Fuel Rod Leak Testing with Argon Mass Spectrometry
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Solution Overview
Problem
Current leak testing methods for fuel rod capsules in nuclear reactors lack precision in determining leak rates due to inaccuracies caused by the use of helium as a test gas, which has similar atomic mass to hydrogen, and are influenced by residual moisture, leading to unreliable measurement results.
Innovation Solution
The use of argon as a test gas, connected to a mass spectrometer for precise concentration detection, and a test container design that allows for controlled pressure adjustments and flushing with inert gases to minimize water influence, enabling more accurate leak rate determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If helium is used as test gas for leak testing, then the testing can be performed, but measurement precision deteriorates due to similar atomic mass between helium and hydrogen causing inaccurate leak rate determination
Solution Approach 1:
The patent changes the atomic mass parameter of the test gas by substituting helium with argon. Argon has a significantly different atomic mass (40) compared to helium (4) and hydrogen (1), which eliminates the measurement interference that occurs when helium and hydrogen have similar atomic masses. This parameter change enables the mass spectrometer to accurately distinguish and measure the test gas concentration without interference from hydrogen present in residual moisture.
2Measurement precision
If residual moisture is present in the test container, then the testing environment is simplified, but measurement precision deteriorates due to interference between helium and hydrogen atomic masses
Solution Approach 1:
The patent converts the harmful interference of residual moisture into a beneficial situation. Instead of trying to completely eliminate moisture (which would be difficult and add complexity), the invention uses argon as the test gas. The mass spectrometer can clearly distinguish argon (atomic mass 40) from hydrogen (atomic mass 1) even in the presence of moisture, transforming the previously problematic interference into a non-interfering situation where moisture presence does not affect measurement accuracy.
3Adaptability or versatility
If underwater testing is used for fuel rod capsules, then the testing can be performed in situ, but measurement precision deteriorates due to water influence on gas diffusion and detection
Solution Approach 1:
The patent changes the physical-chemical parameters of the test gas by using argon instead of helium. Argon's different solubility characteristics and atomic mass provide better performance in underwater conditions. The mass spectrometer can accurately detect argon concentration despite water presence, and the gas diffusion behavior of argon in water allows for reliable leak rate calculations even when testing is performed in-situ in water-filled containers.
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 significantly enhances the precision of leak rate determination by using argon's distinct atomic mass and controlled pressure conditions, reducing measurement inaccuracies and allowing for efficient water removal, thereby improving the reliability of leak testing.
Implementation Method 1
The test gas diffuses through any leaks in the fuel rod encapsulation into the interior of the test vessel
Implementation Method 2
a mass spectrometer can be fluidically connected to the interior of the test container such that a gas stream can be supplied to the mass spectrometer to detect the concentration of the test gas
Implementation Method 3
the fuel rod inside the fuel rod capsule is heated by passing hot test gas through the capsule, thus vaporizing the water contained in the fuel rod
Data Source
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AI summary
The invention relates to a device (1) for performing a leak test on a fuel rod capsule (3), which contains at least one fuel rod (2) and test gas (P), which device (1) comprises a test container (4), which is designed to accommodate at least one fuel rod capsule (3) and can be lowered into a pool (5) of a nuclear plant flooded with water. According to the invention, a mass spectrometer (14) is fluidically connected to the interior of the test container (4) in such a way that a gas flow can be fed to the mass spectrometer (14) in order to sense the concentration of the test gas (P) that has diffused into the test container (4) from the fuel rod capsule (3).