Heavy-Section Steel Technology Program

Three-dimensional photoelastic studies of nozzle corner cracks were initiated to obtain data on previously analyzed and tested HSST intermediate vessel geometries. Data continued to be taken on fatigue crack growth of pressure vessel steels in water reactor environment that substantiated the nonconservatism in certain related ASME Section XI Code rules. The specimens in the first 4T-CT irradiations program were tested, and a second 4T-CT program to irradiate weld metal was initiated. A study of the utilization of small specimens in irradiation effects determinations was initiated. The thermal shock facility was modified to operate on methanol--water mixtures, and three tests were performed on the 21-in.-OD specimens. An in-service half-bead weld repair was made in intermediate vessel V-7A, the vessel was flawed in a new location, and a sustained load test was successfully performed. Plans for conducting crack arrest experiments on small steel pressure vessel models were completed prior to specifying a run-arrest test on a thick-wall intermediate pressure vessel. Reheat cracks were detected in intermediate vessel V-4 consistent with early examinations that were performed in Germany by the MPA. 6 figures, 1 table