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NuVision Engineering and Westinghouse Apply MSIP® Under Emergent Conditions on a Reactor Vessel Nozzle at Seabrook

November 10, 2009

Pittsburgh, PA 

During the fall 2009 outage, NuVision and Westinghouse successfully applied MSIP® at the Seabrook Nu-clear Power Plant located in Seabrook, New Hampshire (just north of Boston).  The team along with the customer, NextEra Energy, to successfully mitigate a flaw in the reactor vessel D hot leg nozzle-to-pipe weld that was discovered during a 10 year in-service inspection.

On an emergent basis the team mobilized more than 30 people at the station and in Pittsburgh offices to complete the work in a two week time period. The implementation was supported by a variety of tasks, tool design and manufacture, flaw assessments, justification of continued operation and preparation for the application of MSIP®. The site activities were completed one day ahead of site schedule, taking 13 hours in the cavity with a team dose of 2R.

This was a first application of MSIP® to a reactor vessel nozzle located in a gallery. Because the work occurred while the plant was in Mode 5 with a fully loaded core, the team received special training that emphasized quality and efficiency during the implementation as well continuous reinforcement of safety, human performance and ALARA.

The customer had the following to say about the success of this project. “The MSIP® pro-ject on the D hot leg at Seabrook was a great success. This project was emergent and fast tracked within an outage. The key elements for the success were the professionalism of the team and its integration with the station’s team. We worked side by side to learn all we could from previous MSIP® projects, plan a unique rigging configuration and practice and gain profile on a customer built mock up and then we implemented the project per the plan.”

Stress corrosion cracking as a result of excessive tensile stress is a recognized problem which can compromise nuclear plant safety and availability. NuVision’s Mechanical Stress Improvement Process (MSIP®) is a patented process, invented and developed by NuVision Engineering, for preventing or mitigating stress corrosion cracking in operating nuclear plant pipe weldments. The process works by removing tensile residual stress and generating a favorable compressive stress pattern in its place. The success of this application builds upon NuVision’s excellent performance applying MSIP® to over 6000 welds worldwide.

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