Pivoting Control Rod Drive Extractor for Nuclear Reactor Refueling
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Solution Overview
Problem
Current methods for replacing control rod drives in nuclear reactors during refueling outages are time-consuming and costly, requiring manual removal, transportation, and reinstallation, which increases exposure to radiation and prolongs under-vessel activities.
Innovation Solution
A control rod drive replacement device and method that includes dual channels and extractors pivotally mounted under a nuclear reactor pressure vessel, allowing for simultaneous removal and installation of control rod drives in a vertical orientation, reducing the need for manual handling and minimizing radiation exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If manual removal and transportation of control rod drives is used, then the process is simple to operate, but the time required and radiation exposure increase significantly
Solution Approach 1:
The device employs a movable housing that can pivot between horizontal and vertical orientations, allowing dynamic adaptation to different operational phases (removal vs. installation). This dynamic configuration enables the same device to perform multiple functions efficiently, reducing overall time while maintaining operational simplicity through automated positioning mechanisms
Solution Approach 2:
The control rod drive extractor is nested within the housing, which itself is nested within the channel structure. This nested arrangement allows compact storage and streamlined transportation of components, reducing the space required under the pressure vessel and minimizing the complexity of manual handling while enabling rapid deployment
2Productivity
If dual channels with extractors are used, then productivity increases through simultaneous operations, but device complexity increases
Solution Approach 1:
The device is segmented into two independent channels, each with its own extractor and housing. This segmentation allows simultaneous independent operations (removal in one channel, installation in the other), doubling productivity. The modular segmented design actually reduces overall complexity by allowing each segment to be standardized and independently maintained
Solution Approach 2:
Each channel assembly is designed as a universal module that can perform both removal and installation functions. The housing can pivot to accommodate different orientations, and the extractor can handle both extraction and insertion operations. This multi-functionality reduces the need for separate specialized devices, thereby managing complexity while maximizing productivity
3Object-affected harmful factors
If vertical orientation for receiving control rod drives is used, then radiation exposure is minimized, but the mechanism requires more complex movement between orientations
Solution Approach 1:
The housing is designed to dynamically pivot between horizontal and vertical orientations based on operational needs. During installation, the vertical orientation minimizes radiation exposure by keeping the open end away from the pressure vessel. The dynamic capability to change orientation is achieved through hinge mechanisms and guide rails that simplify the movement process
Solution Approach 2:
The channel is designed with guide rails and support structures that create equipotential pathways for the housing movement. This ensures that the transition between horizontal and vertical orientations occurs along a predetermined safe path, minimizing additional complexity by using gravity-assisted movement and standardized mounting interfaces
Data Source
AI summary
A control rod drive replacement device includes a channel for mounting on a support under a nuclear reactor pressure vessel and a control rod drive extractor removably received in the channel. The control rod drive extractor includes a base and a housing pivotably connected to the base. The housing is configured for receiving a control rod drive. The base includes a base axis. The housing is pivotably attached to the base at the base axis for pivoting between a horizontal orientation in which the housing is aligned within the channel and a vertical orientation in which the housing is aligned for receiving the control rod drive from the nuclear reactor pressure vessel. The housing is vertically movable with respect to the base in the vertical orientation.