SiC Composite Fuel Cladding with Zr Alloy Liner
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Solution Overview
Problem
Conventional methods for wrapping zirconium alloy tubes with SiC fibers using chemical vapor infiltration processes lead to corrosion and undermine the expected improvements due to the intense heat in nuclear reactors, particularly during accidental loss of coolant events.
Innovation Solution
Wrapping SiC fibers around a metal alloy tube, filling interstices with SiC nano-sized particles, and exposing the surface to alternating pulses of gaseous precursors containing carbon and silicon compounds to form a SiC monolayer, which increases the density and enhances corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical vapor infiltration process is used to deposit SiC onto Zr alloy tubes, then SiC coating can be formed to improve corrosion resistance, but the Zr alloy tubes suffer from corrosion and degradation during the process
Solution Approach 1:
An oxidation and corrosion resistant intermediate coating layer is applied to the Zr alloy tube surface before the SiC fiber wrapping and vapor infiltration process. This preliminary protective layer prevents the Zr alloy from suffering corrosion damage during the subsequent chemical vapor infiltration process, allowing the SiC coating to be successfully deposited without compromising the metal substrate.
2Strength
If SiC fiber wrapping is applied to improve high-temperature strength, then accident tolerance is enhanced, but pores remain in the coating that reduce effectiveness
Solution Approach 1:
SiC nano-sized particles are used to fill the pores and interstices within the SiC fiber wrapping. These fine particles penetrate and occupy the void spaces in the fibrous matrix, transforming the porous structure into a denser, more effective composite coating that maintains high-temperature strength while eliminating the detrimental effects of pores on corrosion resistance and overall performance.
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 method effectively fills all pores, improving the high-temperature strength and accident tolerance of the cladding, reducing the risk of corrosion and enhancing the fuel cycle economics by using U3Si2 fuel.
Implementation Method 1
filling the interstices of the SiC fiber wrappings with SiC nano-sized particles
Implementation Method 2
exposing the surface of the SiC wrapped tube to at least one cycle of alternating, non-overlapping pulses of gaseous precursors containing a carbon compound and a silicon compound to form a SiC monolayer
Implementation Method 3
each cycle followed by a pulse of a carrier gas to remove iodine constituents from the monolayer
Data Source
Figure 1
AI summary
A method for making a fuel rod cladding tube (20) and a cladding tube are described. The method includes wrapping ceramic fibers, for example, SiC fibers in a SiC matrix (22), around a tube (50) formed from a metal alloy, such as a zirconium alloy. The interstices of the SiC wrappings (22) on the tube (20) are at least partially filled with SiC nano-sized particles. The surface of the filled tube (20) is exposed by atomic layer deposition, at temperatures ranging from 25 C to 600 C, to at least one cycle of alternating, non-overlapping pulses of gaseous precursors containing carbon and silicon to form a SiC monolayer. The step of filling the interstices of the SiC wrappings (22) on the tube (20) with SiC nano-sized particles fills large voids in the SiC wrapping (22). The step of exposing the surface of the particle filled SiC windings to at least one cycle of gaseous pulses fills small voids in the SiC wrapping (22).