Inductive Fuel Rod Length Sensor with Bellows Casing
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Solution Overview
Problem
Current methods for measuring radial deformations of nuclear fuel rod claddings are inefficient due to the complexity and cost of transporting irradiated rods for measurement, and existing sensors lack precision for underwater and radiative environments.
Innovation Solution
A length measuring instrument with an inductive sensor and a deformable bellows casing that allows axial deformation to transmit pressure forces while maintaining contact with the fuel rod, enabling precise measurement of radial deformations underwater and in the presence of radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If irradiated rods are extracted from the reactor pool and transported to a shielded cell for measurement, then measurement can be performed, but the process becomes complex and costly
Solution Approach 1:
The invention extracts the measurement function from the shielded cell environment and brings it directly to the reactor pool by submerging the sensor in water. This eliminates the need to transport irradiated rods to a separate measurement facility, resolving the contradiction by performing measurement in-situ while maintaining radiation shielding through the water medium.
Solution Approach 2:
Water serves as an intermediary medium that allows the inductive sensor to function in the radiative environment. The water provides both radiation shielding and a medium for force transmission to the bellows mechanism, enabling precise measurement without direct exposure to radiation while avoiding complex transport operations.
2Adaptability or versatility
If LVDT sensors are used underwater, then measurement can be performed in the radiative environment, but precision is insufficient
Solution Approach 1:
The invention replaces the direct mechanical coupling of traditional LVDT sensors with a bellows-based mechanical transmission system. The bellows mechanism transmits radial displacement forces from the fuel rod through the water medium to the sensor, maintaining precision while enabling underwater operation in the radiative environment.
Solution Approach 2:
The bellows structure acts as a flexible shell that transmits radial deformation forces while accommodating the underwater environment. The flexible bellows mechanism converts radial displacement into axial movement of the sensor core, maintaining measurement precision while enabling operation submerged in water within the reactor pool.
3Device complexity
If traditional inductive sensors are used, then structure is simple, but they cannot transmit pressure forces accurately underwater
Solution Approach 1:
The invention introduces a dynamic bellows mechanism that adapts to underwater pressure conditions. The bellows expands and contracts to transmit pressure forces accurately while maintaining the simplicity of the inductive sensor structure. This dynamic element ensures reliable force transmission from the fuel rod through water to the sensor without complicating the core inductive measurement mechanism.
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 precise, in-situ dimensional control of fuel rods without the need for transportation, allowing for accurate measurement of radial deformations and transverse dimensions with micron-level accuracy.
Implementation Method 1
an inductive sensor comprising an elongated body and a touch tip movable relative to the body along a longitudinal axis; the body of the inductive sensor contains windings and delimits a first cavity receiving a (ferro)magnetic core connected to the test tip
Implementation Method 2
the capacity for elastic deformation of the casing, along the longitudinal axis (of the body and of the sensor), is large compared to - i.e. greater than - the capacity for elastic deformation of the casing along axes orthogonal to this longitudinal axis
Data Source
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AI summary
The invention relates, in particular, to an instrument (10) for measuring length, comprising an inductive sensor (11) comprising an elongate body (14) and a tip (17) that is movable along a longitudinal axis (15). The body (14) contains windings and defines a first cavity receiving a magnetic core. The instrument further comprises a casing (13) which extends the body (14) along the longitudinal axis, and which defines, together with the body (14), a second sealed cavity (16) containing the tip (17). The capacity of the casing to resiliently deform along the longitudinal axis (15) is greater than the capacity of said casing to resiliently deform along axes that are orthogonal to said longitudinal axis.