Fatigue testing of Fort St. Vrain core outlet thermometer penetration internal attachment welds

PCRV cooling system heat load and temperature data collected during the Fort St. Vrain Hot Flow Test and rise to 2 percent power revealed that the junction of the core outlet thermometer penetrations and the cavity liner would experience a localized elevated temperature condition at full power operation. A comprehensive structural evaluation of this condition was performed, which included a detailed stress analysis of the steel penetration/liner junction and internal attachment welds. Specimens which simulated critical welds in the vicinity of the core outlet thermometer penetrations were tested under stress levels and conditions far in excess of those anticipated in actual service. The number of cycles to specimen failure or termination of the tests in all cases exceeded the specified plant operating cycles, multiplied by a factor required by the Code, by a large margin. 6 references