CRDM Latch Engagement and Holding Separation
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Solution Overview
Problem
Existing control rod drive mechanisms (CRDMs) for nuclear reactors face inefficiencies in energy usage due to the combined functions of latch engagement and holding, where the latch engagement mechanism is required to perform high-energy operations frequently, while the latch holding mechanism handles lower-energy operations throughout the fuel cycle, leading to suboptimal energy efficiency.
Innovation Solution
The CRDM design separates latch engagement and holding functions, employing a self-engaging cam/latch system where gravity biases the latch closure, and a separate holding mechanism using electromagnets to maintain latch engagement, reducing operational power requirements and simplifying manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the latch engagement mechanism performs both engagement and holding functions, then the mechanism can be simpler in structure, but the energy consumption increases because the engagement mechanism must continuously maintain latch closure
Solution Approach 1:
The patent divides the latch system into two independent mechanisms: a latch engagement mechanism that closes the latch during control rod movement, and a separate latch holding mechanism that maintains latch closure during stationary periods. This segmentation allows each mechanism to be optimized for its specific function, with the holding mechanism consuming minimal energy while the engagement mechanism handles the high-energy closing action.
Solution Approach 2:
The patent extracts the latch holding function from the engagement mechanism and implements it through a separate holding mechanism. This extraction eliminates the need for the engagement mechanism to continuously consume energy to maintain latch closure, as the holding mechanism takes over this function using a different, more energy-efficient approach.
2Reliability
If the latch engagement mechanism continuously maintains latch closure, then the latch remains reliably engaged, but the power requirements increase during normal operation
Solution Approach 1:
The patent implements periodic action by having the engagement mechanism close the latch only when needed during control rod movement, then transferring to the holding mechanism for maintenance of latch closure. This periodic engagement followed by separate holding reduces continuous power consumption while maintaining reliability through the dedicated holding mechanism.
Solution Approach 2:
The holding mechanism is designed to maintain latch closure passively without requiring continuous active power input, allowing the system to maintain reliability with minimal operational power requirements.
3Ease of manufacture
If a single mechanism handles both latch engagement and holding, then the system has fewer components, but the manufacturing complexity increases due to the demanding requirements on the engagement mechanism
Solution Approach 1:
By segmenting the latch system into separate engagement and holding mechanisms, each component can be manufactured with optimized tolerances and specifications appropriate to its specific function, rather than requiring the engagement mechanism to meet all performance requirements including continuous holding capability.
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 separation of functions enhances energy efficiency by minimizing the power needed for latch holding and activation, allowing reliable SCRAM operations while reducing operational costs and manufacturing complexity.
Implementation Method 1
the four-bar linkage is configured to bias the latches closed under force of gravity
Implementation Method 2
a separate holding mechanism using electromagnets to maintain latch engagement
Data Source
AI summary
A control rod drive mechanism (CRDM) configured to latch onto the lifting rod of a control rod assembly and including separate latch engagement and latch holding mechanisms. A CRDM configured to latch onto the lifting rod of a control rod assembly and including a four-bar linkage closing the latch, wherein the four-bar linkage biases the latch closed under force of gravity.