Underwater Reaming of Reactor Centering Holes With Chip Suction
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Solution Overview
Problem
The existing methods for repairing damaged centering holes in nuclear fuel assembly end pieces are complex, risky, and costly, often requiring replacement of the entire part, which can lead to additional damage and the need for specialized storage and disposal of radioactive materials.
Innovation Solution
A repair device comprising a remotely operable cutting tool with a suction system for underwater machining of centering holes, allowing for reaming of damaged holes to restore precise dimensions without extracting the fuel assembly from the reactor, using a cutting tool with a suction channel and filtration system to manage debris.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the entire nozzle is replaced to repair a damaged centering hole, then the centering hole can be restored to original specifications, but the operation becomes time-consuming and risks damaging other parts of the assembly
Solution Approach 1:
The repair operation is segmented into distinct functional components: a separate cutting tool with suction channel, a support structure, and a drive mechanism. This allows the centering hole to be repaired in-place without removing the entire nozzle, significantly reducing repair time while maintaining precision through the specialized cutting tool design
Solution Approach 2:
A suction channel acts as an intermediary between the cutting tool and the external environment, capturing chips and coolant during the machining process. This intermediary system enables precise underwater machining by maintaining a clear cutting zone and removing debris that would otherwise interfere with the cutting operation
2Reliability
If the nozzle is replaced to repair a damaged centering hole, then the damaged part is removed, but radioactive waste handling and specialized storage are required
Solution Approach 1:
Instead of discarding the entire radioactive nozzle, the invention recovers and retains the nozzle in place by repairing only the damaged centering hole. The suction channel captures and contains radioactive chips during machining, allowing them to be controlled and managed locally rather than generating additional radioactive waste through complete part replacement
Solution Approach 2:
The repair process changes the physical state and parameters of the centering hole by removing damaged material and restoring precise dimensions through controlled machining. This transforms the damaged hole into a functional hole meeting original specifications, extending component life without requiring radioactive waste disposal procedures
3Ease of operation
If underwater machining is performed to repair the centering hole, then the fuel assembly can remain in the reactor, but chip removal and coolant management become necessary
Solution Approach 1:
The suction channel and coolant delivery system are merged into a single integrated component - the cutting tool itself. The suction channel is formed within the body of the cutting tool, combining chip removal and cooling functions in one element. This integration simplifies the overall device complexity while enabling effective underwater machining operations
Solution Approach 2:
The cutting tool with integrated suction channel serves multiple functions simultaneously: it cuts the centering hole, cools the cutting zone, and removes chips. This multi-functional design eliminates the need for separate systems for each operation, making the underwater repair process practical while maintaining ease of operation
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
Enables quick, reliable, and economical repair of centering holes, extending the life of nuclear fuel assembly components, reducing the risk of further damage and the need for radioactive waste handling, while maintaining precise machining within design limits.
Implementation Method 1
a suction channel (44) extending inside the cutting tool (22) from an inlet opening (46) provided in the cutting portion (40) to an outlet opening (48) provided in the driving portion (42)
Data Source
Figure 1
Figure 2~4
Figure 3
AI summary
The invention relates to a repair device, which includes a holder (32), a cutting tool (22) held by the holder (32) and having at least one cutting tooth (70) for re-machining an inner surface of the hole, the cutting tool (22) having a suction channel (44) extending into the cutting tool (22) between at least one inlet opening (46) and at least one outlet opening (48), a drive shaft (34) for rotating the cutting tool (22), the drive shaft (34) being held by the holder (32), and a suction tube (36) connected to the holder (32) and fluidly coupled to the outlet opening (48) of the suction channel (44).