Twisted Ribbon Fuel Rodlet Bundle With Radial Restraint Fixtures
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Solution Overview
Problem
Existing twisted ribbon fuel rodlets in nuclear fission reactors face failure modes due to high temperature plasticity and axial force-induced twisting, along with hot hydrogen ablation issues, necessitating improvements in radial restraint and manufacturing processes to enhance durability and performance.
Innovation Solution
The implementation of geometric-specific end fixtures, fiber architectures, and advanced manufacturing methods for twisted ribbon fuel rodlets, including extrusion, twisting, and defect detection, to achieve uniform characteristics and improved radial compression within the fuel bundle, along with a multilayer casing design for enhanced structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple tube restraint system is used for twisted ribbon fuel rodlets, then device complexity is reduced, but reliability deteriorates due to fuel element plasticity, twisting failure, and hot hydrogen ablation
Solution Approach 1:
The restraint system is segmented into multiple functional components: geometric-specific end fixtures at rodlet ends, fiber architectures within the multilayer casing, and distributed support structures. This segmentation allows each component to address specific failure modes independently, improving overall reliability without requiring a single complex system
Solution Approach 2:
The fuel bundle employs a multilayer casing with composite material construction, combining different materials with complementary properties to provide radial restraint, thermal protection, and structural integrity. This composite approach enables the system to withstand high temperatures and mechanical stresses that would cause failure in simpler single-material systems
2Reliability
If geometric-specific end fixtures and fiber architectures are implemented for radial restraint, then reliability is improved, but device complexity increases
Solution Approach 1:
Geometric-specific end fixtures are pre-installed at the ends of twisted ribbon fuel rodlets during manufacturing, establishing radial restraint before the fuel bundle enters service. This preliminary action prevents deformation and failure during operation, ensuring reliability without requiring complex active control systems
Solution Approach 2:
Fiber architectures serve as intermediary elements between the fuel rodlets and the multilayer casing, providing radial restraint and stress distribution. These fiber intermediaries transfer and distribute mechanical loads, protecting the fuel rodlets from direct stress while maintaining system reliability
3Manufacturing precision
If advanced manufacturing methods including extrusion, twisting, and defect detection are used, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The manufacturing process employs continuous extrusion and twisting operations rather than batch processing, maintaining steady production flow. Defect detection is performed continuously during manufacturing, allowing immediate identification and correction without stopping production, thereby maintaining both precision and productivity
Solution Approach 2:
Traditional mechanical inspection methods are replaced with advanced non-destructive defect detection technologies that can identify manufacturing defects without physical contact or disruption to the production line. This substitution enables high-precision quality control while maintaining continuous production flow
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 effectively addresses failure modes by providing improved radial restraint, uniformity, and increased durability of twisted ribbon fuel rodlets, leading to enhanced performance and reduced failures in nuclear fission reactors, particularly in high-temperature regions.
Implementation Method 1
methods of manufacture including extrusion of ribbon fuel rodlets and twisting of ribbon fuel rodlets
Implementation Method 2
Fuel ribbons were extruded and twisted on their long axis
Implementation Method 3
strengthen the twisted ribbon fuel rodlets (and materials of the fuel bundle casing) against fracture by keeping the entire fuel bundle in radial compression
Data Source
AI summary
Fuel bundle has plurality of twisted ribbon fuel rodlets arranged hexagonal packing or circle packing arrangement in a reactor core encased in a multilayer casing. Arrangement of twisted ribbon fuel rodlets is facilitated by rodlet seating fixture with seating surface having a plurality of protrusions that form a receiving space for ends of the twisted ribbon fuel rodlets. Manufacture of the fuel bundle incorporates fiber manufacturing technologies and, optionally, infiltration of spaces in the reactor core by infiltrant. Twisted ribbon fuel rodlet manufacturing system has sub-systems that impart twist periodicity to extruded ribbons, inspect twisted extruded ribbons, and cut twisted extruded ribbons to length. Inspection sorts twisted ribbon fuel rodlets as well as provides feedback to adjust operation of sub-systems. The fuel bundle (and optional fuel bundle support) can be incorporated into a fuel assembly of nuclear propulsion fission reactor structure of, for example, a nuclear thermal propulsion engine.