Stress corrosion cracking of reactor internals is another major threat to the continued safe operation of nuclear power plants beyond their design lives. Stress corrosion cracking requires the combined effects of stress, corroding environment and susceptible microstructure. In collaboration with the Materials Science Dept. at Penn State, we are conducting an investigation of the stress corrosion mechanisms of Inconel X-750, under reactor conditions. Inconel X-750 is used in special reactor applications requiring great strength and hardness, such as springs and jet pump nozzles.
 
 

In this research, we will investigate the role of hydrogen in the cracking process, by conducting both slow strain rate tests (SSRT) and compact tension type experiments. Other alloys to be investigated include alloyts 718, 625 and 690. The cracking process will be conducted in autoclaves where the electrochemical potential (ECP), temperature, and conductivity will be monitored on-line, and where the hydrogen content of the water will be a parameter. Post corrosion examinations include an examination of fracture surface, hydrogen profiling with both neutron radiography and a LECO system.