May 18, 2012- San Jose, CA, USA – Aquilex WSI, LLC (WSI) and Structural Integrity Associates (SI)(together as W(SI)2) announce the recent successful installation of full structural weld overlays on three steam generator hot leg nozzles at Dominion Virginia Power’s North Anna Power Station Unit 1. North Anna is a two-unit site located in Mineral, Virginia with three-loop, Westinghouse-designed PWRs. North Anna 1 is the only PWR in the U.S. with Alloy 82/182 (600) dissimilar welds joining the low alloy steel steam generator nozzles to the stainless steel primary piping.
Dominion Virginia Power prepared the area for work, including insulation removal and scaffolding erection, and conducted pre-weld overlay examinations of the Alloy 600 welds. The W(SI)2 scope of work consisted of design and analysis, repair licensing, mockup testing and qualification, on-site implementation and post-mitigation NDE UT of the weld overlays. Although W(SI)2 has performed hundreds of weld overlays at both domestic and foreign nuclear sites in its history, the North Anna project involved the largest Alloy 600 nozzle weld yet (41” OD) to be mitigated with weld overlay. Due to the thickness of the dissimilar metal weld, approximately 20% of base material thickness was removed prior to installing the overlay for UT inspection purposes. Through this preparatory machining, the project uncovered and repaired two through-wall cracks in one of the nozzle welds. In spite of this complication, all safety, schedule, quality and dose expectations for the project were satisfactorily completed.
“This first-of-a-kind achievement was the result of more than a year-long team effort between WSI, Structural Integrity, and our Dominion Virginia Power client,” said Doug Jacobs, Senior Vice President of Aquilex WSI Nuclear. “This successful project result was the culmination of a rigorous planning and development process and incorporation of lessons learned from previous large-bore weld overlay projects.”
About Structural Integrity Associates, Inc.
Structural Integrity Associates, Inc. is an internationally recognized leader in the prevention and control of structural and mechanical failures, with a strong presence in the power generation industry. With headquarters in San Jose, CA, Structural Integrity serves clients worldwide through branch offices located throughout the US and Canada, as well as through affiliates located in China, Japan, Korea, and Spain. Structural Integrity’s expertise encompasses a broad range of issues critical to the success of fossil-fired and nuclear power plants, and oil and gas pipelines.
About Aquilex WSI Nuclear Services
Aquilex WSI Nuclear Services is a leader in the overhaul and restoration of primary, secondary and balance of plant mechanical components at nuclear facilities throughout the world. Unusual value is created by implementing engineered design solutions with advanced automatic, remotely controlled tooling and delivery systems covering a variety of functions including in-service inspections, sophisticated repairs, welding overlay and precision machining. Our highly trained and seasoned field craft are critical to the successful delivery of value to our customers.