b'high-magnification image of the gapFigure 3d), which was held at 1300C ORNL SATS high- between the fuel and cladding.A fuel- for 1 min. This phenomenon was temperature oxidationcladding bond was not formed, whichnot observed for unirradiated ATF-18 testing of irradiatedis consistent with expectations for asurrogate specimens oxidized in steam C35MN FeCrAl showedlow burnup irradiation.at 1300C up to 240 min.resistance to oxidationAll in-cell tests of irradiated ATF-18Accomplishments:up to 1200C but quicklyspecimens were conducted with aThis series of SATS testing at ORNL begin to oxidize atstandard sample holder under therepresents the first time that ATF-1 1300C. same test conditions for unirradiatedrods irradiated in ATR at INL were surrogate specimens. The specimen wastested using a methodology first first ramped from room temperature toenvisioned nearly a decade ago 600C under an argon atmosphere at aand realized through sustained rate of 20C/min. Following this initialDepartment of Energy- Nuclear ramp, the argon supply was shut off,Energy (DOE-NE) investment. The steam was supplied to the test section,workflow demonstrated here has and the temperature was ramped toshown that Advanced Fuel Campaign 1200C at 7.5C/min. The sample(AFC) possesses the infrastructure was either held at 1200C or slowlyand experience to perform integral ramped to 1300C at 1.82C/min. Theirradiation testing of light water hold times and terminal temperaturesreactor (LWR) material concepts up for the in-cell tests are summarized into and including fuel safety testing. Figure 2. The results of these tests also provide The results indicate the irradiatedevidence that irradiated FeCrAl FeCrAl C35M alloy provided goodalloys exhibit oxidation behaviors thermal stability up to 1200C, thoughdissimilar from those observed in higher-magnification images revealedthe unirradiated state. This is an some cracks initiated from the outerimportant outcome that will motivate surface.At 1300C enhanced oxidationadditional research to understand the was observed on the inner surfaceperformance of this family of alloys at several areas of the ATF-18F1 (seeunder design basis accident scenarios.52 2021|AFC ACCOMPLISHMENTS'