Jet Pump Clamp System for Vibration Suppression

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Solution Overview

Problem

In nuclear power plants, excessive leakage flow in jet pump assemblies of boiling water reactors leads to flow-induced vibration, causing component degradation due to increased vibration levels and corresponding vibration loads, which existing technologies fail to adequately mitigate.

Innovation Solution

The implementation of a clamp system comprising first and second clamps with connectors that allow movement in specific directions while limiting or preventing movement in others, specifically designed for the jet pump assembly to maintain stiffness and suppress vibration, by engaging the inlet mixer and diffuser components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a rigid connection is used between inlet mixer and diffuser, then vibration is reduced, but thermal expansion movement is restricted causing stress accumulation

Engineering Contradiction:

Improvevibration controlVSAvoidstress concentration

Core Design Contradiction:

Stability of the object's compositionVSStrength

Solution Approach 1:

The patent employs a flexible connector comprising a hollow flexible tube that allows relative movement between the inlet mixer and diffuser while maintaining connection. This flexible element accommodates thermal expansion and contraction without creating stress concentration points, thereby preventing vibration while allowing necessary movement.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent changes the physical state and properties of the connection by using a flexible tube with specific material characteristics (elastomeric or plastic material) that can deform elastically. This parameter change allows the connection to adapt to thermal variations while maintaining structural integrity and reducing vibration.

Inventive Principle:

Principle #35Parameter changes

2Temperature

If thermal expansion clearance is increased, then thermal movement is accommodated, but leakage flow increases causing FIV

Engineering Contradiction:

Improvethermal expansion accommodationVSAvoidleakage flow induced vibration

Core Design Contradiction:

TemperatureVSObject-generated harmful factors

Solution Approach 1:

The flexible connector acts as a seal while accommodating thermal movement. The flexible tube maintains contact between the inlet mixer and diffuser throughout the thermal cycle, preventing leakage flow that would otherwise occur in rigid connections with clearance gaps, thereby eliminating FIV while allowing thermal expansion.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The flexible connector serves as an intermediary element between the inlet mixer and diffuser, mediating the interaction between thermal expansion forces and the connection structure. It transmits necessary movement while maintaining sealing, preventing direct contact that would cause vibration.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If rigid restrainer brackets are used, then system stiffness is increased, but oscillating motion in slip joint persists

Engineering Contradiction:

Improvesystem stiffnessVSAvoidslip joint oscillation

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

The flexible connector replaces rigid restrainer brackets by providing continuous flexible support that eliminates the slip joint interface. This flexible connection maintains system stiffness through material properties and geometry while preventing oscillating motion that occurs in rigid slip joint arrangements.

Inventive Principle:

Principle #30Flexible shells and thin films

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 effectively reduces oscillating motion and flow-induced vibration, maintaining the stiffness of the slip joint interface and allowing for thermal expansion, thereby preventing component degradation and enhancing the operational stability of the jet pump assembly.

Implementation Method 1

The slip joint between the inlet mixer and a collar of the diffuser may have an operating clearance that accommodates relative axial thermal-expansion movement between the upper and lower portions of the jet pump

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

it may be desirable to provide a jet pump assembly that has a lateral load in the slip joint area to maintain the stiffness of the interface between the inlet mixer and diffuser to prevent oscillating motion and suppress FIV

Methodology Applied

Scientific EffectVibration suppression: Damping

Data Source

PatentUS9589684B2Apparatuses and methods for controlling movement of components

Publication Date: 2017.03.07 GE HITACHI NUCLEAR ENERGY AMERICAS LLC

AI summary

An apparatus for controlling movement of a first component integrated with a second component may include a first clamp configured to engage the first component, a second clamp configured to engage the second component, and a plurality of connectors configured to connect the first and second clamps. The connectors may allow movement of the first clamp relative to the second clamp in a first direction between the first and second clamps. The connectors may limit movement of the first clamp relative to the second clamp in a second direction perpendicular to the first direction.