Nuclear Reactor Fuel Element Support System
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Solution Overview
Problem
Current nuclear reactor support grids are difficult to inspect and replace, especially when using heavy liquid metals as coolants, due to neutron flux and structural interference issues, and existing solutions are limited to specific fuel element patterns and require bulky anchoring systems.
Innovation Solution
A support system for fuel elements where each element has a mechanically flexible connection shaft with spherical coupling and integrated support devices that allow vertical and radial constraint, enabling easy replacement and thermal expansion management, eliminating the need for a traditional support grid and allowing for flexible fuel element installation and cooling gas injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional support grid is used to hold fuel elements, then the fuel elements are securely supported, but the support grid becomes difficult to inspect and replace due to neutron flux and structural interference
Solution Approach 1:
The support grid is divided into individual support elements that can be independently replaced. Each support element holds one or more fuel elements and can be detached and replaced without removing the entire support grid structure, enabling easy inspection and maintenance of individual components.
Solution Approach 2:
The support elements are designed with movable and detachable connections to the support grid. The support elements can be dynamically inserted, removed, and repositioned, transforming the static support grid into a dynamic system that allows easy access for inspection and replacement of individual support elements.
2Object-affected harmful factors
If fuel elements are extended in length beneath the active part to reduce damage to the support grid, then neutron flux damage is reduced, but the overall structure becomes more complex and occupies more space
Solution Approach 1:
The support function is extracted from the fuel element itself and transferred to separate support elements. This allows the fuel element to have optimized lengths for minimizing neutron flux damage while the support elements provide the necessary structural support and positioning, separating the support function from the fuel element design.
3Ease of operation
If a support structure with beams passing through penetrations is used, then fuel elements can be supported and replaced, but the penetrations pass through the primary confining barrier and require bulky sliding beams
Solution Approach 1:
The support structure is segmented into discrete support elements that can be independently operated. Each support element can be detached and replaced without requiring bulky sliding beams or penetrating the primary confining barrier, simplifying the overall structure while maintaining ease of fuel element replacement.
4Temperature
If heavy liquid metals are used as primary coolant, then cooling efficiency is improved, but a serious floating effect occurs requiring complicated anchorage and balancing with high-density materials
Solution Approach 1:
The support elements are designed with density and geometric characteristics that counterbalance the floating effect of heavy liquid metal coolant. The support elements provide downward force to compensate for the buoyancy of the fuel elements in the heavy coolant, eliminating the need for complicated anchorage systems while maintaining cooling efficiency.
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
Facilitates easy fuel element replacement, reduces neutron and thermal damage, eliminates overhanging structures for improved maintenance access, and introduces a safety factor through controlled radial expansion and cooling, enhancing reactor safety and operational efficiency.
Implementation Method 1
mechanically flexible connection shaft with spherical coupling
Implementation Method 2
integrated support devices that allow vertical and radial constraint, enabling easy replacement and thermal expansion management
Implementation Method 3
mechanically flexible connection shaft
Data Source
AI summary
A nuclear reactor is provided that comprises a vessel that houses a core, comprising a bundle of fuel elements, and immersed in a primary cooling fluid of the core; the fuel elements extend along respective longitudinal and parallel axes and are mechanically supported by respective heads joined to each other and joined to an anchoring structure by support devices acting between adjacent fuel elements, or acting between fuel elements situated on the periphery of the core and the anchoring structure, and which constitute an integral part of the heads of the fuel elements.