Metallurgical analysis and comparative nondestructive inspection results on specimens removed from a retired from service PWR steam generator

In a project sponsored by the U. S. NRC, EPRI, and consortia from France, Italy, and Japan, the Steam Generator Group Project (SGGP) is utilizing a retired from service PWR steam generator for a broad range of research. High among the program objectives is to provide validation of inservice nondestructive examination technology. This objective is being met by conducting extensive nondestructive examination (NDE) using a variety of equipment and repetitious examinations with different teams. The steam generator is subsequently being destructively sectioned to allow metallographic correlations between NDE indicated defects and those actually present. This paper presents a summary of findings at the time of authorship. Documented degradation in the generator, to date, includes stress corrosion cracking in the inner row U-bends, denting at the tube support plates and in the tube sheet crevice, wastage in the sludge pile, extensive copper deposits, loose parts due to support plate disintegration associated with the denting, and recently discovered deep pitting on the hot leg just above the tube sheet. There also is an indication, as yet unproven, of intergranular attack near the top of the tube sheet crevice