Control Rod Drive Mechanism Foreign Substance Removal
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Solution Overview
Problem
Current methods for removing foreign substances from control rod drive mechanisms in nuclear power plants are inefficient, as they require shutdowns, increase radiation exposure risks, and pose challenges in managing complex structures, leading to reduced management efficiency and safety concerns.
Innovation Solution
A method and device that utilize individually controlled coils (stationary gripper coil, movable gripper coil, and lift coil) to drive parts of the control rod drive mechanism, allowing for the removal of foreign substances without shutting down the power plant, by activating and deactivating these coils to manipulate the driving shaft and its components, thereby facilitating the removal of foreign substances within the mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If foreign substances are removed through withdrawal or insertion operation of the control rod, then foreign substances can be removed from the control rod drive mechanism, but the control rod may slip or fall
Solution Approach 1:
The control rod drive mechanism is divided into multiple independently controllable segments (first part with stationary gripper coil, second part with movable gripper coil, third part with lift coil). This segmentation allows individual parts to be activated for foreign substance removal without moving the entire control rod, preventing slippage or falling while enabling targeted cleaning operations.
2Reliability
If foreign substances are removed during planned preventive maintenance period, then foreign substances can be removed from the control rod drive mechanism, but management costs increase and personnel are exposed to radiation
Solution Approach 1:
The control rod drive mechanism is equipped with self-service capability for foreign substance removal through its own coils (stationary gripper coil, movable gripper coil, lift coil). The mechanism can perform maintenance operations on itself during normal operation without requiring external personnel intervention, thereby eliminating radiation exposure risks and reducing management costs.
3Reliability
If the control rod drive mechanism is shut down to remove foreign substances, then foreign substances can be removed safely, but plant operation is interrupted and downtime increases
Solution Approach 1:
The control rod drive mechanism maintains continuous operation while performing foreign substance removal. By selectively activating individual coils (first part, second part, or third part) without shutting down the power plant, the system enables maintenance operations to proceed concurrently with normal power generation activities, ensuring uninterrupted productivity.
4Reliability
If personnel are deployed to remove foreign substances manually, then foreign substances can be removed from the control rod drive mechanism, but management efficiency is reduced and personnel safety is compromised
Solution Approach 1:
Manual mechanical operations by personnel are replaced with an automated electromagnetic system consisting of coils (stationary gripper coil, movable gripper coil, lift coil). This substitution eliminates the need for personnel deployment, improving management efficiency while maintaining effective foreign substance removal capability through automated control sequences.
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 and safe removal of foreign substances during plant operation, reducing radiation exposure risks and improving maintenance efficiency by allowing for the removal of substances without manual intervention, thus enhancing operational safety and reducing downtime.
Implementation Method 1
activating at least one of the stationary gripper coil, the movable gripper coil, and the lift coil to drive the first part, the second part, or the third part
Data Source
AI summary
A method of removing floating foreign substances that may interfere with a normal operation of an electromechanical mechanism of a control rod drive mechanism and a device for executing the same are provided. The method of removing the foreign substances from the control rod drive mechanism comprising a driving shaft including a plurality of teeth and disposed in a vertical direction in the control rod drive mechanism, a first part configured to hold or release a lower end portion of the driving shaft depending on whether a stationary gripper coil is activated, a second part configured to hold or release an intermediate portion of the driving shaft depending on whether a movable gripper coil is activated, and a third part configured to move the second part in the vertical direction depending on whether a lift coil is activated may include: activating at least one of the stationary gripper coil, the movable gripper coil, and the lift coil to drive the first part, the second part, or the third part in a state in which the driving shaft is not able to move; and removing the foreign substances from the first part, the second part, or the third part.