Chemistry Envelope for Pitting and Stress Corrosion Cracking Mitigation
- Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
- Private Consultant, Portland, OR (United States)
The present waste chemistry controls for the Hanford double-shell tanks (DSTs) were established in the 1980s in response to tank failures caused by stress corrosion cracking (SCC) at the DOE Savannah River Site (SRS). Portions of the SRS chemistry limits were coupled with corrosion testing results from Pacific Northwest Laboratory (PNL) and adopted for corrosion control of the DST waste at the Hanford Site. Since that time, the temperatures of many DST wastes have decreased to less than 50 °C as the radioactive material has decayed, the testing program in Argentina demonstrated that chloride ion in Hanford Site waste could cause pitting, and other work showed that dilute solutions could cause pitting at the liquid air interface (LAI). Moreover, future transfers from the single shell tanks and the waste treatment plant and process changes may shift the DST waste chemistries to a broader range of compositions with higher aggressive anion concentrations than the wastes that are presently stored. The decreasing temperatures led to the formulation of new chemistry controls for the minimization of SCC risks for operations below 50 °C in 2010, and these controls were partially adopted. The Tank Integrity Expert Panel (TIEP) Corrosion Subgroup (CSG) recommended that additional testing be performed to assess the potential for pitting and LAI corrosion. Since 2015, DNV-GL, SRNL, and the Hanford Site laboratory have investigated pitting and LAI corrosion at current and anticipated DST chemistries and Savannah River National Laboratory (SRNL) undertook a statistically based investigation of the role of nitrate and halide ion induced pitting corrosion. The objective was to develop a comprehensive waste chemistry envelope for the simultaneous minimization of the pitting and SCC risks caused by halide and nitrate ions. This report summarizes the technical basis for the new waste chemistry envelope to minimize the potential for both pitting and cracking corrosion induced by nitrate and halide ions, and the strategies used for the validation of the new controls.
- Research Organization:
- Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
- Sponsoring Organization:
- USDOE Office of Environmental Management (EM)
- DOE Contract Number:
- AC09-08SR22470
- OSTI ID:
- 1568783
- Report Number(s):
- SRNL-STI-2019-00217; TRN: US2100468
- Country of Publication:
- United States
- Language:
- English
Similar Records
Waste Chemistry Envelope for the Determination of Pitting Corrosion Susceptibility - 19554
Relationship Between the Marginal Probability of Failure for a CPP Test and the Recommended Corrosion Control Requirements for Hanford Double Shell Waste Tanks