The Effluent Treatment Facility (ETF) at the Hanford nuclear-waste storage site is a waste treatment facility that removes radioactive and hazardous contaminants from various sources. The facility processes substantially more dilute waste that has lower pH values than the waste found in the tank farms. The Secondary Waste Receiving Tank B (SWRT-B) at the ETF exhibited corrosion attack on the tank ceiling and upper wall during recent inspections and this paper presents the results of laboratory investigations performed to evaluate whether the in-tank additions of sulfuric acid that are made to adjust waste pH are a possible cause for the corrosion attack. Laboratory testing was conducted to evaluate the susceptibility of 304H stainless steel (UNS S30409), including in the sensitized condition to investigate microstructural differences in welded regions, to H2SO4 vapor corrosion or splash-back corrosion. The results of electrochemical testing indicate that as-received 304H showed no susceptibility to corrosion in 4% H2SO4 even when anodically polarized while sensitized 304H exhibited corrosion at open circuit conditions. A kettle test designed to simulate the addition of H2SO4 to the SWRT-B to investigate acid vapor and splash-back corrosion was unable to replicate the corrosion observed in the tank.

Subject
Acids, Weld attack, Test methods, Materials, Corrosion rate, Sulfuric acid, Acid attack, Vapors, Acidity, Sensitization, Stainless steel, Linear polarization resistance, Wastes
Keywords:
Hanford, Effluent Treatment Facility, nuclear waste, 304H stainless steel, sensitized, sulfuric acid, vapor corrosion, splash-back corrosion, electrochemical testing
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2023
Association for Materials Protection and Performance (AMPP)
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