Crevice Corrosion of Stainless Alloys in Liquid Waste Environment of the Nuclear Power Plant

The comparative capabilities of type 316L (UNS⁽¹⁾ S31603) and a duplex stainless steel (SS) and three high-nickel stainless alloys were studied for use in the waste processing plant of nuclear power stations. Exposure tests were carried out in the synthetic waste solutions of different pHs at boiling point using multiple crevice assemblies. The frequency and the depth of crevice attack were evaluated statistically. Type 316L SS and duplex SS exhibited almost an equivalent incidence of crevice corrosion. However, deep and severe attack was observed only for type 316L SS, whereas uniform and shallow attack was seen for duplex SS. The high-nickel stainless alloys showed a considerably higher crevice corrosion resistance than type 316L SS. They were immune against crevice attack in a pH 8 solution, but not in a pH 5 solution.