In order to fulfil requirements for corrosion resistance for new reactor GIV, the austenitic 304L stainless steel and 18Cr-20Mn austenitic steel were improved by oxide dispersion strengthening (ODS), using two nano-oxide types: titanium and yttrium oxides.
Two new ODS steels and a reference material, A/SA-270 grade 304L SS as plate, were characterised by different techniques and its behaviour in SCWR environment was considered. Coolant compatibility studies have been performed in demineralised water at supercritical conditions: temperature of about 550°C and 25 MPa pressure. The oxide developed on the 304ODS samples is layered, thicker and more uniform than on 304L SS. Some oxides grown on 18Cr-20MnODS steel are un-adherently and they are lost in the simulated water coolant.
The weight gains of ODS samples are positive and higher than 304L SS up to approximately 1320 hours while on 18Cr-20MnODS steel is negative. The oxide films were investigated by SEM and EDS techniques.