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Jet Pump Repairs

Jet Pump Flow Control Collar Restricts Leakage & Provides Support to Mitigate Jet Pump Damage

Jet Pump Repairs

AREVA’s repair permanently addresses the largest contributor to flow-induced vibration (FIV) issues on your existing jet pump assemblies

Provides Sealing and Restraint

The BWR industry is currently facing jet pump challenges, due to leakage at the slip joint, causing instability and resulting in flow-induced vibration. By addressing this root cause, AREVA BWR experts can deliver cost-effective technology that restricts leakage, provides lateral support, and allows for thermal expansion. A new enhanced design includes ~360 degree sealing capability around the slip joint without any modifications to the existing jet pump assembly.

Addresses the Root Cause

A slip joint is needed to allow thermal growth between the jet pump assembly and the reactor vessel. Leakage through the slip joint causes flow induced vibration. The flow control collar incorporates a seal around the mixer assembly that restricts flow from the slip joint. The lower edge of the collar includes a feature that also restricts leakage to seal on the counter-bore of the diffuser assembly. Swing clamps are utilized for engaging the collar to the diffuser guide fins. These clamps provide holding force to secure the flow control collar to the diffuser. The combination of clamping forces from the seal and swing clamps provide lateral support to the slip joint assembly.

Flow Control Collar Advantages

  • The optimal solution to address the largest contributor of FIV
    — OEM aux wedges and slip joint clamps do not fix the problem
  • Minimizes potential leak paths to restrict flow
  • Provides lateral support to tie the mixer to the diffuser while allowing thermal growth
  • Simple installation without jet pump disassembly
  • No loose parts — delivered as one assembly
  • Life-of-plant repair
  • Cleanest solution available for jet pump repair
  • Additional restraint features may be included

Testing Early 2016

  • Vibration & leakage testing to validate performance
  • Applicable to ALL BWR jet pump configurations

AREVA solutions provide long-term asset protection and more efficient power output when you need it most - all from a single source.

Features & Benefits

  • Minimizes leakage
  • Provides restraint
  • Resolves all FIV issues from slip joint leakage
  • Replaces the function of the slip joint clamp
  • No modifications to jet pump
  • Installation — one shift per jet pump pair
  • Other jet pump repairs include:
    — Riser pipe repairs
    — Restrainer bracket & wedge repairs
    — Slip joint clamps
    — Set screw repairs
    — Riser brace repairs
    — Sensing line repairs
    — Auxiliary wedge repairs
    — As-built dimensions of existing jet pumps (underwater laser scanning)

AREVA’s repair permanently addresses the largest contributor to Flow-Induced Vibration (FIV)issues on your existing jet pump assemblies

As the BWR industry faces new jet pump
challenges, AREVA combines integrated
programs, processes, techniques, and tooling to deliver a permanent solution. For example, studies demonstrate that leakage at the slip joint causes instability resulting in FIV. By addressing this root cause, AREVA BWR experts can deliver cost-effective technology that restricts leakage and allows for thermal expansion. A new enhanced design includes (~360°) sealing capability around the slip joint without the need to remove the guide fins from the diffuser. Allowances have also been
incorporated that can accommodate the thermal growth differences between the diffusers and the riser pipe.

 AREVA’s Process

A slip joint is needed to allow thermal growth. Leakage through the slip joint causes FIV. The collar incorporates a metal O-ring that seals against the mixer assembly. The lower edge of the collar includes a compliant feature to seal on the counter-bore of the diffuser assembly. Swing clamps are utilized for engaging the collar to the diffuser guide fins. These clamps provide the holding force to compress the lower compliant seal. The combination of clamping forces from the O-ring and swing clamps provides lateral support to the slip joint assembly.

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Additional Information
Contact Us

Lisa Hawkins
Business Development Manager, CR&R
Tel: 434.832.2858