Magnetic Jack Drive Mechanism for Nuclear Reactor Control Elements
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Solution Overview
Problem
Conventional magnetic jack type control element drive mechanisms for nuclear reactors suffer from magnetic force loss and require cooling systems, making them less efficient and more complex, especially under high-temperature, high-pressure, and high-radiation conditions.
Innovation Solution
A magnetic jack type in-vessel control element drive mechanism is designed with mineral-insulated coils and martensitic stainless steel or austenitic stainless steel components to minimize magnetic force loss, featuring an upper and lower coil assembly, a connecting member, a support tube, and a motor assembly that ensures full magnetic flux transfer, eliminating the need for a cooling system and simplifying assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional motor housing is used to house the motor assembly, then the structure is simple, but magnetic flux is lost as it bypasses through the housing, reducing magnetic force
Solution Approach 1:
The patent employs a composite structure consisting of a motor housing made from non-magnetic material (such as aluminum alloy or plastic) combined with a separate magnetic flux guide component made from magnetic material (such as soft iron or permalloy). This composite construction allows the housing to provide mechanical support while the magnetic flux guide component directs and concentrates the magnetic flux onto the motor assembly, preventing flux loss and enhancing magnetic force without significantly increasing overall structural complexity.
2Duration of action of stationary object
If cooling air is provided to remove heat from coils, then the coils can operate continuously, but the system becomes more complex and requires additional cooling components
Solution Approach 1:
The patent implements self-cooling of the coils by utilizing the natural convection of air through the coil windings and the thermal conductivity of the coil support structure. The coil assembly is designed with adequate spacing between turns and layers to allow air circulation, and the support structure conducts heat away from the coils to the reactor vessel wall or surrounding coolant, enabling continuous operation without additional active cooling systems.
3Force
If grooves are formed on the motor housing to compensate for magnetic force loss, then some magnetic force is recovered, but the structure becomes more complex and the compensation is insufficient
Solution Approach 1:
The patent extracts the magnetic flux guiding function from the motor housing structure by introducing a separate, dedicated magnetic flux guide component. This component is specifically designed and positioned to intercept and direct magnetic flux onto the motor assembly, separating the flux management function from the mechanical housing function. This approach provides effective magnetic force compensation without the complexity of modifying the housing with grooves or other structural features.
4Reliability
If a conventional control element drive mechanism is used, then it can operate in standard conditions, but it cannot withstand high-temperature, high-pressure, and high-radiation environments
Solution Approach 1:
The patent addresses harsh environment operation by selecting materials with appropriate properties for high-temperature, high-pressure, and high-radiation conditions. The motor housing and internal components are made from materials such as aluminum alloys, stainless steels, or ceramic composites that maintain structural integrity and electrical insulation properties under reactor conditions. The coil insulation is selected to withstand elevated temperatures and radiation exposure, ensuring reliable operation in the specified harsh environment.
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
The solution enhances magnetic force transfer, reduces assembly complexity, and allows operation under harsh conditions without a cooling system, improving efficiency and reliability in high-temperature, high-pressure, and high-radiation environments.
Implementation Method 1
The control element drive mechanism includes four coils, i.e., an upper lifting (UL) coil 510, an upper gripper (UG) coil 520, a lower lifting (LL) coil 530, and a lower gripper (LG) coil 540, and controls the vertical movement of the control element 3 by controlling magnetic force generated by the coils.
Implementation Method 2
The considerable amount of magnetic flux generated by the above-mentioned driving coils is not transferred to the motor assembly but bypasses through the motor housing 560, thereby causing a reduction in magnetic force.
Data Source
AI summary
A magnetic jack type in-vessel control element drive mechanism includes: an upper coil assembly which includes a first sleeve configured to coaxially wrap a control element drive shaft, a first coil, and a first coil housing which is externally coupled to the first sleeve; a lower coil assembly which includes a second sleeve configured to coaxially wrap the control element drive shaft, a second coil, and a second coil housing which is externally coupled to the second sleeve, wherein the lower coil assembly is located under the upper coil assembly, a connecting member which connects the upper coil assembly and the lower coil assembly; a support tube which extends downward from the lower coil assembly; a motor assembly which is located between the control element drive shaft, and the first and second sleeves; and an anti-separation cap which prevents separation of the motor assembly.