Nuclear Reactor Neutron Reflector Individual Block Support
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing neutron reflector designs in gas-cooled nuclear reactors face challenges due to high mechanical stress and rapid degradation of carbon blocks under neutron irradiation and high temperatures, leading to reduced service life and complex maintenance requirements.
Innovation Solution
The design incorporates layers of wedge-shaped outer reflector blocks that support inner reflector blocks individually, reducing loading stresses and allowing for selective replacement without disassembling large portions of the reflector, along with surface features for precise positioning and through-passages for instrumentation, enabling reduced assembly time and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inner reflector blocks are stacked vertically to form the reflector structure, then the reflector provides complete neutron shielding and structural integrity, but the lower blocks bear high mechanical loads from the weight of upper blocks, accelerating radiation-induced degradation
Solution Approach 1:
The reflector is segmented into two distinct types of blocks: outer reflector blocks that form the structural framework and bear mechanical loads, and inner reflector blocks that provide neutron shielding but are individually supported to eliminate cumulative weight loading. This segmentation allows each component to be optimized for its specific function without compromising the other.
Solution Approach 2:
Outer reflector blocks serve as intermediary support structures that bear the mechanical load of inner reflector blocks. The outer blocks are positioned radially outward and provide individual support points for inner blocks, preventing the accumulation of dead weight on any single inner block while maintaining complete neutron shielding through the coordinated arrangement of both block types.
2Stability of the object's composition
If the reflector is designed as a monolithic structure, then structural integrity is maximized, but maintenance requires disassembly of large portions of the reflector, increasing downtime and operational costs
Solution Approach 1:
The reflector is divided into replaceable inner reflector blocks that can be individually removed and replaced. Each inner block is independently supported by outer blocks, allowing selective maintenance of specific blocks without requiring disassembly of the entire reflector structure or removal of adjacent blocks.
Solution Approach 2:
The support mechanism for inner reflector blocks is designed to accommodate dynamic removal and installation. The outer blocks provide support surfaces and positioning features that enable inner blocks to be easily inserted and secured, allowing the reflector to transition between operational and maintenance states without compromising structural integrity.
3Strength
If inner reflector blocks are individually supported by outer blocks with vertical gaps between them, then loading stresses are eliminated and blocks can be selectively replaced, but the structural complexity and assembly precision requirements increase
Solution Approach 1:
The outer reflector blocks are designed with specific local features including support surfaces, positioning protrusions, and recesses that precisely locate inner reflector blocks. These localized structural elements provide the necessary precision for individual block support while maintaining overall structural simplicity and facilitating easy assembly and disassembly during maintenance.
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
This approach significantly decreases stress-enhanced radiation-induced degradation, simplifies maintenance, reduces downtime, and facilitates faster reactor assembly by allowing pre-assembly of reflector segments, thereby lowering costs and crane requirements.
Implementation Method 1
A neutron reflecting structure, for example a structure formed from carbon in the form of graphite, may be placed into a reactor vessel to reflect neutrons emitted in fission events back into the reactor core
Implementation Method 2
When irradiated by neutrons, some carbon atoms are displaced, creating vacancies in the crystal lattice and lodging of atoms in interstitial sites
Data Source
AI summary
A neutron reflector design which lowers stress in inner reflector members by supporting the inner reflector members on radially adjacent outer reflector members at the interface between the inner and outer reflector members, such that an individual inner reflector member is not supported by an inner reflector member in a layer of the reflector assembly immediately below, and the inner reflector member does not have to bear a load from an inner reflector member in a layer of the reflector assembly immediately above. The lowering of the load carried by the individual inner reflector members with this individual-member-support arrangement reduces stress-induced reflector damage with is enhanced in the high radiation flux environment adjacent to a nuclear reactor core. The inner reflector members are removable for replacement without the need to remove the outer reflector members.