Additive Nuclear Fuel Cladding with Helical Fins
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Solution Overview
Problem
Nuclear fuel cladding with smooth surfaces and simple geometries experiences poor heat transfer due to low thermal conductivity of gases, leading to high temperature gradients and potential fuel cladding failure, which requires strict dimensional tolerances and costly machining operations.
Innovation Solution
A double-walled nuclear fuel cladding with mechanically compliant structures, such as helical fins and resilient fingers, is additively manufactured using laser powder bed fusion to enhance thermal conductivity and accommodate fuel swelling, allowing for complex geometries and improved structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If smooth cylindrical cladding is used, then manufacturing is simple, but heat transfer is poor due to low thermal conductivity of gas
Solution Approach 1:
The cladding surface is segmented into multiple protrusions distributed around the circumference, transforming the smooth surface into a multi-element structure that enhances heat transfer while maintaining manufacturing feasibility through additive manufacturing
Solution Approach 2:
The cladding surface is modified by adding radial protrusions that extend into the gap region, transitioning from a two-dimensional smooth surface to a three-dimensional structured surface that increases heat transfer area and disrupts thermal boundary layers
2Temperature
If gap size is reduced to improve heat transfer, then temperature drop is reduced, but fuel swelling causes cladding failure
Solution Approach 1:
The cladding incorporates compliant structures with elastic properties that allow dynamic adjustment of the gap size, enabling the structure to accommodate fuel swelling while maintaining thermal contact for improved heat transfer
Solution Approach 2:
The cladding material properties are changed to include elastic compliance, allowing the structure to deform and adapt to fuel dimension changes while maintaining structural integrity and thermal contact
3Reliability
If strict dimensional tolerances are applied, then cladding failure is prevented, but manufacturing cost increases
Solution Approach 1:
The cladding design transitions from requiring precise dimensional control to incorporating compliant structures with elastic properties that tolerate dimensional variations, enabling manufacturing with relaxed tolerances while maintaining reliability
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 solution significantly reduces temperature gradients and enhances heat transfer across the fuel-cladding interface, improving fuel performance and reducing the risk of cladding failure while simplifying manufacturing and maintaining structural integrity.
Implementation Method 1
additively manufactured using laser powder bed fusion
Implementation Method 2
laser powder bed fusion 3D printing
Implementation Method 3
create a direct heat conduction path from the nuclear fuel to the cladding
Implementation Method 4
enhance the mixing of the flowing coolant
Data Source
AI summary
A nuclear fuel cladding with improved thermomechanical properties is provided. The nuclear fuel cladding includes a double-walled construction having inner and outer hexagonal sidewalls. The inner sidewall and the outer sidewall are spaced apart from each other to form a cooling channel therebetween, and the inner sidewall surrounds a nuclear fuel and is spaced apart from the nuclear fuel by a small gap. Helical fins extend into the cooling channel to interconnect the inner sidewall and the outer sidewall. Resilient fingers extend toward the nuclear fuel through the small gap to comply with variations in the size of the nuclear fuel due to fabrication tolerances as well as thermal expansion and swelling of the nuclear fuel, for example UO2, when undergoing fission. The nuclear fuel cladding is formed according to an additive manufacturing process, for example laser powder bed fusion printing.