Reactor Metering Pipe Clamp Structure for Vibration Stress Relief
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Solution Overview
Problem
The reactor metering pipes in boiling-water reactors experience high stress due to fluid vibrations, leading to potential breakage and difficulties in remote repair, which can affect the reactor's output control and require lengthy, complex repair processes.
Innovation Solution
A reactor metering pipe fixing device that securely attaches the metering pipe to the cylindrical outer surface of the jet pump diffuser using a combination of outer and inner holding members, wedges, and movable supporting mechanisms to reduce stress induced by fluid vibrations and facilitate repair access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the metering pipe is left unfixed or loosely fixed, then the repair process is simpler and faster, but the pipe experiences high stress from fluid vibrations leading to breakage and safety issues
Solution Approach 1:
The fixing device is divided into multiple independent components: outer holding members that contact the pipe externally, inner holding members that contact the pipe internally, and wedges that provide mechanical interlocking. This segmentation allows each component to perform its specific function while collectively achieving stable pipe fixation without requiring a monolithic complex structure
Solution Approach 2:
The inner holding members are positioned inside the metering pipe while outer holding members are positioned outside, creating a nested configuration where the pipe itself becomes part of the fixing structure. This nesting approach utilizes the pipe's own geometry to simplify the overall device design while maintaining reliability
2Strength
If a simple fixing method is used, then the device complexity is reduced, but the stress reduction effect on the pipe is insufficient
Solution Approach 1:
The fixing device applies localized contact forces at specific positions along the pipe through outer and inner holding members. The wedges are positioned to create localized mechanical interlocking zones that precisely counteract vibration-induced stresses. This localized approach provides effective stress resistance without requiring complex mechanisms throughout the entire pipe structure
Solution Approach 2:
The device combines multiple fixing functions into a single integrated system: the outer holding members provide external support, the inner holding members provide internal support, and the wedges provide mechanical interlocking. This merging of functions achieves comprehensive stress resistance while avoiding the need for multiple separate complex devices
3Ease of operation
If the pipe is fixed in remote and hot areas, then operational safety is improved, but the repair and installation process becomes more difficult
Solution Approach 1:
The fixing device is designed to be pre-assembled or pre-positioned above the reactor core area, allowing installation and repair work to be conducted in more accessible locations. The device's modular structure enables preliminary preparation in controlled environments before deployment to remote hot areas, reducing worker exposure to radiation and heat while ensuring proper installation
Solution Approach 2:
The fixing device acts as an intermediary structure that can be manipulated and adjusted from accessible positions. The outer and inner holding members provide contact points that can be engaged and adjusted using tools extended from outside the reactor vessel, allowing operators to work from safer, more accessible positions while still achieving secure pipe fixation in remote areas
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 device effectively reduces stress on the metering pipes, enables quick and safe repair, and improves the availability of nuclear power plants by minimizing radiation exposure and ensuring the reactor's soundness.
Implementation Method 1
wedges (44, 45, 74, 79) each wedged into a space between the inner holding member (42, 43, 76, 77) and the cylindrical outer surface (18a)
Data Source
AI summary
A reactor metering pipe fixing device fixes a reactor metering pipe disposed in a reactor to a cylindrical outer surface of a jet pump diffuser and reduces stress that may be induced in a weld zone in the reactor metering pipe. An outer holding member 41 is held on the cylindrical outer surface 18a of a jet pump diffuser 18 by a C-shaped holding member 30. The reactor metering pipe 19 is clamped from radial directions by the outer holding member 41 and inner holding members 42 and 43. Wedges 44 and 45 are wedged into a gap between the cylindrical outer surface 18a and the inner holding member 42 and a gap between the cylindrical outer surface 18a and the inner holding member 43 to fix the reactor metering pipe 19 firmly to the cylindrical outer surface 18a.