Modular Tip Tool Guide for Steam Generator Shot Peening
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Solution Overview
Problem
In nuclear power equipment steam generators, existing shot peening methods from the inner peripheral surface of nozzle stubs face challenges such as high radiation doses, limited operator time, the need for compact and lightweight tools, and the lack of accurate and prompt peening solutions to reduce stress-corrosion cracking in nickel-chromium-iron alloy regions.
Innovation Solution
A tip tool guide apparatus comprising a swivel support portion, a slide table, and a manipulator, which can be disassembled and reassembled within the steam generator's water chamber through a narrow manhole, allowing for precise and efficient shot peening operations while minimizing operator exposure to radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shot peening is performed from the inner peripheral surface side of nozzle stubs, then stress-corrosion cracking of nickel-chromium-iron alloy regions can be reduced, but operator exposure to high radiation doses increases and operator time in water chamber is limited
Solution Approach 1:
A manipulator with a tool changer is introduced as an intermediary device to perform shot peening operations. The manipulator can be positioned outside the water chamber and extend its tool through the nozzle stub to apply shot peening to the inner peripheral surface, thereby eliminating the need for operators to enter the high-radiation water chamber while still achieving the stress-corrosion cracking reduction effect
Solution Approach 2:
The manual mechanical operation of shot peening by operators inside the water chamber is replaced with an automated manipulator system. The manipulator, controlled from outside the water chamber, performs the shot peening operation through a tool changer mechanism, substituting human mechanical action with automated mechanical systems that can operate in high-radiation environments
2Ease of operation
If a compact and lightweight tool is used for shot peening, then the tool can be brought into the water chamber through the narrow manhole, but the tool lacks the precision and versatility needed for accurate peening operations
Solution Approach 1:
The shot peening system is segmented into multiple components: a manipulator base, a tool changer mechanism, and interchangeable tip tools. This segmentation allows the system to be assembled in stages through the narrow manhole while maintaining the capability for precise positioning and accurate shot peening operations. The modular design enables the system to fit through the manhole when disassembled and be reconfigured for precision work once inside the water chamber
Solution Approach 2:
The manipulator system incorporates dynamic positioning capabilities with multiple degrees of freedom, allowing it to adjust its position and orientation precisely once installed in the water chamber. The tool changer mechanism dynamically switches between different tip tools based on the specific peening requirements, providing both accessibility through the narrow manhole and precision during operation
3Ease of manufacture
If the tip tool guide apparatus is assembled outside the water chamber, then assembly is easier, but the apparatus cannot be properly positioned and operated within the confined water chamber space
Solution Approach 1:
The tip tool guide apparatus is divided into separable components that can be assembled outside the water chamber in a controlled environment, then transported through the narrow manhole in disassembled form. Once inside the water chamber, the components are reassembled and positioned using the manipulator's positioning mechanisms, combining the advantages of easy external assembly with precise internal positioning
Solution Approach 2:
The manipulator system is pre-positioned and secured in the water chamber before the tool changer and tip tools are installed. This preliminary action creates a stable base structure that facilitates subsequent assembly steps and ensures the apparatus is properly positioned for operation before full assembly is completed
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 accurate and prompt shot peening within the steam generator, reducing residual stress in critical alloy regions and ensuring operator safety by allowing the apparatus to be assembled and operated within the water chamber, thus addressing the limitations of existing methods.
Implementation Method 1
guides various tip tools, necessary to perform shot peening, along a processing region for shot peening
Data Source
AI summary
A tip tool guide apparatus is brought into a water chamber of a steam generator of nuclear power equipment, and guides a tip tool, such as a shot peening head, along a necessary region. For this purpose, a tip tool guide apparatus 1000 is composed of a swivel support portion 100, a slide table 200, and a manipulator 300. The swivel support portion 100 is self-supported and fixed within the water chamber, and turns the slide table 200 connected thereto. The slide table 200 connects the manipulator 300, and moves the manipulator 300 slidingly in a fore-and-aft direction. The manipulator 300 grasps the tip tool at its leading end. For bringing into the water chamber, the swivel support portion 100, the slide table 200, and the manipulator 300 are separated from each other, brought in individually, and assembled within the water chamber to constitute the tip tool guide apparatus 1000.