Nuclear Reactor Control Rod Drive Mechanism Assembly
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing control rod drive mechanism (CRDM) assemblies in nuclear reactors face issues with leakage and corrosion due to the use of multiple canopy seal welds, which complicates maintenance and increases the risk of reactor shutdown failures.
Innovation Solution
The CRDM assembly integrates components using a bimetallic weld or pre-fabrication to eliminate threaded connections and canopy seal welds, featuring a latch housing nozzle and latch housing as a single component, reducing the number of seal welds and enhancing seismic resilience, while maintaining the ability to control reactor reactivity through a drive rod assembly and coil stack assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple canopy seal welds are used to connect latch housing nozzle and latch housing, then the sealing capability is improved, but the risk of leakage and corrosion increases
Solution Approach 1:
The latch housing nozzle and latch housing are merged into a single integrated component through bimetallic welding or pre-fabrication, eliminating the need for separate canopy seal welds between these two parts. This integration removes the sealing interface that was prone to leakage and corrosion, while maintaining the required sealing capability through the robust bimetallic weld connection.
2Adaptability or versatility
If multiple canopy seal welds and threaded connections are used, then the assembly flexibility is improved, but the maintenance complexity increases
Solution Approach 1:
By integrating the latch housing nozzle and latch housing into one component, the number of separate connections and seals is reduced. This simplifies the overall assembly structure, making it easier to maintain and repair while still providing the necessary assembly flexibility through the retained threaded connection between the rod travel housing and latch housing.
3Strength
If multiple seal welds are used in the pressure boundary, then the structural integrity is improved, but the seismic resilience decreases
Solution Approach 1:
The integration of latch housing nozzle and latch housing eliminates one potential failure point in the pressure boundary. By reducing the number of seal welds, the structure has fewer weak points that could fail during seismic events, thereby improving seismic resilience while maintaining structural integrity through the robust bimetallic weld connection.
Solution Approach 2:
The invention extracts and removes the vulnerable canopy seal weld from the pressure boundary structure. By eliminating this particular type of seal weld through integration, the design removes a component that is susceptible to failure under seismic loading, thereby enhancing the overall seismic resilience of the CRDM assembly.
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 design reduces maintenance needs, minimizes leakage risks, and simplifies repair processes, while ensuring safe reactor shutdown and cost-effective manufacturing by eliminating the need for multiple canopy seal welds and enhancing seismic classification.
Implementation Method 1
the first end of the latch housing integrated with the second end of the latch housing nozzle by an integration mechanism selected from the group consisting of a bimetallic weld and pre-fabrication to form a single component
Implementation Method 2
The coil stack assembly includes coils which receive electrical impulses from the CRDM assembly control system. Magnetic energy generated by the coils is converted into linear motion by the latch assembly to move the drive rod assembly
Data Source
Figure 1~1C
Figure 2A~2
AI summary
The present invention relates to a control rod drive mechanism assembly for a nuclear reactor having a nuclear reactor vessel, a nuclear reactor core, a reactor vessel head, a latch housing nozzle, a latch housing, a rod travel housing, a latch assembly, a drive rod assembly and a rod control cluster assembly. The latch housing is integrated with the latch housing nozzle, the rod travel housing is welded to the latch housing, and the latch assembly is connected to the rod travel housing. The latch assembly includes the drive rod assembly and the rod control cluster assembly which is attached to the drive rod assembly.