Constant Extension Rate Testing of Alloy 690 in Supercritical Water

Participants: G. S. Was, PI; S. Teysseyre, Assistant Research Scientist
SponsorElectric Power Research Institute (EPRI)

Stress corrosion cracking susceptibility of Alloy 690 has been assessed by crack growth rate tests at temperatures just below and above the critical limit of water in an effort to obtain accelerated test data and to assess the likelihood of SCC occurring in primary water conditions. Results have produced IGSCC in alloy 690 and slow but stable crack growth rates (recent unpublished data by Jacko and Andresen). Constant extension rate experiments on a different heat of alloy 690 in 400°C pure SCW containing less than 10 ppb O2 produced IGSCC, indicating a susceptibility to crack initiation under these conditions [Was, 12th Env. Deg.]. A set of CERT experiments are proposed to 1) determine the SCW conditions under which alloy 690 is susceptible to IGSCC in SCW, 2) whether the cracking depends on water density, 3) whether it is the same as that in subcritical water, and possibly 4) whether hydrogen additions can affect cracking.