Reactor Metering Pipe Fixing Device for BWR Jet Pump Diffuser
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Solution Overview
Problem
The existing reactor metering pipe fixing devices in BWRs face challenges in reducing stress induced by fluid vibrations, leading to potential breakage and complicating remote repair in hot areas, which can affect reactor output and safety.
Innovation Solution
A reactor metering pipe fixing device with a C-shaped holding member and assembly that securely attaches to the cylindrical outer surface of the jet pump diffuser, using wedges to restrain the metering pipe and reduce stress from fluid vibrations, allowing for reliable fixing and operation even in narrow spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the metering pipe is welded to the diffuser to achieve secure fixation, then the pipe is firmly attached, but stress induced by fluid vibrations increases in the weld zone
Solution Approach 1:
The fixing device divides the fixation function into multiple components: a C-shaped holding member that attaches to the diffuser outer surface, and separate fixing members (clamps or bands) that secure the metering pipe. This segmentation avoids concentrating all stress in a single weld zone, as the C-shaped holder distributes attachment forces across the diffuser surface while the fixing members independently secure the pipe.
Solution Approach 2:
The C-shaped holding member acts as an intermediary between the diffuser and the metering pipe fixing mechanism. It attaches to the diffuser outer surface and provides mounting points for the fixing members, thereby mediating the connection and reducing direct stress concentration in any single location.
2Reliability
If a complex fixing device is used to reduce stress and secure the pipe, then reliability improves, but device complexity increases
Solution Approach 1:
The C-shaped holding member serves multiple functions: it attaches to the diffuser outer surface, provides structural support, and serves as a mounting platform for the fixing members. This multi-functionality reduces the need for separate components, thereby maintaining reliability while limiting complexity growth.
Solution Approach 2:
Instead of welding directly to the diffuser, the invention inverts the approach by using a C-shaped holding member that clamps onto the diffuser outer surface. This inverted fixation method achieves reliable attachment without the complexity and stress concentration of welding operations.
3Ease of manufacture
If welding is used to fix the metering pipe, then installation is simple, but repair difficulty increases due to remote location in hot area
Solution Approach 1:
The fixing system is segmented into the C-shaped holding member and separate fixing members, allowing the fixing members to be independently adjusted or replaced. This segmentation enables remote repair operations to focus on specific components rather than requiring complete disassembly or complex welding procedures in the hot area.
Solution Approach 2:
The fixing members are designed to be adjustable and self-contained, allowing operators to perform maintenance and repairs by simply loosening, adjusting, or replacing the fixing members without requiring specialized welding equipment or extensive disassembly in the remote hot area.
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 and ensures secure fixation of the metering pipe, enhancing reactor availability, reducing radiation exposure, and ensuring safe operation by stabilizing the pipe against fluid vibrations.
Implementation Method 1
a wedge (44, 45) which is movable in a radial direction of the cylindrical outer surface 18a of the jet pump diffuser 18
Data Source
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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.