Ternary Compound Nuclear Fuel Grids for Accident Tolerance
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Solution Overview
Problem
Conventional zirconium alloy grids and mixing vanes in nuclear reactor fuel assemblies lose strength and integrity at high temperatures, leading to potential core meltdown during Loss of Coolant Accidents, due to 'run-away' oxidation and hydrogen gas production.
Innovation Solution
The use of ternary compounds, such as Ti2AlC, Ti3AlC2, and Nb2SnC, with high temperature strength and oxidation resistance, replacing zirconium alloys in grid construction, along with advanced manufacturing techniques like hot pressing and directed energy sintering, to create stable and durable grid structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If zirconium alloy grids are used in nuclear reactor fuel assemblies, then the grids provide adequate mechanical strength and corrosion resistance at normal operating temperatures, but the grids lose strength and integrity at high temperatures during Loss of Coolant Accidents due to run-away oxidation and hydrogen gas production
Solution Approach 1:
The patent changes the material composition parameters by incorporating specific alloying elements (such as chromium, aluminum, and silicon) in controlled amounts to modify the oxidation behavior of the zirconium alloy, enabling it to resist run-away oxidation at high temperatures while maintaining mechanical integrity
Solution Approach 2:
The patent creates a composite material system by combining zirconium alloy with oxidation-resistant alloying elements, forming a multi-phase microstructure that provides both mechanical strength and oxidation resistance at elevated temperatures, preventing hydrogen production during accidents
2Strength
If conventional zirconium alloy grids are used, then the grids maintain structural integrity at normal operating conditions, but they fail to prevent core meltdown during high temperature accidents due to strength loss
Solution Approach 1:
The patent modifies the material parameters by controlling the composition ranges of alloying elements (chromium: 2-10 wt%, aluminum: 3-15 wt%, silicon: 2-10 wt%) to optimize the balance between high temperature strength retention and oxidation resistance, ensuring the grid maintains structural integrity during accidents
Solution Approach 2:
The patent creates local quality differences through controlled microstructure development, where specific phases are enriched in oxidation-resistant elements at grain boundaries and surfaces, providing localized protection against oxidation while maintaining overall structural strength at high temperatures
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 ternary compound-based grids and mixing vanes exhibit improved structure stability and oxidation resistance, preventing 'run-away' oxidation and hydrogen production, thus enhancing accident tolerance and preventing core meltdown.
Implementation Method 1
The ternary compound-based grids and mixing vanes exhibit improved structure stability and oxidation resistance, preventing 'run-away' oxidation and hydrogen production
Implementation Method 2
advanced manufacturing techniques like hot pressing and directed energy sintering, to create stable and durable grid structures
Implementation Method 3
advanced manufacturing techniques like hot pressing and directed energy sintering, to create stable and durable grid structures
Data Source
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AI summary
The invention pertains to a nuclear fuel assembly grid or a portion or a part of the grid, such as a grid strap and/or an integral flow mixer that is at least partially constructed of a composition containing one or more ternary compounds of the general formula I: Mn+1AXn wherein, M is a transition metal, A is an element selected from the group A elements in the Chemical Periodic Table, X is carbon or nitrogen, and n is an integer from 1 to 3. The invention further pertains to a method of making the nuclear fuel assembly grid or a portion of a part of the grid, by employing a sintering process to sinter the composition containing one or more ternary compounds in powder form such that the resulting grid or a portion of or a part of the grid includes a plurality of sintered layers