AREVA’s innovative baffle bolt replacement technology raises the bar for the industry


AREVA’s innovative baffle bolt replacement technology raises the bar for the industry – another successful demonstration performed of our tooling capabilities and recent design enhancements.

As part of the nuclear industry’s rigorous attention to safety, nuclear plant equipment is continuously monitored and inspected, and continually repaired or upgraded where necessary. Among the safety-related components regularly inspected are stainless steel baffle bolts that secure removable liner plates around pressurized water reactor vessels. Check out NEI’s factsheet for more information.

Leveraging our global experience and innovative methods, AREVA is at the forefront of this industry initiative. We offer nuclear plant operators a “roadmap” for baffle-to-former bolt evaluation that includes risk-based modeling, award-winning inspection capabilities and extensive replacement experience – allowing plant operators to intelligently and proactively plan examination intervals, replacement patterns and outage duration – all to control costs.

Demonstrating innovation

In 2016, tooling design experts in our Component Repair & Replacement team initiated a project to refurbish and upgrade our baffle bolt replacement tooling and processes based on lessons learned from our portfolio of internals bolt replacement experience and feedback from nuclear plant operators. This spring, AREVA is performing extensive testing to ensure tooling is ready to deploy and will meet our customers’ expectations. We want to ensure that AREVA’s technology was the best in the industry.

But it’s not enough to just say what you can do – we want to ensure that nuclear plant operators are confident in our ability to meet their outage goals and reduce their plant’s risk. That’s why on March 7-10, over 16 representatives from five different U.S. utilities got to see AREVA’s baffle bolt replacement tooling in action at the AREVA Solutions Complex in Lynchburg, Va.

During this customer demonstration, our goals were to:

  • Demonstrate our tooling capabilities and design upgrades for normal and contingency operations
    • Normal bolt removal & installation
    • Broken bolt / shank removal & installation
    • Broken bolt / oversize threading & bolt installation
  • Prove our schedule savings and field-hardened tooling
  • Prove our electrical discharge machining (EDM) operations eliminate inherent foreign material exclusion (FME) risk from traditional machining operations

And the results? We showed attendees that:

  • Production rates were faster than originally advertised with normal bolt removal at 12 bolts per day vs. previous rate of 10 bolts per day using a single mast, and 24 bolts per day with a dual mast system
  • Outage schedules could be decreased
  • EDM operations eliminated FME concerns

Now AREVA is focused on further equipment testing, qualification and preparing for deployment.

During the visit, AREVA also highlighted baffle bolt inspection technology and demonstrated the benefits of its probabilistic approach to baffle bolt management – the only approach that is proven, accepted and effective in delivering optimized bolt replacement patterns, re-examination intervals, and bolt examination sampling schemes. Collectively, the visit demonstrated AREVA’s leadership in innovative solutions for baffle-to-former bolt replacement.

Where we are today

AREVA’s Component Repair & Replacement team can now offer nuclear plant operators an innovative and efficient approach to baffle bolt replacement including:

  • A 4-loop plant bolt design
  • A contingency oversized bolt design
  • Improved mast support system
  • EDM tools modified to remove lock bar and machine counterbore for lock cup in one operation
  • An impact driver to reduce number of stuck bolts and decrease removal time
  • Custom-designed and fabricated EDM swarf filtration systems
  • Successful replacement of normal bolts in <2 hours
  • Ready-to-deploy equipment

Our history: Worldwide, AREVA has replaced over 8,700 internals bolts

AREVA has been replacing reactor vessel internals bolts since the early 1980s. Our current tooling design takes advantage of our extensive database of lessons learned. Our tooling and processes are based on existing bolt replacement that has been used on over 8,700 previous applications.


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