A groundbreaking project at Ringhals Nuclear Power Plant has set a new benchmark for reactor internals maintenance, marking the industry's first successful deployment of Westinghouse’s next-generation clevis bolt replacement solution.
Westinghouse Electric Company, in partnership with Ringhals and Vattenfall, has successfully completed the nuclear industry’s first clevis bolt replacement using an enhanced one piece “donut” bolt design featuring integrated crimping technology.
The milestone demonstrates the viability of a next-generation approach to reactor internals bolting while establishing a new standard for safety, reliability, and outage execution performance.
The project is particularly notable because Ringhals elected to replace 100% of the unit’s clevis bolts, becoming the first nuclear unit in the world to complete a full clevis bolt replacement campaign. The decision reflects strong customer confidence in both the technical solution and the long-term value it provides for continued plant operation.
Advancing Reliability Through Innovative Design
The newly installed donut bolt incorporates advanced materials and design enhancements specifically developed to improve resistance to Primary Water Stress Corrosion Cracking (PWSCC), one of the key degradation mechanisms affecting reactor internals bolting over long-term operation.
In addition to enhanced material performance, the design includes an innovative axial retention feature that helps maintain structural integrity even in the highly unlikely event of separation between the bolt head and shank. This additional defense-in-depth capability further strengthens the safety and reliability of reactor internals components.
“The successful completion of this first-of-a-kind project demonstrates how Westinghouse’s innovation and proven engineering can be combined to address long-term fleet challenges from our customers, while maintaining the highest standards of nuclear safety and quality,” said Xavier Coll, Westinghouse President, Outage Services.
Building on Proven Technology
The clevis bolt replacement solution leverages Westinghouse’s extensive experience with its globally deployed Baffle Bolt Replacement technology, adapting proven methods, tooling, and operational practices for a new application.
This approach enabled a simplified installation process while reducing execution risk through the use of established equipment and highly experienced field personnel. Significant synergies with existing baffle bolt replacement operations, including common tooling, infrastructure, and specialized crews, contributed to efficient project delivery and cost-effectiveness.
Installation was carried out using a computer-controlled tooling system, ensuring precision, repeatability, and complete data traceability while meeting the nuclear industry's most demanding quality standards.
Collaboration Drives Success
A defining characteristic of the project was the close collaboration between Westinghouse and the Ringhals/Vattenfall organization.
During execution, a significant number of bolts exhibited resistance beyond planned untorquing values. Rather than impacting project objectives, the challenge became an example of collaborative problem-solving. Westinghouse and Vattenfall teams worked side-by-side to rapidly adapt the replacement strategy, designing, manufacturing, and deploying site-specific tooling solutions that successfully addressed actual field conditions while maintaining schedule performance.
The project was conducted with a high degree of transparency, trust, and teamwork throughout all phases of planning and execution. Customer feedback highlighted strong satisfaction with both the technical results and the collaborative approach adopted by the project teams.
Setting the Standard for the Future
The Ringhals clevis bolt replacement project represents a major industry milestone and technological leap forward. By combining innovative bolt technology, proven Westinghouse replacement methods, precision-engineered tooling, and a strong customer partnership, the project has established a new benchmark for reactor internals maintenance.
Completed safely, ahead of schedule, and with strong customer satisfaction, this first-of-a-kind deployment demonstrates the value of innovation backed by operational excellence. Most importantly, it creates a solid foundation for future clevis bolt replacement projects, paving the way for even greater efficiencies and long-term reliability improvements across the global nuclear industry.
