J. Kasl, D. Jandová, T. Vlasák, J. Hakl, O. Brenner, J. Cizner

The most promising materials for production of ADDT (Acceleration Driver Transmutation Technology) loop components for spent nuclear fuel transmutation are nickel superalloys. The excellent mechanical properties, creep resistance, corrosion resistance in an environment of fused fluoride salt and resistance against radiation embrittlement are required for these alloys. Presented work has been focused on assessment of properties of recently developed material called MoNiCr alloy in conditions after various thermo-mechanical processing. The creep behaviour and high-temperature corrosion in molten fluoride salts of two experimental nickel alloys (MoNiCr type) and a comparative alloy (Hasteloy B type) have been investigated. The most suitable technological parameters (formability and resistance against cracks) were obtained for non modified alloy MoNiCr. The creep tests were performed at temperature 700 °C in stress range from 80 to 160 MPa. The longest times to rupture were achieved for samples after forging however the dispersion of results was rather higher. A moderately better creep resistance showed alloy of Hasteloy B in comparison with alloys of MoNiCr types. The corrosion tests have been performed in a protection nitrogen/hydrogen atmosphere at a temperature of 710 °C in environment of molten mixture of NaF and LiF. The corrosion losses have been measured. Surface structure changes were observed using electron microscopy and microanalysis and corrosion mechanisms during tests were specified. The corrosion speeds of all alloys are on comparable level.

Creep and Corrosion

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