Helium Flow Stop Assembly for TIG Weld Chamber Sealing

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Solution Overview

Problem

In nuclear power generating systems, the constant open plunger in seal weld chamber assemblies leads to helium leakage, resulting in wastage of this costly and scarce resource, while also compromising the sterility of the welding environment by allowing ambient atmosphere to enter.

Innovation Solution

A helium flow stop assembly (HFSA) is introduced, which includes a housing, a sealing assembly with an arm assembly and actuator, and a seal that can engage the plunger to prevent helium from escaping and ambient atmosphere from entering the welding chamber, allowing the helium flow to be halted when not in use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the plunger is kept open for positioning end plugs, then the welding chamber remains accessible, but helium leaks and ambient atmosphere enters the chamber

Engineering Contradiction:

Improveplunger accessibilityVSAvoidhelium leakage

Core Design Contradiction:

Ease of operationVSLoss of substance

Solution Approach 1:

A seal is positioned at the plunger opening in advance, ready to engage when the plunger moves. This preliminary positioning of the sealing element prevents helium leakage and ambient atmosphere entry as soon as the plunger begins its positioning action, eliminating the need to keep the plunger permanently open.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A seal acts as an intermediary element between the plunger opening and the welding chamber interior. This seal mediates the interaction by allowing the plunger to perform its positioning function while simultaneously blocking the path for helium leakage and ambient contamination.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the plunger remains open for continuous operation, then fuel rods can be continuously positioned, but helium is constantly lost and sterility is compromised

Engineering Contradiction:

Improvecontinuous operation capabilityVSAvoidambient atmosphere contamination

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The plunger operates periodically rather than remaining continuously open. It opens only when needed to position a fuel rod end plug, then closes with the seal engaged to prevent helium loss and contamination. This periodic opening and closing maintains productivity while eliminating continuous harmful effects.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The harmful function of the open plunger (helium leakage and contamination) is extracted and separated from the useful function (positioning end plugs). The seal is introduced to specifically address and eliminate the harmful effects while preserving the positioning capability.

Inventive Principle:

Principle #2Taking out (Extraction)

3Loss of substance

If a seal is added to the plunger to prevent helium loss, then helium conservation is improved, but the device complexity increases

Engineering Contradiction:

Improvehelium conservationVSAvoidsealing mechanism complexity

Core Design Contradiction:

Loss of substanceVSDevice complexity

Solution Approach 1:

A flexible seal element is used to close the plunger opening. This thin film or shell structure provides effective sealing with minimal complexity, conforming to the plunger opening geometry and requiring simple actuation to engage and disengage.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The seal is designed to be self-actuating through the natural movement of the plunger itself. As the plunger moves to position the end plug, the seal automatically engages or disengages without requiring additional complex control mechanisms, allowing the system to seal itself during normal operation.

Inventive Principle:

Principle #25Self-service

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

The HFSA effectively reduces helium consumption by sealing the plunger, preserving the sterility of the welding environment and minimizing helium wastage, while being easily mountable and removable for use with multiple seal weld chamber assemblies.

Implementation Method 1

a plunger fluidically coupled to the welding chamber

Methodology Applied

Scientific EffectFluidic coupling:

Implementation Method 2

A helium source is configured to supply helium to the welding chamber

Methodology Applied

Scientific EffectGas flow:

Implementation Method 3

The HFSA is configured to prevent helium from escaping the welding chamber through the plunger

Methodology Applied

Scientific EffectSealing:

Data Source

PatentUS11521760B1Helium flow stop assembly (HFSA) for TIG welding process of nuclear fuel rods

Publication Date: 2022.12.06 WESTINGHOUSE ELECTRIC CORP

AI summary

An assembly configured to seal an end plug on a plugged end of a fuel tube is disclosed. The assembly includes a seal weld chamber assembly and a helium flow stop assembly (HFSA) removably coupled to the seal weld chamber assembly. The seal weld chamber assembly includes a welding chamber and a plunger fluidically coupled to the welding chamber. A helium source is configured to supply helium to the welding chamber. The end plug of the fuel tube is positionable within the welding chamber via the plunger. The HFSA is configured to prevent helium from escaping the welding chamber through the plunger.