Westinghouse PWRs, Alloy 600 Pressurizer Projects

Challenge: Over time, using alloy 600 for welds throughout PWR plants has necessitated inspections, repairs and replacements of many components.  For example, pressurizer (PZR) welds, especially on the surge line below the PZR nozzles and on the safety and spray lines on top of the PZR, have the potential to crack and leak.

Solution: PWR owners and NPO identified the expected highest dose contributors during the proposed weld overlay operation.  Then, using a variety of shielding materials, we developed shields for the heaters, surge line nozzle and elbow, bowl, and top of the pressurizer.    

Results: In every case, which included over 90 percent of power plants in the United States, dose came in under goal; Diablo Canyon set a 7 man-rem (70 mSv) record.

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