Reactor Flow Distribution Device with Segmented Plates
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Solution Overview
Problem
Existing flow distribution devices in pressurized water reactors suffer from poor coolant distribution uniformity, increased flow resistance, and maintenance challenges due to deformation and complex installation methods, leading to reduced cooling performance and operational lifespan.
Innovation Solution
A basin-shaped flow distribution device comprising a distribution annular plate and a distribution bottom plate mounted on the lower core support plate, with reinforcing columns and threaded connections to enhance rigidity and ease of maintenance, reducing pressure loss and deformation under coolant impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an orifice plate is used as the flow distribution device, then the structure is simple, but the coolant distribution uniformity is poor and the device deforms under coolant impact
Solution Approach 1:
The flow distribution device is segmented into multiple functional components: a flow distribution plate with distributed holes, support columns for structural reinforcement, and a lower core support plate. This segmentation allows each component to perform its specific function while collectively achieving both structural simplicity and reliable coolant distribution.
Solution Approach 2:
The device uses a composite structure combining flat plate elements with cylindrical support columns. The support columns act as reinforcement ribs that prevent deformation under coolant impact while maintaining the overall simple plate structure for easy manufacturing.
2Reliability
If a flow skirt is welded on the pressure vessel inner wall, then the coolant is forced to flow through holes in the flow skirt, but the flow skirt is difficult and complex to maintain and replace
Solution Approach 1:
The flow distribution device is extracted from the pressure vessel wall and placed on the lower core support plate instead. This allows the device to be independently installed, inspected, and replaced without cutting or welding operations on the pressure vessel, significantly simplifying maintenance and replacement procedures.
Solution Approach 2:
The lower core support plate serves as an intermediary platform that supports the flow distribution device. This intermediary structure enables easy installation and removal of the flow distribution device while maintaining its functional effectiveness in distributing coolant.
3Reliability
If the flow skirt is directly welded on the pressure vessel, then the coolant can be distributed, but the flow skirt may be damaged due to different expansion coefficients
Solution Approach 1:
The flow distribution device is extracted from direct welding on the pressure vessel and repositioned on the lower core support plate. This eliminates the thermal expansion coefficient mismatch problem between the flow skirt and pressure vessel, preventing damage while maintaining coolant distribution function.
4Shape
If the annular channel is narrowed from top to bottom, then the coolant flow path is defined, but the flow resistance is increased and pressure drop is increased
Solution Approach 1:
The flow distribution plate is segmented with multiple holes of different sizes and distributions. This segmentation allows coolant to flow through multiple parallel paths rather than a single narrowed annular channel, reducing flow resistance and pressure drop while still achieving proper flow distribution into the core.
5Shape
If a narrow and long passage is formed between the flow distribution plate and pressure vessel bottom, then the coolant flows through the passage, but vortex is generated and other parts cannot be disposed in the passage
Solution Approach 1:
The flow distribution device is extracted from the narrow passage configuration and repositioned on the lower core support plate. This eliminates the vortex generation problem in narrow passages and creates sufficient space for additional components like support columns and lower internals, while maintaining effective coolant distribution.
Data Source
AI summary
A flow distribution device (3) for a reactor, a lower internals (100) of a reactor and a reactor are provided. The lower internals (100) includes: a lower core support plate (2) defining a coolant hole therethrough; a flow distribution device (3) mounted on the lower core support plate (2) and including a distribution annular plate (8) and a distribution bottom plate (9); a vortex suppression plate (7) disposed below the distribution bottom plate (9); a support column (4) defining an upper end connected with the lower core support plate (2) and a lower end passing through the distribution bottom plate (9) to connect with the vortex suppression plate (7); an energy absorption device (5) defining an upper end connected with the vortex suppression plate (7); and an anti-break bottom plate (6) disposed on the lower end of the energy absorption device (5).