Tube Deformation Analysis Using Constrained Ballooning Zones
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Solution Overview
Problem
Conventional methods for analyzing the maximum circumferential deformation of fuel cladding materials in nuclear power plants underestimate the maximum deformation due to ballooning occurring at tube ends rather than the sensor's mid-plane, leading to inaccurate and underestimated deformation measurements.
Innovation Solution
A system for analyzing diametrical deformation of a tube that includes a deformation limiter to delimit an area beyond nominal deformation, allowing for measurement of maximum admissible circumferential deformation by positioning the sensor at the ballooning zone, ensuring accurate and representative measurements of accidental or incidental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor is positioned at the mid-plane of the tube, then the measurement system is simple and easy to operate, but the maximum deformation is underestimated because ballooning occurs at the tube ends rather than at the sensor location
Solution Approach 1:
A deformation limiter is introduced as an intermediary component between the tube and the sensor. This limiter includes a limiting surface that contacts the tube at its ends and restricts deformation beyond a nominal value, causing ballooning to occur at the tube ends rather than at the sensor location. The sensor positioned at the mid-plane can then accurately measure the maximum deformation that occurs at the limited zones.
2Reliability
If the pressure ramp is applied to achieve representative strain rates, then the test conditions are accurate, but the rupture may occur at tube ends away from the sensor, leading to loss of measurement data
Solution Approach 1:
The deformation limiter is pre-installed on the tube before the pressurization test begins. The limiting surfaces are positioned to contact the tube ends at predetermined locations, establishing the zones where ballooning will occur. This preliminary action ensures that when pressure is applied and rupture occurs, the deformation maximum will be at the sensor location, preventing loss of measurement data.
3Ease of operation
If the sensor measures deformation at the mid-plane, then the measurement system is simple, but the measured deformation does not represent the maximum deformation of the material
Solution Approach 1:
The deformation limiter creates local zones of constrained deformation at the tube ends, while the mid-plane region allows free deformation and ballooning. This local quality differentiation ensures that the sensor at the mid-plane measures the true maximum deformation, while the limiter zones prevent unwanted ballooning at other locations.
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
The system provides more relevant and accurate measurements of maximum deformation by ensuring the rupture occurs in line with the sensor, maintaining representative strain rates and enabling in situ measurement of deformations, thus overcoming the limitations of conventional methods.
Implementation Method 1
a diametral sensor (120) to monitor the deformation of the sheath (20)
Implementation Method 2
A pressure ramp is applied inside the sheath (20) thanks to the injection of oil by the fluid injector (130)
Data Source
Figure 1~2
Figure 3
AI summary
The present invention concerns a system (1) for analysing the diametrical deformation of a tube (2), comprising a sensor (12) to monitor the deformation of the tube (2), characterised in that it further comprises a deformation limiter (14, 15) for restricting to an area (21) of the tube at a right angle to the senor (12) the extent of an additional deformation of the tube (2) that goes beyond a nominal deformation.