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Detailed Program
Paper Number : ST-P06
Time Frame : 12:00~13:30
Presentation Date : Friday, 28, November
Session Name : Structual Ceramics & Refractory materials
Session Chair 1# : -
Session Chair 2# : -
TEM Analysis Study on the Microstructure of Oxides Formed on the Surface of FeCrAl Alloy at High Temperature
Dong Jun PARK
Korea Atomic Energy Research Institute
Keywords: FeCrAl Alloy, Oxide, TEM, Microstructure,

Recently, interest in using FeCrAl alloy as the nuclear fuel cladding material in conventional light water reactors (LWRs) has increased considerably. This is because its superior oxidation resistance at high temperatures could significantly reduce the risk of explosions caused by hydrogen gas, as was the case in the Fukushima nuclear reactor accident. Other superior properties of FeCrAl alloy are excellent formability and very good high strength at high temperature. For these reasons, Fe-based alloy is considered as one of the most promising candidates for accident tolerant fuel material.
The integrity of the fuel cladding should be maintained not only during normal operation but also in a postulated design-based accident. Therefore, it is necessary to understand clearly the oxidation behavior of candidate materials under both normal operation and loss-of-coolant accident (LOCA) condition for their application to the fuel cladding material in LWRs.
In this study, long-term corrosion and high temperature oxidation behaviors were investigated in a corrosion environment simulating pressurized water reactor and simulated LOCA condition. In the first test, the alloy was corroded in pressurized 360¡É water representing normal operation conditions for periods up to 400 days, with the aim of studying the long-term corrosion behavior of FeCrAl alloy. In the second one, alloy specimen was exposed to flowing water vapor at 1200¡É for 3000 s to simulated LOCA condition. To study high temperature oxidation behavior of FeCrAl alloy under steam environment, thermo-gravimetric analyzer was used and weight change of the samples was measured in real time. For all the specimens, the effect of oxidation environment was evaluated in terms of weight gain for unit area.
It was observed that oxides grown during the test show differences in their chemical properties and micro structure depending on their test conditions. As shown below image, Fe2O3 oxide was grown in water static test at 360¨¬C while Al2O3 layer was observed in high temperature oxidation test at 1200¨¬C. The detailed analysis study for oxide layers was carried out by using High resolution TEM, XRD, and XPS.
Acknowledgements : This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2012M2A8A5000702)