SiC Fuel Rod Pressurization via Spring-Loaded End Plug
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Solution Overview
Problem
There is a need for a practical method to efficiently pressurize nuclear fuel rods with ceramic cladding, specifically silicon carbide (SiC), as existing high-temperature sealing processes are challenging and often conducted in a vacuum, especially when filling the interior void area with a thermally conductive gas like helium.
Innovation Solution
A method involving a lower and upper end plug fixture system that forms a gas-tight seal, using a spring to bias the active element, and a pressure chamber to introduce and maintain a preselected pressure of a filler gas within the cladding, which can be sealed using mechanical or chemical means, allowing for the use of a binding agent to enhance the seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature sealing processes are used to seal SiC cladding, then gas-tightness is achieved, but the process complexity increases and vacuum conditions are required
Solution Approach 1:
The end plug is divided into two separate components: an end plug body and an end plug seal. This segmentation allows the sealing function to be独立 from the structural function, enabling simpler sealing processes that do not require high temperatures or vacuum conditions, while still achieving reliable gas-tightness.
Solution Approach 2:
A dedicated end plug seal component acts as an intermediary between the end plug body and the SiC cladding. This intermediary element provides the sealing function through simple contact pressure from the spring-loaded mechanism, eliminating the need for complex high-temperature sealing processes.
2Reliability
If high-temperature sealing processes are used to seal SiC cladding, then gas-tightness is achieved, but the manufacturing cost and time increase
Solution Approach 1:
By separating the sealing function into an independent end plug seal component, the sealing process can be performed using simple spring-loaded contact pressure at room temperature. This eliminates the need for energy-intensive high-temperature processes, significantly reducing manufacturing time and cost while maintaining gas-tightness.
Solution Approach 2:
The sealing approach changes from high-temperature thermal processes to room-temperature mechanical contact pressure. This parameter change in the sealing mechanism enables faster, cheaper manufacturing while achieving the same gas-tightness result through the spring-loaded end plug seal.
3Stress or pressure
If spring-loaded end plug is used to pressurize SiC cladding, then pressurization is achieved, but the end plug must be sealed after pressurization
Solution Approach 1:
The end plug is segmented into a body and a seal component. The body provides the pressurization function through the spring-loaded mechanism, while the separate seal component provides the sealing function. This segmentation allows the pressurization and sealing functions to be independently optimized and simplified.
Solution Approach 2:
The spring-loaded end plug automatically provides both pressurization and sealing functions. The spring force simultaneously pressurizes the interior of the SiC cladding and maintains contact pressure on the end plug seal to ensure gas-tightness, eliminating the need for separate sealing operations.
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
Enables efficient pressurization of SiC clad nuclear fuel rods in a production line environment, maintaining the integrity of the ceramic material while ensuring a gas-tight seal, thus addressing the limitations of existing high-temperature processes.
Implementation Method 1
a spring inserted within the empty plenum between the upper end of the cladding and the active element... the spring being configured to bias the active element towards the lower end plug
Implementation Method 2
introduces a filler gas into the pressure chamber, and raises the pressure of the filler gas within the pressure chamber to a preselected pressure for a given period of time
Implementation Method 3
closing off a lower end of the cladding with a lower end plug fixture configured to form a gas tight seal... closing off the upper end of the cladding with an upper end plug fixture
Data Source
AI summary
An apparatus and method for pressurizing SiC clad rods of a nuclear core component. A lower end of the rod is sealed with a lower end plug and an upper end of the rod is sealed between the cladding and an external piece of an upper end plug that has a through opening through which a separate internal piece of the upper end plug extends. The internal piece of the upper end plug is initially moveable within the through opening between an upper position that forms a gas tight seal and a lower position that forms a gaseous path through the through opening. The rod is placed in a pressure chamber pressurized to a desired pressure. When the pressure is reduced within the pressure chamber the internal pressure in the rod biases the internal piece of the upper end plug in the upper sealed position.