Study on corrosion of stainless steel in boiling nitric acid under heat transfer conditions

Ueno, Fumiyoshi  ; Shiraishi, Hironori; Inoue, Shun; Motooka, Takafumi; Kato, Chiaki   ; Yamamoto, Masahiro ; Uchiyama, Gunzo ; Nojima, Yasuo*; Fujine, Sachio*

In PUREX process for spent fuel reprocessing plants, heating portions in the components are severely corroded in the boiling solution under heat transfer (HT) conditions. In this paper, authors have focused on the effects of surface temperature and heat flux on corrosion rates (CRs) of stainless steels in boiling nitric acid under HT conditions. Two types of cells for HT and immersion conditions were applied for corrosion tests. Test solution used was 33 mol/m vanadium added to 3 kmol/m nitric acid solution, and was heated at boiling temperature under atmospheric pressure. Additionally, a boiling curve which was indicated the relation between heat flux and degree of superheating was investigated experimentally. Surface temperatures during corrosion tests were estimated from a boiling curve. The results showed that CR did not depend on heat flux, but depended on surface temperature. Arrhenius plots on CRs indicated that CR was accelerated by solution boiling against non-boiling.