Download or read book Inhibition of Pitting Corrosion in Simulated Liquid Radioactive Waste written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Review of Corrosion Inhibition in High Level Radioactive Waste Tanks in the DOE Complex written by and published by . This book was released on 2004 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radioactive waste is stored in underground storage tanks at the Department of Energy (DOE) Savannah River Site (SRS). The waste tanks store supernatant liquid salts, consisting primarily of sodium nitrate, sodium nitrite, sodium hydroxide, and sludge. An assessment of the potential degradation mechanisms of the high level waste (HLW) tanks determined that nitrate- induced pitting corrosion and stress corrosion cracking were the two most significant degradation mechanisms. Controls on the solution chemistry (minimum nitrite and hydroxide concentrations) are in place to prevent the initiation and propagation of pitting and stress corrosion cracking in the tanks. These controls are based upon a series of experiments performed using simulated solutions on materials used for construction of the tanks. The technical bases and evolution of these controls is presented.

Download or read book Inhibiting Pitting Corrosion in Carbon Steel Exposed to Dilute Radioactive Waste Slurries written by and published by . This book was released on 1991 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dilute caustic high-level radioactive waste slurries can induce pitting corrosion in carbon steel. Cyclic potentiodynamic polarization tests were conducted in simulated and actual waste solutions to determine minimum concentrations of sodium nitrate which inhibit pitting in ASTM A537 class 1 steel exposed to these solutions. Susceptibility to pitting was assessed through microscopic inspection of specimens and inspection of polarization scans. Long-term coupon immersion tests were conducted to verify the nitrite concentrations established by the cyclic potentiodynamic polarization tests. The minimum effective nitrite concentration is expressed as a function of the waste nitrate concentration and temperature.

Download or read book Laboratory Testing to Simulate Vapor Space Corrosion in Radioactive Waste Storage Tanks written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Radioactive liquid waste has been stored in underground carbon steel tanks for nearly 70 years at the Hanford nuclear facility. Vapor space corrosion of the tank walls has emerged as an ongoing challenge to overcome in maintaining the structural integrity of these tanks. The interaction between corrosive and inhibitor species in condensates/supernates on the tank wall above the liquid level, and their interaction with vapor phase constituents as the liquid evaporates from the tank wall influences the formation of corrosion products and the corrosion of the carbon steel. An effort is underway to gain an understanding of the mechanism of vapor space corrosion. Localized corrosion, in the form of pitting, is of particular interest in the vapor space. CPP testing was utilized to determine the susceptibility of the steel in a simulated vapor space environment. The tests also investigated the impact of ammonia gas in the vapor space area on the corrosion of the steel. Vapor space coupon tests were also performed to investigate the evolution of the corrosion products during longer term exposures. These tests were also conducted at vapor space ammonia levels of 50 and 550 ppm NH3 (0.005, and 0.055 vol.%) in air. Ammonia was shown to mitigate vapor space corrosion.

Download or read book Predictive Models for the Determination of Pitting Corrosion Versus Inhibitor Concentrations and Temperature for Radioactive Sludge in Carbon Steel Waste Tanks written by and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Statistical models have been developed to predict the occurrence of pitting corrosion in carbon steel waste storage tanks exposed to radioactive nuclear waste. The levels of nitrite concentrations necessary to inhibit pitting at various temperatures and nitrate concentrations were experimentally determined via electrochemical polarization and coupon immersion corrosion tests. Models for the pitting behavior were developed based on various statistical analyses of the experimental data. Feed-forward Artificial Neural Network (ANN) models, trained using the Back-Propagation of Error Algorithm, more accurately predicted conditions at which pitting occurred than the logistic regression models developed using the same data.

Download or read book Corrosion of Steel in Simulated Nuclear Waste Solutions written by and published by . This book was released on 1993 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: Processing of inhibited nuclear waste to forms for long-term storage will cause waste tank environments to have dynamic conditions. During processing compositional changes in the waste may produce a corrosive environment for the plain carbon steel tanks. Large concentrations of nitrates which corrode steel are contained in the waste. Nitrite and hydroxides are added to inhibit any corrosion. Concentration changes of nitrate and nitrite were investigated to identify corrosion regimes that may occur during processing. Corrosion testing was performed with cyclic potentiodynamic polarization and linear polarization resistance. Test samples were plain carbon steel which was similar to the material of construction of the waste tanks. The corrosion morphology of test samples was investigated by visual evaluation and scanning electron microscopy. Qualitative chemical analysis was also performed using energy dispersive spectroscopy. The corrosion mechanism changed as a function of the nitrate concentration. As the nitrate concentration was increased the steel transitioned from a passive state to general attack, and finally pitting and crevice corrosion. The nitrate anion appeared to destabilize the surface oxide. Nitrite countered the oxide breakdown, although the exact mechanism was not determined.

Download or read book Electrochemical Noise Measurement for Corrosion Applications written by Jeffery R. Kearns and published by ASTM International. This book was released on 1996 with total page 483 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synergistic Inhibitors for Dilute High Level Radioactive Waste written by and published by . This book was released on 1995 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cyclic potentiodynamic polarization scans were conducted to determine the effectiveness of various combinations of anodic inhibitors in the prevention of pitting in carbon steel exposed to dilute radioactive waste. Chromate, molybdate, and phosphate were investigated as replacements for nitrite, whose effective concentrations are incompatible with the waste vitrification process. The polarization scans were performed in non-radioactive waste simulants. Their results showed that acceptable combinations of phosphate with chromate and phosphate with molybdate effectively prevented pitting corrosion. Chromate with molybdate could not replace nitrite.

Download or read book LIQUID AIR INTERFACE CORROSION TESTING FOR FY2010 written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study was undertaken to investigate the corrosivity to carbon steel of the liquid-air interface of dilute simulated radioactive waste solutions. Open-circuit potentials were measured on ASTM A537 carbon steel specimens located slightly above, at, and below the liquid-air interface of simulated waste solutions. The 0.12-inch-diameter specimens used in the study were sized to respond to the assumed distinctive chemical environment of the liquid-air interface, where localized corrosion in poorly inhibited solutions may frequently be observed. The practical inhibition of such localized corrosion in liquid radioactive waste storage tanks is based on empirical testing and a model of a liquid-air interface environment that is made more corrosive than the underlying bulk liquid due to chemical changes brought about by absorbed atmospheric carbon dioxide. The chemical changes were assumed to create a more corrosive open-circuit potential in carbon in contact with the liquid-air interface. Arrays of 4 small specimens spaced about 0.3 in. apart were partially immersed so that one specimen contacted the top of the meniscus of the test solution. Two specimens contacted the bulk liquid below the meniscus and one specimen was positioned in the vapor space above the meniscus. Measurements were carried out for up to 16 hours to ensure steady-state had been obtained. The results showed that there was no significant difference in open-circuit potentials between the meniscus-contact specimens and the bulk-liquid-contact specimens. With the measurement technique employed, no difference was detected between the electrochemical conditions of the meniscus versus the bulk liquid. Stable open-circuit potentials were measured on the specimen located in the vapor space above the meniscus, showing that there existed an electrochemical connection through a thin film of solution extending up from the meniscus. This observation supports the Hobbs-Wallace model of the development of the pitting susceptibility of carbon steel in alkaline solutions.

Download or read book Radioactive Waste Management written by and published by . This book was released on 1981 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanism of Pitting Corrosion Prevention by Nitrite in Carbon Steel Exposed to Dilute Salt Solutions written by and published by . This book was released on 2002 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research has developed a broad fundamental understanding of the inhibition action of nitrite ions in preventing nitrate pitting corrosion of carbon steel tanks containing high-level radioactive waste. This fundamental understanding can be applied to specific situations during waste removal for permanent disposition and waste tank closure to ensure that the tanks are maintained safely. The results of the research provide the insight necessary to develop solutions that prevent further degradation.

Download or read book Stochastic Modeling of the Influence of Environment on Pitting Corrosion Damage of Radioactive waste Containers written by and published by . This book was released on 1994 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: A physically-based, phenomenological stochastic model for pit initiation and growth is presented as a potential tool for predicting the degradation of high-level radioactive-waste containers by aqueous pitting corrosion. Included in the model are simple phenomenological equations describing the dependence of the controlling stochastic parameters on the applied (or corrosion) potential, chloride ion concentration, and absolute temperature. Results from this model are presented that demonstrate its ability to simulate several important environmental effects on pitting.

Download or read book Reprocessing of Irradiated Fission Reactor Fuel and Breeding Materials written by and published by . This book was released on 1958 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Localized Corrosion written by Fumio Hine and published by . This book was released on 1988 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1994-11 with total page 486 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of Cooling Coil Corrosion in Storage Tanks for Radioactive Waste written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The high frequency of cooling coil leaks observed in high-heat waste storage tanks soon after sludge removal operations is attributed to pitting, according to laboratory corrosion studies. Experiments show that the most likely series of events leading to coil leakage is (1) excessive dilution of basic nitrite in the supernate, (2) initiation of attack in crevices due to oxygen depletion cells, and (3) acceleration of the attack by sulfate dissolved from the sludge. When sludge was slurried with water, the interstitial liquid was diluted. Nitrite, the anodic inhibitor that prevented attack on coils and tanks in normal operation when its concentration was 0.5 to 3.0M, could accelerate attack when diluted to 10−4 to 10−3M. Attack was presumably initiated at oxygen depletion cells. The presence of sulfate, leached from the sludge, produced a conductive solution that could produce high current densities at the corroding steel surface. The proposed series of events leading to coil leakage agrees with the observations previously made on one leaking coil removed from Tank 2F after sludge removal in 1967. Examination revealed pitting that had originated on the outside of the coils. This pitting was attributed to oxygen depletion cells in coil crevices. To prevent recurrence of pitting attack on cooling coils during future sludge removal operations, the sludge should be slurried (1) with waste diluted less than one hundredfold with water, or (2) with a 500-ppm nitrite-H2O solution at pH 12. Either method should preclude pitting damage to the coils.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.