Historical views on stress corrosion cracking of nickel-based alloys: The coriou effect

This is a story about Henri Coriou of the Commissariat à l'Énergie Atomique and his work to understand alloys to be used in the primary and secondary sides of pressurized water-cooled nuclear reactors. His work started with showing that the alloy common at the time, Inconel (alloy 600), was not suitable for use despite the popular view that this was the right material. He was opposed by the International Nickel Company (INCO) and their colleagues. By 1968 their opposition withered, and the community accepted Coriou's findings, which he had organized a very substantial program to support. INCO organized a program that was weak technically and of little merit. At the same time, Coriou developed Alloy 800, a greatly superior alloy. Despite Coriou's strong and valid opposition, reactor programs of France, the United States, and Japan selected Inconel for its material for tubing in steam generators; too late, they found that Coriou was indeed correct, and that all of the world's steam generators would need to have their tubes replaced at an aggregate cost of about US$50. billion. Coriou is indeed a modern hero.