The present most widely used alloys for tubing in steam generators and structural materials in water cooled reactors are Alloy 690 and Alloy 800.However, both alloys, while improved over Alloy 600 may not meet the needs of longer range applications in the range of 80-100 years.Alloy 690 sustains damage resulting from the formation of cavities at grain boundaries which eventually cover about 50% of the area of the grain boundaries with the remainder covering being covered with carbides.The cavities seem to nucleate on the carbides leaving the grain boundaries a structure of cavities and carbides.Such a structure will lead the Alloy 690 to fail completely.Normal Alloy 800 does not produce such cavities and probably retains a large amount of its corrosion resistance but does sustain progressive SCC at a low rate.A new alloy, 800CR, has been developed in a collaboration among Arioka, Tapping, and Staehle.This alloy is based on a Cr composition of 23.5-27% with the remainder retaining the previous Alloy 800 composition.800CR sustains a crack velocity about 100 times less than Alloy 690 and a negligible rate of initiation.The 800CR alloy is now seeking a patent.