BWR Control Rod Grapple for Simultaneous Component Removal
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Solution Overview
Problem
Conventional grapple systems for Boiling Water Reactors (BWRs) require separate operations to remove control rods, fuel support castings, and control rod guide tubes, increasing the time and complexity of refueling and maintenance operations due to the need for multiple grapples and sequential handling.
Innovation Solution
A single grapple system that simultaneously removes control rods, fuel support castings, and control rod guide tubes using pneumatically actuated hooks to grip and lift all components as a single unit, reducing the time and effort required during refueling and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate grapples are used to remove control rod blade, fuel support casting, and control rod guide tube, then each component can be handled with dedicated gripping mechanisms, but the refueling and maintenance outage time increases due to sequential operations
Solution Approach 1:
The patent combines multiple separate grapple systems into a single integrated grapple assembly that can simultaneously handle the control rod blade, fuel support casting, and control rod guide tube. This merging of functions allows all three components to be removed in one operation rather than sequentially, directly reducing outage time while maintaining reliable handling of each component through dedicated hooks and gripping mechanisms.
Solution Approach 2:
The grapple assembly is designed as a universal tool that performs multiple functions: it can grip control rod blades via bail handles, grasp fuel support castings, and engage control rod guide tubes through orifice holes. This multi-functional design eliminates the need for separate specialized grapples for each component, enabling simultaneous removal operations and reducing overall maintenance outage duration.
2Reliability
If multiple separate grapples are used for different components, then each component can be removed with specialized gripping mechanisms, but the device complexity and number of equipment pieces increases
Solution Approach 1:
The patent merges multiple separate grapple systems into one integrated assembly, reducing equipment complexity while maintaining specialized gripping capabilities. The single grapple includes CRB hooks for control rod blades, FSC hooks for fuel support castings, and CRGT hooks for guide tubes, all integrated into one structure that can be deployed simultaneously rather than requiring multiple separate devices.
Solution Approach 2:
The grapple assembly serves as a universal multi-functional tool that can handle three different component types with dedicated mechanisms for each. This consolidates what would otherwise require three separate specialized grapples into one device, reducing overall system complexity while preserving reliable component-specific gripping through tailored hook designs and engagement mechanisms.
3Ease of operation
If separate grapples are used for control rod blade and control rod guide tube, then each can be handled independently, but the number of operations and procedural steps increases
Solution Approach 1:
The patent combines independent handling capabilities for control rod blades and guide tubes into a single simultaneous operation. The grapple assembly engages both components at the same time using dedicated CRB hooks and CRGT hooks, allowing them to be removed together in one lifting action rather than requiring separate sequential operations, thereby improving refueling efficiency while maintaining ease of independent component handling.
4Ease of manufacture
If conventional separate grapple operations are used, then each component can be removed with simple individual mechanisms, but the overall process duration and maintenance outage increases
Solution Approach 1:
The patent merges multiple simple individual grapple mechanisms into one integrated assembly that performs all removal operations simultaneously. While each individual gripping mechanism remains relatively simple (hooks, latches, engagement features), their integration into a single deployable unit enables concurrent removal of control rod blades, fuel support castings, and guide tubes, dramatically reducing maintenance outage duration without significantly complicating the underlying mechanisms.
Data Source
AI summary
A method and apparatus for grasping and lifting a boiling water reactor (BWR) control rod using a grapple. The grapple may grasp the control rod blade, the fuel support casting and the control rod guide tube of the control rod, to lift and move all three of these components in unison. The grapple includes a frame, a control rod blade hook, a fuel support casting hook(s) and a control rod guide tube hook(s). The control rod guide tube hook(s) may have a distal end that extends through a side flow orifice of a fuel support casting and beyond the confines of a control rod guide tube flow orifice to grasp the control rod guide tube. The distal end of the control rod guide tube hook(s) may include inner and outer landing surfaces, providing respective support for the fuel support casting and control rod guide tube.