SNF Interim Storage Canister Corrosion and Surface Environment Investigations (FY2020 Status Report)

Influence of Realistic, Cyclic Atmospheric Cycles on the Pitting Corrosion of Austenitic Stainless Steels

“…All salt-printed coupons were placed in RH and T chambers and exposed to the 24 h diurnal atmospheric cycle in Table I. 9,30 Briefly, the 24 h cyclic atmospheric cycle was modeled using weather data collected from an airport proximal to an ISFSI. The ISFSI selected was Arkansas Nuclear 1 located in west-central Arkansas 9 due to high average absolute humidity (AH) and large daily temperature swings.…”

“…Assuming a deposition of sea salts on the canister surfaces, deliquesced brines will progress from a MgCl 2 -rich solution to a NaCl-rich brine. 9 Recently, a realistic diurnal cycle for laboratory exposures was developed based upon z E-mail: rmkaton@sandia.gov airport weather data gathered near Arkansas Nuclear 1, an independent spent fuel storage installation (ISFSI) location. 9 A 24 h, T and RH cycle was created from these weather data with a superimposed temperature increase of 10 °C to mimic the heated SNF canister surfaces.…”

“…In the exemplar case of SNF canisters, the inservice alloys may exhibit various surface roughness due to materials processing, initial surface preparation, and weld surface refinishing. 10 The influence of surface roughness on localized corrosion and SCC has been explored by various authors for different SS compositions, 2,3,6,[11][12][13][14][15][16][17][18] but very few have explored the influence of different surface finishes in an atmospheric, cyclic environments. Typically, rougher surfaces are thought to be detrimental to localized corrosion processes, 2,3,6,9,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] characterized by a decrease in the pitting potential, decreases in the critical pitting temperature, and increasing corrosion severity.…”

“…10 The influence of surface roughness on localized corrosion and SCC has been explored by various authors for different SS compositions, 2,3,6,[11][12][13][14][15][16][17][18] but very few have explored the influence of different surface finishes in an atmospheric, cyclic environments. Typically, rougher surfaces are thought to be detrimental to localized corrosion processes, 2,3,6,9,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] characterized by a decrease in the pitting potential, decreases in the critical pitting temperature, and increasing corrosion severity. Schaller et al 10 measured surface roughness on an actual SNF dry storage canister surface revealing a wide range of surface roughness values for SNF applications.…”

“…Typically, rougher surfaces are thought to be detrimental to localized corrosion processes, 2,3,6,9,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] characterized by a decrease in the pitting potential, decreases in the critical pitting temperature, and increasing corrosion severity. Schaller et al 10 measured surface roughness on an actual SNF dry storage canister surface revealing a wide range of surface roughness values for SNF applications. As such, it is necessary to evaluate realistic surface roughness in a dynamic atmospheric environment to inform upon potential storage applications of SNF.…”