Development of a non-destructive inspection technique for detecting irradiation-induced microstructural changes of austenitic stainless steels by use of an EBR-II reflector
沖田 泰良 Taira OKITA 江藤 淳二 Junji ETOH 松永 嵩 Takashi MATSUNAGA 匂坂 充行 Mitsuyuki SAGISAKA 礒部 仁博 Yoshihiro ISOBE
austenitic stainless steelscarbide densificationimmersion density measurementmicrostructureneutron irradiationnon-destructive inspection techniquetransmission electron microscopeultrasonic testingvoid swelling
Time-of-flight ultrasonic measurements were conducted on a thick hexagonal block of 304 type austenitic stainless steel, which was used as a reflector in EBR-II and was irradiated to 23 ~ 33 dpa at 37 0 ~ 410 ?C. The results of ultrasonic-implied void swelling and carbide-induced densification were compared with those obtained by immersion density measurements and transmission electron microscope o bservations. The three types of measurements were found to agree rather well with each other, and the variation in evaluating swelling decreases from ~ 0.7 % to ~ 0.3 % when we incorporate the effects of carbide formation. This study confirmed that ultrasonic velocity measurement is a powerful non-destructive inspection technique to measure the average volumetric changes across a thick component.