Hanford Double Shell Waste Tank Corrosion Studies - Final Report FY2015

Fuentes, Roderick E.; Wyrwas, Richard B.

doi:10.2172/1262318

Cited by 6 publications

(24 citation statements)

References 5 publications

(8 reference statements)

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“…SRNL initiated the New Limits testing in FY16 using statistical analysis to design matrices for a wide range of chemistries and to determine significant species that contribute and inhibit pitting corrosion [4]. The testing was performed using the standardized Cyclic Potentiodynamic Polarization (CPP) test developed by TIEP-CSG [3] and presented in Table 2-2.…”

Section: New Limits Pitting Corrosionmentioning

confidence: 99%

“…Testing with LDP and GW simulants for legacy carbon steel corrosion was started in FY14 with a long term immersion experiment in which the deleterious effects of these chemistries were observed, with mass loss corrosion rates obtained of approximately 10 mpy [9], [10]. During FY16 testing was focused on the inhibition strategies involving commercial VCI directly applied to the samples to mitigate VSC and other types of corrosion.…”

Section: Secondary Liner Corrosionmentioning

confidence: 99%

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Hanford Double Shell Waste Tank Corrosion Studies (Final Report FY2019)

Fuentes

Shukla

Crossland

et al. 2020

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VCIs formulations were added during mid-course of experiments, i.e., after coupons have experienced corrosion in the untreated GW simulant. Three tests were conducted using VCI-A and VCI-B. The first two tests were conducted using 100% recommended dosages of VCI-A and VCI-B. The third test was conducted at 10% of the recommended dosage of VCI-B. Following conclusions are made from the experimental data and results:  The corrosion rate data indicated that 10% of the recommended dosage is insufficient in mitigating corrosion. This observation is consistent with a prior study which also concluded that VCIs' effectiveness vanishes at 10% of the recommended dosages for the aboveground tank bottom underside application.  The data also showed that 100% recommended dosages of VCI-A and VCI-B mitigated pitting corrosion of weathered coupons. Specifically, VCI-A mitigated pitting corrosion in immersed, Level 2, and Level 3 coupons, whereas VCI-B mitigated pitting corrosion in immersed, Level 1, and Level 3 coupons. Statistical significance of corrosion rate decrease in Level 1 coupons for 100% recommended dosage of VCI-A and Level 2 coupons for 100% recommended dosage of VCI-B could not be established; this may be due to choice of coupons' surface orientation being vertical during the tests, leading to limited and uneven weathering during groundwater only and groundwater plus VCI exposures. 3. Long term OCP Drift Tests OCPs of carbon steel were measured in three simulants from the new limits testing. Two sets of coupons, with three coupons in each set, were fabricated with differing surface conditions. The coupons' surface conditions included a 600-grit polished surface, and a surface with mill-scale plus corrosion products from legacy carbon steel (rail car steel AAR TC-128). Two coupons, one coupon from each set, were placed in each chemistry, and OCPs of the coupons were monitored for five months. OCPs of the coupons with polished surfaces evolved in the anodic direction with respect to the initial values, whereas OCPs of two of the three coupons with mill-scale plus corrosion products evolved in cathodic direction with respect to the initial values. Terminal OCP of one mill-scale plus corrosion products coupon was about 100 mV anodic with respect to the initial value. CPP data of the polished coupons before OCP evolutions showed mixed responses, i.e., a clear delineation between pitting and no-pitting cannot be made, and CPP data after OCP evolutions remained mixed (category 3), indicating that change in OCP values did not affect the CPP responses. Following exposures of the coupons during OCP evolutions, CPP data for the mill-scale plus corrosion products coupons in the three simulants showed negative hysteresis (category 1), which is a sign of no-pitting. The OCP and CPP data indicate that simulant chemistry and surface condition affect extent and direction of OCP evolution, however, OCP evolution does not affect the pitting susceptibility. Electrochemical Impedance Spectroscopy (EIS) spectra of the polished coupon...

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Section: New Limits Pitting Corrosionmentioning

confidence: 99%

Section: Secondary Liner Corrosionmentioning

confidence: 99%

Hanford Double Shell Waste Tank Corrosion Studies (Final Report FY2019)

Fuentes

Shukla

Crossland

et al. 2020

View full text Add to dashboard Cite

show abstract

“…Testing with LDP and GW simulants for legacy carbon steel corrosion was started in FY14 with a long term immersion experiment in which the deleterious effects of these chemistries were observed, with mass loss corrosion rates obtained of approximately 10 mpy [7] [8]. During FY16 testing was focused on the inhibition strategies using commercial VCI to coat the samples and minimize VSC and other types of corrosion.…”

Section: Secondary Liner Corrosion Inhibitionmentioning

confidence: 99%

“…Another key difference between laboratory testing using CPP and field conditions has been the surface condition of coupons used in the laboratory testing in comparison with the field condition of the tanks. CPP tests have been conducted using the bullet coupons with 600 grit ground surfaces [4], [5], [7], [8] whereas the tanks were constructed using the steel with mill scale plus corrosion products. It is recognized that during the construction process, large sheets of the carbon-steel metal were welded together, and other processes associated with tank construction likely have disturbed the original mill-scale on portions of the tank liner.…”

Section: Anodic Drift Studiesmentioning

confidence: 99%

“…The testing initiated in FY16 used a test matrix from Plackett-Burman and Box-Behnken statistical designs. From the experiments, the significant aggressive species identified were nitrate and chloride, while significant inhibitor species were hydroxide and nitrite at specific ranges of chemistries based on tank chemistry[4]. In FY17, electrochemical experiments were expanded to include high hydroxide concentrations and additional interior points.…”

mentioning

confidence: 99%

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