Reversible Clip-Fastened Nuclear Reactor Assembly Connection
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Solution Overview
Problem
Existing weldless connections in sodium fast reactors, such as those for the ASTRID reactor, face challenges in meeting mechanical strength and safety requirements due to small wall thicknesses and the need for precise positioning, with previous solutions like pressing, pegging, and clamping being unsuitable or risky, especially considering the increased radioactivity and heat generation.
Innovation Solution
A clip-fastened connection using flexible blades with a removable locking mechanism, where the flexible blades are inserted into open-ended openings within the assembly body, providing a secure and reversible connection that can withstand operational forces without generating migrating bodies in the primary coolant circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding is used to connect the upper neutron shield body to the central portion, then mechanical strength is improved, but manufacturing complexity and safety risks increase due to the need for precise positioning and the presence of fuel pins
Solution Approach 1:
The connection system is divided into separate functional elements: the connection element with flexible blades, the locking element with retaining lugs, and the central portion with recesses. This segmentation allows each component to be manufactured and positioned independently, simplifying the overall manufacturing process while maintaining connection strength.
Solution Approach 2:
The invention replaces the welding process (thermal-mechanical system) with a mechanical interlocking system using flexible blades and locking elements. This substitution eliminates the complexity of welding operations, positioning requirements, and safety risks associated with welding in the presence of fuel pins, while maintaining adequate mechanical strength through the elastic deformation and interlocking mechanism.
2Ease of manufacture
If pressing connection is used to connect the upper neutron shield body to the central portion, then manufacturing is simplified, but mechanical strength is insufficient due to small wall thicknesses
Solution Approach 1:
The invention changes the connection mechanism from direct pressing (which relies on wall thickness for strength) to a system using flexible blades that can be locked into place. The flexible blades are designed with specific elastic properties, allowing them to deform during insertion and then lock securely, providing adequate mechanical strength even with small wall thicknesses while maintaining manufacturing simplicity.
3Ease of manufacture
If pegging connection is used to connect the upper neutron shield body to the central portion, then manufacturing is simplified, but safety risks increase due to the risk of generating migrating bodies in the coolant circuit
Solution Approach 1:
Instead of using rigid pegs that could break and become migrating bodies, the invention uses flexible blades that are integral parts of the connection element. These flexible blades are designed to remain attached to the connection element throughout their service life, eliminating the risk of becoming loose bodies in the coolant circuit while maintaining manufacturing simplicity.
4Ease of manufacture
If clamping connection is used to connect the upper neutron shield body to the central portion, then manufacturing is simplified, but mechanical strength is insufficient due to the need for precise positioning
Solution Approach 1:
The invention uses flexible blades that can dynamically adapt to positioning variations through elastic deformation. The blades are designed with specific flexibility characteristics, allowing them to bend during insertion to accommodate minor misalignments and then lock securely in the recesses, providing adequate mechanical strength without requiring precise positioning while maintaining manufacturing simplicity.
5Strength
If welding is used to connect the assembly head to the central portion, then mechanical integrity is improved, but the risk of generating migrating bodies increases due to the need for welding operations with fuel pins in place
Solution Approach 1:
The invention replaces welding operations (which carry risks of generating migrating bodies such as weld spatter, slag, or defective welds) with a mechanical interlocking system using flexible blades and locking elements. This mechanical system can be assembled without welding operations in the presence of fuel pins, eliminating the associated safety risks while maintaining adequate mechanical integrity through the interlocking mechanism.
6Reliability
If the assembly uses a weldless connection, then safety is improved by eliminating welding operations, but mechanical strength may be compromised due to small wall thicknesses and positioning requirements
Solution Approach 1:
The invention changes the connection mechanism from direct structural connection (which would require thick walls for strength) to a system using flexible blades with specific elastic properties. The blades are designed with optimized flexibility and locking characteristics, allowing them to provide adequate mechanical strength through elastic deformation and interlocking, even with small wall thicknesses, while maintaining the safety benefits of a weldless connection.
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 clip-fastened connection simplifies manufacturing and thermomechanical sizing, ensures mechanical integrity, allows for multiple reuse of assembly components, and prevents the risk of bodies migrating in the coolant, meeting the requirements of mechanical strength and safety while being adaptable to various reactor designs.
Implementation Method 1
at least one flexible blade of which the free end is shaped into a clip-fastening hook collaborating in clip-fastening with the open-ended opening
Data Source
AI summary
An assembly to be inserted into a nuclear reactor, such as a liquid sodium-cooled fast neutron reactor, includes an assembly hollow body of elongate shape along a longitudinal axis X. The wall of the hollow body includes at least one through-opening. The assembly also includes an assembly element inserted into the hollow body. The assembly element includes at least one flexible blade of which the free end is shaped into a clip-fastening hook collaborating in clip-fastening fashion with the through-opening from inside the hollow body, so as to connect the assembly element to the hollow body. The assembly also includes at least one removable structure for locking the flexible blade clip-fastened into the through-opening. The removable locking structure makes it possible to prevent the flexible blade from flexing and thus the removable locking structure makes it possible to lock a connection between the assembly element and the hollow body.