STRESS CORROSION CRACK INITIATION MEASUREMENTS OF ALLOY 600 IN PWR PRIMARY WATER

摘要

Alloy 600 and alloy 182 are both still in use in existing PWR pressure boundary structures such as CRDM tubes, instrumentation tubes, and their welds. Understanding their stress corrosion crack (SCC) initiation response has been an area of increased interest due to new efforts to extend the life of reactors with these materials. There is also interest in understanding the difference in SCC initiation response among alloy 600, alloy 690 and their weld metals. Under the DOE-NE Light Water Sustainability Program (LWRS), PNNL has been performing SCC initiation tests on several different heats of alloy 600, including one heat removed from PWR service. Current results are presented that describe the developing relationship between SCC initiation time and the level of cold work. Crack lengths associated with initiation response are reviewed and compared to the concept of a critical stress intensity for SCC initiation. Results from alloy 600 SCC crack growth rate tests at low stress intensity are used to aid in this assessment.