Characterization of the corrosion behavior of the carbon steel liner in Hanford Site single-shell tanks

Abstract

Six safety initiatives have been identified for accelerating the resolution of waste tank safety issues and closure of unreviewed safety questions. These initiatives are key drivers for building and maintaining the momentum to correct tank farm problems. Safety Initiative 5 is to reduce safety and environmental risk from tank leaks. Item d of Safety Initiative 5 is to complete corrosion studies of single-shell tanks to determine failure mechanisms and corrosion control options to minimize further degradation by June 1994. This report has been prepared to fulfill Safety Initiative 5, Item d. The corrosion mechanisms that apply to Hanford Site single-shell tanks are stress corrosion cracking, pitting/crevice corrosion, uniform corrosion, hydrogen embrittlement, and microbiologically influenced corrosion. Accurate determination of single-shell tank failure mechanisms involves laboratory experiments using synthetic wastes to simulate the wastes in the singleshell tanks coupled with the destructive and non-destructive examination of single-shell tanks to compare the laboratory data with the actual corrosion of the tanks. The corrosion data relevant to the single-shell tanks dates back three decades, when results were obtained from in-situ corrosion coupons in a few single-shell tanks. Since that time there have been intertank transfers, evaporation, and chemical alterations of the waste. These activities have changed the character and the present composition of the waste is not well characterized.

Single shell tank sluicing history and failure frequency

“…These 13 distinct wastes have been mixed together as a result of consolidation efforts and the cascading of wastes to form 30 discrete tank groupings by specific waste chemistry [Anantatmula, 1994].…”

“…In the present corrosion specifications for double-shell tanks, the CF is maintanied below 2.5. The calculation of the CFS is based on a rough approximation of the chemistry of the primary and secondary wastes (70% and 30%, respectively) [Anantatmula, 1994]. The CFS calculated for the SSTS are shown in Tables 1 and 2. VISTA RESEARCH, INC. Single-Shell Tank Sluicing History and Failure Frequency HNF-3018, Rev.…”

A survey and description of candidate technologies to support single shell tank waste retrieval, leak detection, monitoring, and mitigation

“…The concrete shell supports the surface loads and the internal hydrostatic and hydrodynamic loads (WHC 1993 (Anantatmula et al 1994). SCC preferentially attacks the welds that join the steel plates of the liner because the welds were not stress-relieved.…”

Effects of hydrogen on carbon steels at the Multi-Function Waste Tank Facility

“…a Cold-work significantly increases the solubility of hydrogen. In the Anantatmula et al (1994) have noted that cyanide can assist in promoting hydrogen damage in reducing alkaline environments in the presence of sulfide. the ferricyanide complex and there is no reported sulfide.…”

“…For these reasons, the concentration o f corrosion-produced hydrogen at the steel surface i s expected to be small. Anantatmula et al (1994) have pointed out that there is no quantitative way to determine the role of potential on the effective pressure (concentration) of the hydrogen at the surface. Subramanyan (1981) shows, however, that in the worst-case kinetics, a fast discharge of the H ' and a slow combination into H, which will promote hydrogen entry into the steel, the equation is identical to the Nernst Equation found in MacInnes (1939).…”