Study of the deactivation mechanisms for some constructional steels by secondary-ion mass spectrometry

Conclusions

Dense corrosion layers on steels 48TS, 2Kh13, and 12Kh18N10T obtained under conditions simulating the first loop in a boron-regulated reactor are depleted in the alloying elements at the surface. Treatment with boric permanganate (pH∼7.4) leads to selective dissolution of the iron and partial dissolution of the iron-rich surface layer of the model oxide. Triloncitrate recipes dissolve the oxide layers efficiently when these are enriched in iron but are ineffective in dissolving chromium-bearing oxide layers.

Because of these features, the performance in removing model oxide by treatment with these transformable deactivating recipes decreases in the series 48TS, 2Kh13, and 12Kh18N10T. Therefore, a basic problem in devising effective method of deactivating constructions containing low-alloy, stainless, and chromium steels is the prevision in the deactivating solution of conditions favoring relatively uniform dissolution of the oxides of iron (nickel) and the oxides of chromium. None of the recipes considered above satisfies this requirement. Further research is in hand on the possibility of realizing these conditions.