Abstract for Corrosion/08 Effect of H2 on SCC Growth Rates of Nickel Alloys Peter L. Andresen PWSCC in Alloy 600 and Alloy 182, 132 and 82 weld metals is important because these materials are widely used in the PWR coolant system. This study is investigating the mitigation of PWSCC by adjusting the coolant hydrogen level. A peak in growth rate is observed near the Ni/NiO phase boundary, and the H2 fugacity at which this boundary exists changes with temperature. Single and multiple condition tests have been performed on various materials and at various H2 levels to characterize the effects of the growth rate peak vs. temperature and material.