Concentric Lower Coolant Inlet Tubes for Debris Capture
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Solution Overview
Problem
Current fuel assemblies in nuclear reactors lack a natural sink for small debris particles, which can cause defects and require costly and time-consuming replacement of fuel rods, as existing debris filters are ineffective in capturing particles smaller than a certain size.
Innovation Solution
Incorporating an elongated tube with an inlet pipe that creates a local sub-pressure zone within the tube, allowing small debris particles to be caught and sink to the bottom, preventing them from causing further damage, and optionally using magnets to attract magnetic debris.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If debris filters are used to catch debris particles, then larger debris particles can be captured, but smaller debris particles still circulate indefinitely and cause damage
Solution Approach 1:
The inlet pipe is divided into two functional sections: an upper section that directs coolant flow and a lower section that forms a sub-pressure zone. This segmentation allows the system to simultaneously achieve effective debris capture and prevent damage from small particles through differentiated functional zones within the inlet structure.
Solution Approach 2:
The sub-pressure zone created by the inlet pipe acts as an intermediary mechanism between the coolant flow and debris particles. This intermediate pressure zone captures small debris particles that would otherwise circulate indefinitely, preventing them from reaching and damaging other components while maintaining coolant flow efficiency.
2Reliability
If fuel rods are replaced when defects occur, then reactor operation can be maintained, but the process is time-consuming and expensive
Solution Approach 1:
The inlet pipe structure creates a sub-pressure zone that proactively captures small debris particles before they can cause defects in fuel rods or other components. This preliminary action prevents the need for time-consuming replacement operations by eliminating the root cause of debris-related failures before they occur.
3Reliability
If the inlet pipe outlet end is positioned close to the bottom, then debris capture efficiency is improved, but coolant flow may be restricted
Solution Approach 1:
The inlet pipe is designed with different characteristics at different locations: the outlet end is positioned close to the bottom to create effective debris capture, while the upper section maintains adequate coolant flow. This local differentiation of structural characteristics allows simultaneous optimization of debris capture efficiency and coolant flow productivity.
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
Effectively captures small debris particles, preventing damage to fuel assemblies and other reactor components, reducing the likelihood of defects and the need for costly replacements.
Implementation Method 1
the inlet pipe has an inlet end and an outlet end, that the outlet end is located inside the internal passage at a distance from the bottom, thereby forming a space in the internal passage between the outlet end and the bottom
Implementation Method 2
debris particles, in particular small debris particles, which are brought by the coolant into the internal passage, may in an efficient manner be caught in the space immediately above the bottom of the elongated tube
Implementation Method 3
optionally using magnets to attract magnetic debris
Data Source
AI summary
A fuel assembly for a nuclear reactor having an upstream minor portion defining an upstream end, a main portion, and a downstream minor portion defining a downstream end. Fuel rods extend in a flow interspace permitting a flow of coolant through the fuel assembly in contact with the fuel rods. Two elongated tubes form a respective internal passage extending in parallel with the fuel rods and enclosing a stream of the coolant. Each elongated tube having a bottom, an inlet at the upstream minor portion and an outlet at the downstream minor portion. Each elongated tube having an inlet pipe having an inlet end and an outlet end in the internal passage at a distance from the bottom, thereby forming a space in the internal passage between the outlet end and the bottom.