CHARACTERISTICS OF OXIDE FILMS FORMED ON 309L AND 308L STAINLESS STEELS IN SIMULATED PWR PRIMARY WATER

摘要

The oxide films formed on 309L and 308Lstainless steel (SS) cladding in simulatedpressurized water reactor (PWR) primary waterat 325°C for 168 h and 1860 h werecharacterized. The oxide films formed on 309L SSand 308L SS showed the duplex structure with theCr-enriched inner layer, the Fe-enriched outerlayer and relatively high Ni-content at the O/Minterface. The inner oxide layer on 308L SS had ahigher Cr content and a thinner thickness thanthat on 309L SS. Cr-content in the inner oxidelayer and Ni-content at the O/M interfacedecreased with increasing immersion time from168 h to 1860 h. Pits on 309L SS after immersionfor 168 h or 1860 h. are larger than those on308L SS.The preferential oxidation of ferritephase during the immersion period of 168 hcontributes to the observed higher Cr-content inthe inner oxide layer on 308L SS than on 309LSS. The oxidation of both ferrite and austenitecontributed to the prolonged oxidation up to 1680h, leading to a decreased Cr-content in the inneroxide layer.