Annulus Spacer Position Detection via Temperature Gradient

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Solution Overview

Problem

Existing methods struggle to accurately locate annulus spacers between concentric tubes in nuclear reactor fuel channels, particularly tight-fitting spacers, due to the absence of a detectable girdle wire, leading to challenges in ensuring correct positioning and meeting functional, safety, and performance requirements.

Innovation Solution

A probe head assembly with temperature sensors is used to detect temperature abnormalities along the interior surface of the interior tube, creating a temperature gradient to identify the position of annulus spacers by measuring temperature variations, allowing for precise localization without the need for eddy current testing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If eddy current testing is used to detect annulus spacer position, then detection capability is provided for loose-fitting spacers with girdle wire, but tight-fitting spacers without girdle wire cannot be detected

Engineering Contradiction:

Improvespacer position detection accuracyVSAvoiddetection method applicability to different spacer types

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent replaces eddy current testing (electromagnetic method) with temperature gradient detection (thermal method). The temperature sensor detects thermal signatures of spacers regardless of their electrical conductivity or girdle wire presence, enabling universal detection of both loose-fitting and tight-fitting spacers through thermal field rather than electromagnetic field

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the detection parameter from electrical conductivity (eddy current) to thermal conductivity (temperature gradient). By measuring temperature distribution and gradients along the tube instead of electrical signals, the system can detect all spacer types that create thermal disturbances, achieving both precise measurement and broad adaptability

Inventive Principle:

Principle #35Parameter changes

2Reliability

If tight-fitting spacers are used to maintain annular gap, then spacer reliability is improved, but detection capability is lost due to absence of girdle wire

Engineering Contradiction:

Improveannular gap maintenance reliabilityVSAvoidspacer location detectability

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent substitutes electromagnetic detection (eddy current requiring conductive girdle wire) with thermal detection (temperature sensing). This allows detection of tight-fitting spacers that maintain reliable mechanical contact without requiring electrical conductivity, as all spacers create thermal signatures detectable by temperature sensors

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The temperature acts as an intermediary parameter that indirectly reveals spacer presence and position. Instead of directly detecting the spacer's physical or electrical properties, the system measures temperature distribution and gradients in the surrounding medium, which are altered by the spacer's thermal characteristics and position

Inventive Principle:

Principle #24Intermediary (Mediator)

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 method enables accurate detection of annulus spacer positions with a tolerance of about 15 mm or better, ensuring correct positioning and meeting various requirements, even for tight-fitting spacers, thereby enhancing safety and performance in nuclear reactor fuel channels.

Implementation Method 1

when a temperature gradient is present therebetween

Methodology Applied

Scientific EffectTemperature gradient: Temperature Gradient

Data Source

PatentUS9196387B2Apparatus and method for detecting position of annulus spacer between concentric tubes

Publication Date: 2015.11.24 ATOMIC ENERGY OF CANADA LIMITED

AI summary

An apparatus for detecting the location of at least one annulus spacer between concentric interior and exterior tubes when a temperature gradient is present therebetween. A probe head assembly is movable within the interior tube. At least one temperature sensor is coupled to the probe head assembly and configured to detect a temperature of an interior surface of the interior tube. A drive assembly is operable to move the probe head assembly relative to the interior tube. A data acquisition system is coupled to the at least one temperature sensor and configured to receive a plurality of temperature measurements in order to identify at least one position along the interior surface having a temperature abnormality corresponding to a reduced temperature gradient.