then reliability is improved, but ease of manufacture deteriorates due to design modification requirements
Solution Approach 1:
The γ-ray thermometer serves as an intermediary that can be installed in the neutron detector assembly without requiring separate reactor vessel modifications. This intermediary approach maintains reliability by providing direct temperature observation while simplifying installation through existing structural pathways
Solution Approach 2:
The patent combines the γ-ray thermometer function with the existing neutron detector assembly, making the detection system multi-functional. This universal approach allows temperature measurement capability to be added without creating separate installation pathways, improving ease of manufacture
3Device complexity
If indirect coolant temperature measurement is used, then device complexity is reduced, but measurement precision deteriorates due to observation errors
Solution Approach 1:
The γ-ray thermometer acts as an intermediary measurement device that provides direct observation capability within the reactor core. This intermediary approach eliminates the need for indirect measurements from external coolant piping, improving precision while maintaining relatively simple device architecture
Solution Approach 2:
The patent substitutes indirect mechanical temperature measurement from external piping with direct γ-ray detection within the core. This substitution eliminates transmission errors and provides accurate local temperature data without requiring complex measurement systems
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 direct and accurate measurement of coolant temperatures within the reactor core, reducing errors in performance evaluation and avoiding costly design modifications, while maintaining responsiveness to temperature changes and providing cost-effective monitoring solutions.
Implementation Method 1
a γ-ray thermometer having a γ-ray heat generation detector installed in the reactor core
Implementation Method 2
a γ-ray thermometer having a γ-ray heat generation detector installed in the reactor core and a thermocouple thermometer installed out of the reactor core in the reactor vessel
Implementation Method 3
measure the temperature difference within a detector due to the exothermic phenomena in the structural member attributable to γ-rays
Implementation Method 4
A normal γ-ray thermometer contains a calibration heater so as to calibrate a differential thermocouple of a γ-ray thermometer by providing electricity to the calibration heater
Data Source
AI summary
A reactor core coolant temperature measuring apparatus for measuring the temperature of the coolant flowing in the reactor core of a nuclear reactor comprises a γ-ray thermometer having a temperature measuring section arranged below the bottom of the reactor core and a γ-ray heat generation detecting section arranged between the bottom and the top of the reactor core, a cable for transmitting the signal output from the temperature measuring section and an output signal processing means for receiving the signal and computationally determining the local temperature of the coolant at the position of placement of the temperature measuring section.