A detailed investigation was made of historical data recorded at Experimental Breeder Reactor II during operation with superheater SU-712. The objective of this study was to analyze and characterize the performance of 72 duplex steam tubes that became unbonded during a long period of operation. The information processing system ANALYZE was developed to perform the required numerical manipulations, statistical analyses, and correlation analyses with a large data base containing some five million data values. The ANALYZE system was successfully employed (a) to characterize the performance of all the steam tubes in terms of frequency and relative serverity of unbonding, and (b) to establish a correlation between the observed anomalous behavior of the superheater and its operating parameters. Results from this investigation were used to select sections for materials examinations and physical tests that were performed after SU-712 was removed from operation.