Tube Walker for Steam Generator Inspection

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Solution Overview

Problem

Existing nuclear steam generator maintenance technologies require manual relocation of manipulators, which is time-consuming and exposes personnel to radiation, especially when inexperienced operators are involved, due to the need for manual movement across the steam generator tube bundle.

Innovation Solution

A tube walker system with hydraulically actuated locking fingers allows the manipulator to be remotely relocated in a straight line across the steam generator tube bundle, minimizing personnel support and radiation exposure by using a movable inner and outboard section that locks onto the tubes for axial movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If manual relocation of manipulator is used, then access to tubes in exclusion zones is achieved, but personnel exposure to radiation increases and time consumption increases

Engineering Contradiction:

Improveaccess to tubesVSAvoidradiation exposure

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The manipulator system performs self-relocation by automatically moving along the tube bundle using the tube walker mechanism with locking fingers that engage with tubes at predetermined positions, eliminating the need for personnel to manually relocate the manipulator and thereby reducing radiation exposure while maintaining access to all tube regions

Inventive Principle:

Principle #25Self-service

2Adaptability or versatility

If manual relocation of manipulator is used, then access to tubes in exclusion zones is achieved, but relocation time increases

Engineering Contradiction:

Improveaccess to tubesVSAvoidrelocation time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The tube walker enables automatic self-relocation of the manipulator along the tube bundle by engaging locking fingers with tubes at predetermined positions and moving to the next position without manual intervention, significantly reducing relocation time compared to manual repositioning operations

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The manipulator is pre-programmed with a sequence of predetermined positions along the tube bundle, allowing it to automatically traverse through all required locations in a planned manner, eliminating the time-consuming manual relocation process while ensuring comprehensive access to all tube regions

Inventive Principle:

Principle #10Preliminary action

3Reliability

If manually experienced personnel are used for relocating manipulator, then reliable operation is achieved, but radiation dose to personnel increases

Engineering Contradiction:

Improveoperation reliabilityVSAvoidradiation dose

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The manipulator system performs self-relocation using automated control with pre-programmed positions and automatic locking mechanisms, eliminating the need for experienced personnel to be physically present during relocation operations, thereby maintaining operational reliability while significantly reducing radiation dose to personnel

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The manual mechanical relocation process is replaced with an automated control system that uses electronic signals to control the tube walker's movement and locking mechanisms, substituting human expertise with automated systems that maintain reliability while eliminating personnel radiation exposure during relocation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution reduces the time and variability of manipulator relocation, decreases radiation dose for support personnel, and eliminates the need for manual relocation, resulting in consistent and efficient movement comparable to individual remote operation with significant radiation dose savings during reactor outages.

Implementation Method 1

Both the inner and outboard sections have groups of 4 hydraulically actuated locking fingers which engage the tubes of the steam generator tube bundle

Methodology Applied

Scientific EffectHydraulic actuation: Hydraulic Press

Data Source

PatentUS7533715B1Tube walker for examination and repair of steam generators

Publication Date: 2009.05.19 AREVA NP INC

AI summary

An improved manipulator system having a remotely actuated tube walker assembly for reciprocally moving the manipulator along a tube bundle for inspection and repair of the tubes of the tube bundle wherein the tube walker has a movable inner section and an outboard section with both sections having groups of hydraulically actuated locking fingers which are selectively engageable with the tubes of the tube bundle so that when the fingers of the outboard section are locked the fingers of the inner section are disengaged and the inner portion can be moved axially to an aligned position with new tube locations.