Boiling Water Reactor Chimney Tube Segmentation
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Solution Overview
Problem
Conventional natural circulation boiling water reactors face challenges with stress concentration at welded edges due to flow-induced vibration, leading to potential stress corrosion cracking and complex maintenance processes due to the heavy, integrally welded flow path partition walls.
Innovation Solution
The reactor design incorporates a chimney with multiple tubes that partition the coolant flow path above the core, reducing the number of welded portions and allowing for individual detachment of tubes, thereby minimizing stress concentration and simplifying maintenance and inspection processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If flow path partition walls are integrally formed by welding plate members, then the chimney structure is rigid and stable, but the number of welded portions increases leading to stress concentration and potential stress corrosion cracking
Solution Approach 1:
The chimney is divided into multiple independent tubular members instead of being formed by welded plate grids. Each tube is a separate component that partitions the coolant flow path, eliminating the need for extensive welding at corner intersections and reducing stress concentration points while maintaining structural stability
2Strength
If flow path partition walls are integrally formed by welding, then the chimney maintains structural integrity, but removal and replacement requires great stress and time
Solution Approach 1:
The chimney structure is segmented into multiple independent tubular members that can be removed and replaced individually. Each tube can be detached without requiring the removal of the entire chimney structure, significantly reducing maintenance time and effort while maintaining structural integrity during operation
Solution Approach 2:
The modular tube design allows individual tubes to be discarded (removed) and replaced independently when needed for maintenance or repair, without requiring the removal or replacement of the entire chimney structure, thereby facilitating easier recovery and reuse of functional components
3Stability of the object's composition
If the chimney is taken out as a single unit for maintenance, then structural integrity is maintained, but handling becomes extremely complicated
Solution Approach 1:
The chimney is designed as an assembly of independent tubular members that can be handled and replaced individually. This segmentation allows maintenance personnel to work with smaller, more manageable components rather than the entire heavy chimney structure, greatly simplifying handling operations while maintaining the integrity of the remaining structure
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 reduces the risk of stress corrosion cracking, decreases manufacturing costs, and facilitates easier maintenance and inspection by allowing individual removal and replacement of tubes, enhancing the overall handling and operational efficiency of the reactor.
Implementation Method 1
a chimney is disposed above the core inside the reactor pressure vessel... The chimney has a function for promoting natural circulation of the coolant in the reactor pressure vessel by introducing the coolant which is two-phase flow including gas and liquid and is exhausted from a core
Implementation Method 2
the coolant which is two-phase flow including gas and liquid and is exhausted from a core
Data Source
AI summary
A natural circulation boiling water reactor provides to a chimney with a plurality of tubes. That is to say, each of the plurality of tubes partitions the coolant flow path above a core. Thus, unlike the conventional natural circulation boiling water reactor providing the flow path partition wall grid in which the plate members are made integral by welding and coolant flow paths are partitioned, the chimney of the natural circulation boiling water reactor can reduce the number of welded portions because the edges of the four corners of each flow path do not need to be welded. The natural circulation boiling water reactor can avoid removal as a single unit, as in the case of the flow path partition wall grid in the conventional natural circulation boiling water reactor, by detaching each tube. The chimney can be easily detached from the reactor pressure vessel.