Nuclear Fuel Assembly Coating to Reduce Neutron Absorption
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Solution Overview
Problem
Manufacturing nuclear fuel pellets with molybdenum inserts is challenging due to neutron absorption, disruption of integral fuel burnable absorbers, and high thermal neutron cross-section, leading to increased enrichment and cost, as well as difficulties in loading and coating processes.
Innovation Solution
A method involving deposition of a thermally conductive layer onto nuclear fuel layers, forming partially coated layers, which are then stacked and bonded to create a nuclear fuel assembly, using materials like zirconium and uranium diboride to enhance thermal conductivity and reduce neutron absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If molybdenum inserts are used in nuclear fuel pellets, then thermal conductivity is improved, but neutron absorption increases due to high thermal neutron cross-section
Solution Approach 1:
The patent removes molybdenum inserts from the fuel pellet structure and replaces them with a thermally conductive coating applied to the external surface. This extraction eliminates the harmful neutron absorption property of molybdenum while preserving the thermal conductivity benefit through an alternative material system (zirconium alloys, uranium diboride, or boron-containing glass).
Solution Approach 2:
The patent changes the material parameters by selecting coating materials with low thermal neutron cross-sections (zirconium alloys, uranium diboride, boron-containing glass) that have both adequate thermal conductivity and reduced neutron absorption compared to molybdenum. This parameter change resolves the contradiction between thermal conductivity and neutron absorption.
2Temperature
If molybdenum inserts are used in nuclear fuel pellets, then thermal conductivity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent extracts the complex insert installation process and replaces it with a simpler coating application. The coating is applied directly to the fuel pellet surface using conventional techniques (dipping, spraying, or coating), eliminating the need for precise insert positioning, insertion, and subsequent coating operations. This significantly simplifies manufacturing.
Solution Approach 2:
The coating is applied as a preliminary step before fuel pellet assembly and loading into fuel rods. This preliminary coating action ensures thermal conductivity is established before subsequent manufacturing steps, avoiding the need for complex multi-step processes involving inserts and post-coating operations.
3Temperature
If molybdenum inserts are used in nuclear fuel pellets, then thermal conductivity is improved, but coating process disruption occurs
Solution Approach 1:
The patent removes molybdenum inserts that disrupt the coating process and replaces them with a coating-only approach. The fuel pellet surface is prepared and coated directly without interruptions from insert installation, ensuring a continuous, uniform coating process that is not disrupted by metallic inserts or subsequent heating operations.
4Temperature
If molybdenum inserts are used in nuclear fuel pellets, then thermal conductivity is improved, but enrichment requirements increase
Solution Approach 1:
The patent changes the material parameters by selecting coating materials with low thermal neutron cross-sections (zirconium alloys, uranium diboride, boron-containing glass) that have both adequate thermal conductivity and reduced neutron absorption. This parameter change reduces the overall neutron absorption in the fuel assembly, thereby reducing the enrichment requirements for the fuel pellets.
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 enables efficient manufacturing, loading, and operation of nuclear fuel rods with improved thermal conductivity and reduced neutron absorption, lowering enrichment needs and operational costs.
Implementation Method 1
depositing a thermally conductive layer onto at least a portion of at least two nuclear fuel layers to create at least two at least partially coated layers
Implementation Method 2
depositing a thermally conductive layer onto at least a portion of at least two nuclear fuel layers
Data Source
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AI summary
A nuclear fuel assembly (430, 530) and a method of manufacture thereof are provided. The method comprises depositing a thermally conductive layer (104) onto at least a portion of at least two nuclear fuel layers (102) to create at least two at least partially coated layers (120). The method comprises stacking the at least two coated layers (120) and bonding the at least two coated layers (120) to form a nuclear fuel assembly (430, 530).