Jet Pump Slip Joint Seal for BWR Thermal Expansion

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Solution Overview

Problem

Boiling water reactor jet pumps experience flow-induced vibrations at slip joints, leading to leakage and potential damage due to differential thermal expansion and flow through narrow passages, which existing assemblies fail to adequately address.

Innovation Solution

A sealing device is introduced, featuring a collar with guiding fins and a clamp system that securely fastens a seal between the inlet mixer and diffuser, utilizing a combination of seals and restraint features to prevent vibration and allow for thermal growth, comprising a support ring with grooves, clamp sections with fin engagement, and additional seals to ensure a strong mechanical linkage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a slip joint with narrow gap is used to accommodate differential thermal expansion, then thermal growth is allowed, but flow-induced vibrations occur leading to leakage and potential damage

Engineering Contradiction:

Improvethermal expansion accommodationVSAvoidleakage prevention

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

A seal member is introduced as an intermediary element between the first and second members at the slip joint. This seal member prevents leakage through the narrow gap while allowing the members to relatively move axially for thermal expansion accommodation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The seal member is positioned specifically at the narrow gap region of the slip joint, providing localized sealing functionality only where needed, while maintaining overall structural integrity and thermal expansion capability.

Inventive Principle:

Principle #3Local quality

2Reliability

If a seal is added to prevent leakage at the slip joint, then leakage is reduced, but the seal may be damaged by flow-induced vibrations

Engineering Contradiction:

Improveleakage preventionVSAvoidvibration damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Retention members are provided to hold the seal member in position before vibrations can cause damage. These retention members prevent the seal from being displaced or damaged by flow-induced vibrations during operation.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The retention members act as intermediary protective elements between the seal member and the harmful vibrations, absorbing or mitigating the vibrational effects before they can damage the seal.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the seal and retention features are added to the slip joint, then leakage and vibration damage are prevented, but device complexity increases

Engineering Contradiction:

Improveoverall slip joint performanceVSAvoidslip joint structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The seal member and retention members are integrated into a unified slip joint assembly where the retention members are positioned to hold the seal member in place, combining multiple functions into a coordinated structure rather than separate components.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The retention members serve multiple functions: they hold the seal member in position, prevent vibration damage, and maintain the structural integrity of the slip joint assembly, providing multi-functionality that reduces the need for additional separate components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10436227B2Sealing device for jet pump slip joints

Publication Date: 2019.10.08 FRAMATOME ANP INC

AI summary

A sealing device for a jet pump of a boiling water reactor is provided. The jet pump includes an inlet mixer and a diffuser receiving the inlet mixer at a slip joint such that an outer circumferential surface of the inlet mixer is received in an inner circumferential surface of the diffuser at the slip joint. The diffuser includes a plurality of guiding fins, each guiding fin including a radially inner surface, a radially outer surface and lateral surfaces extending radially between the inner and outer surfaces. The sealing device includes a seal configured for sealingly contacting the outer circumferential surface of the inlet mixer and a collar configured for holding the seal against the outer circumferential surface of the inlet mixer. The collar includes portions configured for being received radially between the radially inner surfaces of the guiding fins and the outer circumferential surface of the inlet mixer. The sealing device further includes a clamp configured for contacting the radially outer surfaces of the guiding fins to axially clamp the guiding fins. A method of mounting a sealing device onto a slip joint of a jet pump of a boiling water reactor is also provided.