Nuclear Fuel Cladding Testing With Rapid Joule Heating
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Solution Overview
Problem
Existing mechanical testing devices for nuclear fuel cladding do not accurately simulate the rapid temperature increases and mechanical stresses experienced during reactor accidents, with prior methods failing to replicate the extreme conditions of up to 1,000 °C/s temperature rise rates.
Innovation Solution
A device and method using movable compression pistons with an electrically conductive winding and an electrical generator to induce rapid temperature increases and mechanical deformations, allowing for monoaxial or biaxial testing of tubular samples under accident conditions, achieving temperature rise rates of 400 to 800 °C/s.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional heating methods are used to heat the cladding sample, then the heating process is controllable and safe, but the temperature rise rate is limited to 100-200 °C/s which is far from real accident conditions
Solution Approach 1:
The patent replaces conventional mechanical/electrical heating systems with a electromagnetic induction heating system. The induction heating coil generates an electromagnetic field that directly induces eddy currents in the cladding sample, achieving rapid heating rates of up to 1,000 °C/s that accurately simulate real accident conditions while maintaining controlled experimental conditions.
Solution Approach 2:
The patent utilizes the phase transition capability of the deformable cylindrical core material (from solid to liquid) at a specific melting temperature. This phase transition serves as a visual indicator and mechanical softening mechanism during the compression test, allowing researchers to observe and measure the cladding's mechanical behavior at elevated temperatures under accident-like conditions.
2Speed
If the compression pistons are made electrically conductive to enable induction heating, then rapid temperature increase can be achieved, but the device complexity increases
Solution Approach 1:
The patent merges the compression piston function with the induction heating coil function. The compression pistons are made electrically conductive and serve dual purposes: applying mechanical compression force to the cladding sample and acting as the induction heating coil to generate rapid heating through electromagnetic induction. This integration eliminates the need for separate heating components, reducing overall device complexity while achieving the desired heating speed.
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 mechanical testing of nuclear fuel cladding under accident conditions, replicating the extreme temperature and stress conditions, providing accurate mechanical data for safety assessments.
Implementation Method 1
an electrical generator adapted to circulate an electric current between the two compression pistons and in said winding
Implementation Method 2
two compression pistons movable relative to each other along a clamping axis... in a second compression sequence in which the two compression pistons are disconnected from the electrical generator and compress the cylindrical core
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Device and method for mechanical testing of a tubular sample (1) of nuclear fuel cladding under accident conditions, comprising: - a deformable cylindrical core (5) adapted to be arranged in a mechanical test space (4), being inserted into the tubular sample (1), this deformable cylindrical core (5) comprising at its periphery a winding (11) of an electrically conductive wire (12), this winding (11) comprising a first connection end (14A) adapted to be electrically connected to one of the compression pistons (2), and which comprises a second connection end (14B) adapted to be electrically connected to the other compression piston (2); - an electric generator (19) adapted to circulate an electric current between the two compression pistons (2) and in said winding (11).