Consideration of steel corrosion rates from the MASCA / METCOR-tests to the RPV strength under IVR conditions

Physicochemical interaction of prototypic UO2-ZrO2-Zr corium melt and VVER vessel steel was examined during the 2nd Phase of the ISTC METCOR Project. Rasplav-3 test facility was used for conducting four tests, in which the Zr oxidation degree and interaction front temperature were varied; in one of the tests, stainless steel was added to the melt.
Direct experimental measurements and posttest analyses were used for determining corrosion kinetics and maximum corrosion depth, as well as the steel temperature conditions during the interaction, and finally the structure and composition of crystallized ingots, including the interaction zone. The minimum temperature on the interaction front boundary, which determined its final position and maximum corrosion depth was ~1090°С. An empirical correlation for calculation of corrosion kinetics has been derived.
In this presentation the impact of the so called "corrosion" is compared to calculations without a consideration of the corrosion. The evaluated scenario considers the In-Vessel-Retention for a VVER-1000 with a stratified melt pool and with a homogeneous melt pool.