External Control Drum Controller With Wire-Pulley Drive
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Solution Overview
Problem
Nuclear reactors for nuclear thermal propulsion face challenges in reducing size and mass while maintaining safety and efficiency, particularly in remote applications where space is limited and human intervention is not feasible.
Innovation Solution
A control drum controller is positioned outside the pressure vessel, utilizing a wire-pulley system to rotate control drums, reducing mass and eliminating rotary seal penetrations, and enabling precise neutron flux control through a combination of actuators, tension members, and counterweights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If control drum actuators are positioned inside the pressure vessel, then direct control of control drums is achieved, but the pressure vessel size and mass increase
Solution Approach 1:
The actuator is extracted from the interior of the pressure vessel and repositioned on the exterior. The control drum remains inside the pressure vessel while the actuator operates outside, connected through a mechanical linkage system that transmits force without requiring internal actuator components. This extraction eliminates the need for large internal actuator housings and penetrations, reducing pressure vessel volume while maintaining control functionality.
Solution Approach 2:
A mechanical linkage system serves as an intermediary between the external actuator and the internal control drum. This intermediary mechanism transmits rotational force and motion from the external actuator to the internal control drum through shafts, gears, or direct mechanical connection, enabling control reliability without requiring the actuator to be positioned inside the pressure vessel.
2Ease of operation
If rotary seal penetrations are used to connect internal actuators to control drums, then control functionality is maintained, but device complexity and failure risk increase
Solution Approach 1:
The actuator is completely extracted from the pressure vessel interior, eliminating the need for rotary seal penetrations that would be required to connect internal actuators to control drums. The mechanical linkage system transmits force through the pressure vessel wall without requiring penetrating seals, thereby reducing device complexity and failure risk associated with seal maintenance and leakage.
3Force
If larger actuators are used to provide sufficient torque, then control drum rotation is achieved, but mass and space requirements increase
Solution Approach 1:
The actuator is repositioned from an internal to an external location, changing the spatial dimension of force application. This allows the use of a smaller, lighter actuator that operates outside the pressure vessel, with force transmitted through a mechanical linkage system to the control drum. The external positioning enables better leverage and reduced actuator size compared to internal mounting requirements.
4Ease of repair
If internal components are maintained within the pressure vessel, then direct maintenance access is possible, but safety risks and maintenance complexity increase
Solution Approach 1:
The actuator is extracted from the radiation-filled interior of the pressure vessel and positioned on the exterior. This extraction allows maintenance personnel to service the actuator outside the pressure vessel, eliminating the need to enter or disassemble the pressure vessel for maintenance. The mechanical linkage system maintains control functionality while enabling safe, external maintenance operations.
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 design allows for a smaller, more maintainable pressure vessel by eliminating internal components, improving actuator resolution, and enhancing safety through reduced torque and snap-close features during power loss.
Implementation Method 1
The control drum controller includes a counterweight that is external or internal to a control drum to impart a reverse torque on the control drum
Implementation Method 2
A control drum controller is positioned outside the pressure vessel, utilizing a wire-pulley system to rotate control drums
Data Source
AI summary
A nuclear reactor system includes a nuclear reactor core disposed in a pressure vessel. Nuclear reactor system further includes control drums disposed longitudinally within the pressure vessel and laterally surrounding fuel elements and at least one moderator element of the nuclear reactor core to control reactivity. Each of the control drums includes a reflector material and an absorber material. Nuclear reactor system further includes a control drum controller with a counterweight to impart a reverse torque on the control drum. Control drum controller includes a driven pulley coupled to the counterweight, a tension member coupled to the driven pulley to rotatably control the driven pulley and apply torque to the driven pulley, and an actuator to apply a tension force to the tension member. The actuator counteracts the reverse torque with the applied tension force, and the tension member applies the torque in response to the tension force.