The Development of the Corrosion Control Limits for Direct Feed Low-Activity Waste Melter-Off Gas Returns to Hanford Tank Farms - 18196
- Savannah River National Laboratory (United States)
- Washington River Protection Solutions, LLC (United States)
The Savannah River National Laboratory has been developing a corrosion model to facilitate implementation of Hanford's Direct Feed Low Waste (DFLAW) flowsheet. Laboratory testing and statistical analysis have been used to determine the necessary corrosion controls for returning effluent from the Hanford Waste Treatment and Immobilization Plant's Low Activity Waste Vitrification melter off-gas treatment system to the tank farms. The stream compositions are projected to contain components at relative concentrations that are significantly more corrosive toward carbon steel, specifically halide and sulfate anions, than the current waste compositions in the tank farms. Administrative programs are in place to mitigate potential corrosion mechanisms and thereby maintain the structural and leak integrity functions of these waste tanks throughout their intended service life. Waste chemistry and temperature control are the means by which corrosion degradation of the waste tanks is minimized. The current administrative specification for chemical composition and temperature for the underground carbon steel waste tanks is not designed to control the higher halide or sulfate composition. The content of the DFLAW waste streams will be diverse and depend on several factors, such as the melter feed composition and melter idle time. Other factors, such as effluent management of the off gas water collections, will impact the variability of the return streams even more. The work performed by the Savannah River National Laboratory has confirmed that the halide ions are the most aggressive species in the return stream compositions projected using a flowsheet simulation, and nitrite is the most effective inhibitor at pH 10 and 40 deg. C. This test program has employed statistically designed test matrices to determine the dependent variables and the interaction terms between the variables that are significant for the corrosion model and definition of the corrosion control specifications. The first phase of testing focused on identifying aggressive species in off-gas condensate return compositions that present a propensity for localized corrosion attack, namely pitting corrosion. The second phase of testing focused on developing a corrosion model from the interaction terms that will predict the susceptibility of pitting in the double shell tank system based on waste composition and the required amount of corrosion inhibitor. The data collected from this testing program in conjunction with other testing programs, both at the Savannah River Site and the Hanford Site, along with operations knowledge, has determined the chemistry ranges and chemical species requirements for corrosion control in the Hanford double-shell tank system for the effluents generated in the Hanford Waste Treatment and Immobilization Plant's Low Activity Waste facility during the DFLAW phase of operations. (authors)
- Research Organization:
- WM Symposia, Inc., PO Box 27646, 85285-7646 Tempe, AZ (United States)
- OSTI ID:
- 22975372
- Report Number(s):
- INIS-US-20-WM-18196; TRN: US21V0185015414
- Resource Relation:
- Conference: WM2018: 44. Annual Waste Management Conference, Phoenix, AZ (United States), 18-22 Mar 2018; Other Information: Country of input: France; 11 refs.; Available online at: https://www.xcdsystem.com/wmsym/2018/index.html
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANIONS
CARBON STEELS
CHEMICAL COMPOSITION
CORROSION INHIBITORS
FLOWSHEETS
GAS CONDENSATES
HALIDES
HANFORD ENGINEERING DEVELOPMENT LABORATORY
NITRITES
OFF-GAS SYSTEMS
PH VALUE
PITTING CORROSION
RADIOACTIVE WASTE FACILITIES
RADIOACTIVE WASTE PROCESSING
RADIOACTIVE WASTE STORAGE
REGRESSION ANALYSIS
SAVANNAH RIVER PLANT
SULFATES
TEMPERATURE CONTROL
VITRIFICATION