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 Smart Engineering Systems written by Cihan H. Dagli and published by . This book was released on 1998 with total page 936 pages. Available in PDF, EPUB and Kindle. Book excerpt: Investigating a noise cancellation system for speakerphones. Reproduced from typescripts. Annotation copyrighted by Book News, Inc., Portland, OR.

Download or read book Materials Performance written by and published by . This book was released on 1999 with total page 824 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 1988 with total page 1344 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Radioactive Waste Management written by and published by . This book was released on 1981 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book DETERMINATION OF CORROSION INHIBITOR CRITERIA FOR TYPE III written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissolution of salt from Type III/IIIA waste tanks at the Savannah River Site may create solutions with inhibitor concentrations below those currently required (0.6M OH− and 1.1M OH− + NO2−) per the Corrosion Control Program for high nitrate salt solutions (5.5 to 8.5M NO3−). An experimental program was conducted to evaluate the corrosion susceptibility of grade A537 carbon steel for waste simulants containing 4.5-8.5M NaNO3 with maximum inhibitor concentrations of 0.6M NaOH and 0.2M NaNO2. These maximum inhibitor concentrations used in this program are at a reduced level from those currently required. Current requirements were initially established for the Types I, II and IV tanks made of A285 carbon steel. The experimental program involved corrosion testing to evaluate the pitting and stress corrosion stress corrosion cracking (SCC) susceptibility of the Type III/IIIA waste tank materials. The program was conducted in two phases; the results of the first phase were reported previously (WSRC-STI-2006-00029). In this second phase, the corrosion specimens were modified to represent the 'as-fabricated' condition of the tank wall, and included specimens with mill scale, ground welds and stress-relief heat treatments. The complete description of the corrosion testing and the results are reported herein. The collective corrosion test results for A537 carbon steel in high nitrate waste simulants (4.5 - 8.5M) with the maximum inhibitor concentrations of 0.6M NaOH and 0.2M NaNO2 were as follows: (1) In long-term non-polarized U-bend testing, heat treatment, similar to the waste tank stress relief regime, reduced the incidence of cracking over the 18-month test period. Vapor space SCC was found to initiate on non-heat treated U-bend coupons. (2) In polarized U-bend testing, cracking occurred on U-bend coupons that had welds prepared similar to those in the waste tanks, i.e. ground and heat treated. (3) In electrochemical testing, pitting occurred on all coupons independent of heat treatment, inhibitor concentration, temperature, surface preparation, or welding. (4) In slow strain rate testing, cracking occurred on samples tested in solutions containing up to the maximum inhibitor concentration. The primary conclusion derived from this experimental program is that A537 carbon steel exposed to high nitrate (> 5.5M) solutions at inhibitor levels below the current specifications (0.6M OH− and 1.1M OH− + NO2−) are susceptible to localized corrosion in the form of pitting and stress corrosion cracking. Long-term storage (e.g., greater than 100 days) of dissolved salt solutions not meeting the current inhibitor specifications for high nitrate salt chemistries in Type III waste tanks shall be avoided. Short term storage (e.g., less than 100 days) at low temperatures (e.g., less than 50 C) in these tanks is permissible for waste removal purposes. The stress relief process reduces the risk of SCC in the Type III waste tanks. On the other hand, the current inhibitor specifications should be strictly followed for the Type I, II and IV waste chemistry to prevent initiation of localized corrosion mechanisms. These tanks were not stress relieved and are more susceptible to SCC.

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 Radioactive High Level Waste Tank Pitting Predictions written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A series of cyclic potentiodynamic polarization tests was performed on samples of ASTM A537 carbon steel in support of a probability-based approach to evaluate the effect of chloride and sulfate on corrosion the steel's susceptibility to pitting corrosion. Testing solutions were chosen to systemically evaluate the influence of the secondary aggressive species, chloride, and sulfate, in the nitrate based, high-level wastes. The results suggest that evaluating the combined effect of all aggressive species, nitrate, chloride, and sulfate, provides a consistent response for determining corrosion susceptibility. The results of this work emphasize the importance for not only nitrate concentration limits, but also chloride and sulfate concentration limits.

Download or read book Metals Abstracts written by and published by . This book was released on 1988 with total page 1244 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book DETERMINATION OF CORROSION INHIBITOR CRITERIA FOR TYPE III IIIA TANKS DURING SALT DISSOLUTION OPERATIONS written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Preparation of high level waste for vitrification involves in part the dissolution of salt cake from the carbon steel storage tanks. The salt crystals composing this cake are high in nitrate concentration with the interstitial liquid being high in hydroxide and nitrite concentration. During the salt dissolution process, a stage is reached in which the inhibitors, hydroxide and nitrite, are insufficient to prevent nitrate stress corrosion cracking (SCC) and fall outside the requirements of the corrosion control program. Additional inhibitors, which are necessary to meet the requirements, may be counterproductive to the efficiency of the process and waste minimization. Corrosion testing was initiated to better characterize the necessary inhibitor concentration for high nitrate waste during salt dissolution processing. A four-phase test program is being conducted: (1) electrochemical characterization, (2) accelerated or polarized U-bend testing, (3) long-term (non-polarized) U-bend testing and (4) vapor space U-bend tests. Electrochemical testing, which included cyclic potentiodynamic polarization (CPP), linear polarization resistance (LPR) and open-circuit potential (OCP) measurements, was performed to identify stress corrosion cracking susceptibility, to characterize pitting resistance and to determine the general corrosion rate. Polarized U-bend tests were utilized to assess the effect of minimum inhibitor concentrations and heat treatment on SCC and to determine test parameters for future long-term U-bend testing. Results from CPP, LPR and OCP tests demonstrated that carbon steel formed a protective oxide film and the potential became electropositive during exposure to the waste at all inhibitor concentrations. The tenacity of this film improved as the inhibitor concentration level was increased and the temperature was decreased. This passive film increased the resistance to localized corrosion significantly. Therefore if any of these inhibitor levels are selected for storage of dissolved salt solutions, no changes to the service life estimates that were based on general corrosion are necessary. The breakdown potential for SCC as well as the other electrochemical parameters were independent of nitrate concentration (4.5-8.5 M). The breakdown potential, however, was strongly affected by temperature (i.e., 25 and 50 C) and inhibitor concentration. These results indicate that for this nitrate concentration range a critical inhibitor level is necessary for minimizing the occurrence of SCC. The polarized U-bend tests were in good agreement with the electrochemical tests. The U-bend testing clearly demonstrated that the heat treating of the samples clearly improved the SCC resistance of A537 carbon steel even at the low inhibitor concentration (0.01 M hydroxide and 0.01 M nitrite). This concentration was insufficient to prevent cracking for any tested nitrate concentration (4.5-8.5 M). At a 7 M nitrate concentration, SCC was prevented for inhibitor concentrations as low as 0.3 M hydroxide and 0.1 M nitrite. The current inhibitor requirements for a waste containing 7 M nitrate are 0.6 M hydroxide and 1.1 M hydroxide and nitrite. Thus, a considerable reduction in the amount of inhibitor necessary may be attained. It will also be recommended that the temperature of the dissolved salt solution be maintained below 50 C.

Download or read book PROBABILITY BASED CORROSION CONTROL FOR WASTE TANKS written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As part of an ongoing study to evaluate the discontinuity in the corrosion controls at the SRS tank farm, a study was conducted this year to assess the minimum concentrations below 1 molar nitrate, see Figure 1. Current controls on the tank farm solution chemistry are in place to prevent the initiation and propagation of pitting and stress corrosion cracking in the primary steel waste tanks. The controls are based upon a series of experiments performed with simulated solutions on materials used for construction of the tanks, namely ASTM A537 carbon steel (A537). During FY09, an experimental program was undertaken to investigate the risk associated with reducing the minimum molar nitrite concentration required to confidently inhibit pitting in dilute solutions (i.e., less than 1 molar nitrate). The experimental results and conclusions herein provide a statistical basis to quantify the probability of pitting for the tank wall exposed to various solutions with dilute concentrations of nitrate and nitrite. Understanding the probability for pitting will allow the facility to make tank-specific risk-based decisions for chemistry control. Based on previous electrochemical testing, a statistical test matrix was developed to refine and solidify the application of the statistical mixture/amount model to corrosion of A537 steel. A mixture/amount model was identified based on statistical analysis of recent and historically collected electrochemical data. This model provides a more complex relationship between the nitrate and nitrite concentrations and the probability of pitting than is represented by the model underlying the current chemistry control program, and its use may provide a technical basis for the utilization of less nitrite to inhibit pitting at concentrations below 1 molar nitrate. FY09 results fit within the mixture/amount model, and further refine the nitrate regime in which the model is applicable. The combination of visual observations and cyclic potentiodynamic polarization scans indicates a potential for significant inhibitor reductions at nitrate concentrations near 1.0 M without a significant increase in corrosion risk. The complete data sets from FY08 and FY09 testing have determined the statistical basis to confidently inhibit against pitting using nitrite inhibition with the current pH controls. Future testing will complete the spectrum of nitrate concentrations around 1 molar. These results will be combined to provide a complete spectrum for corrosion controls with a risk based component.

Download or read book CONTINUOSLY STIRRED TANK REACTOR PARAMETERS THAT AFFECT SLUDGE BATCH 6 SIMULANT PROPERTIES written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The High Level Radioactive Waste (HLW) Sludge in Savannah River Site (SRS) waste tanks was produced over a period of over 60 years by neutralizing the acidic waste produced in the F and H Separations Canyons with sodium hydroxide. The HLW slurries have been stored at free hydroxide concentrations above 1 M to minimize the corrosion of the carbon steel waste tanks. Sodium nitrite is periodically added as a corrosion inhibitor. The resulting waste has been subjected to supernate evaporation to minimize the volume of the stored waste. In addition, some of the waste tanks experienced high temperatures so some of the waste has been at elevated temperatures. Because the waste is radioactive, the waste is transforming through the decay of shorter lived radioactive species and the radiation damage that the decay releases. The goal of the Savannah River National Laboratory (SRNL) simulant development program is to develop a method to produce a sludge simulant that matches both the chemical and physical characteristics of the HLW without the time, temperature profile, chemical or radiation exposure of that of the real waste. Several different approaches have been taken historically toward preparing simulated waste slurries. All of the approaches used in the past dozen years involve some precipitation of the species using similar chemistry to that which formed the radioactive waste solids in the tank farm. All of the approaches add certain chemical species as commercially available insoluble solid compounds. The number of species introduced in this manner, however, has varied widely. All of the simulant preparation approaches make the simulated aqueous phase by adding the appropriate ratios of various sodium salts. The simulant preparation sequence generally starts with an acidic pH and ends up with a caustic pH (typically in the 10-12 range). The current method for making sludge simulant involves the use of a temperature controlled continuously stirred tank reactor (CSTR). Precipitated MnO2 is combined with metal nitrates and fed into the CSTR. The metals are precipitated by a caustic NaOH stream. The rates at which these streams are added allows for pH adjustment of the mixture. A graphical representation of this process is given in Figure 1. In using the CSTR method for developing simulant, there are various parameters that can be adjusted in order to effectuate a physical change in the resulting simulant: pH, temperature, mixing speed, and flow rate. How will changing these parameters affect the physical properties of the sludge simulant? The ability to determine which parameter affects a particular property could allow one to develop a simulant that would better match the physical characteristics of HLW sludge.

Download or read book STRESS CORROSION CRACKING SUSCEPTIBILITY OF HIGH LEVEL WASTE TANKS DURING SLUDGE MASS REDUCTION written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Aluminum is a principal element in alkaline nuclear sludge waste stored in high level waste (HLW) tanks at the Savannah River Site. The mass of sludge in a HLW tank can be reduced through the caustic leaching of aluminum, i.e. converting aluminum oxides (gibbsite) and oxide-hydroxides (boehmite) into soluble hydroxides through reaction with a hot caustic solution. The temperature limits outlined by the chemistry control program for HLW tanks to prevent caustic stress corrosion cracking (CSCC) in concentrated hydroxide solutions will potentially be exceeded during the sludge mass reduction (SMR) campaign. Corrosion testing was performed to determine the potential for CSCC under expected conditions. The experimental test program, developed based upon previous test results and expected conditions during the current SMR campaign, consisted of electrochemical and mechanical testing to determine the susceptibility of ASTM A516 carbon steel to CSCC in the relevant environment. Anodic polarization test results indicated that anodic inhibition at the temperatures and concentrations of interest for SMR is not a viable, consistent technical basis for preventing CSCC. However, the mechanical testing concluded that CSCC will not occur under conditions expected during SMR for a minimum of 35 days. In addition, the stress relief for the Type III/IIIA tanks adds a level of conservatism to the estimates. The envelope for corrosion control is recommended during the SMR campaign is shown in Table 1. The underlying assumption is that solution time-in-tank is limited to the SMR campaign. The envelope recommends nitrate/aluminate intervals for discrete intervals of hydroxide concentrations, although it is recognized that a continuous interval may be developed. The limits also sets temperature limits.

Download or read book Corrosion Models for Predictions of Performance of High level Radioactive waste Containers written by J. C. Farmer and published by . This book was released on 1991 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Techniques for Corrosion Monitoring written by and published by Elsevier. This book was released on 2008-02-01 with total page 711 pages. Available in PDF, EPUB and Kindle. Book excerpt: Corrosion monitoring techniques play a key role in efforts to combat corrosion, which can have major economic and safety implications. This important book starts with a review of corrosion fundamentals and provides a four-part comprehensive analysis of a wide range of methods for corrosion monitoring, including practical applications and case studies. The first part of the book reviews electrochemical techniques for corrosion monitoring, such as polarization techniques, potentiometric methods, electrochemical noise and harmonic analyses, galvanic sensors, differential flow through cells and multielectrode systems. A second group of chapters analyses the physical or chemical methods of corrosion monitoring. These include gravimetric, radioactive tracer, hydrogen permeation, electrical resistance and rotating cage techniques. Part II also includes a chapter on the innovative nondestructive evaluation technologies that can be used to monitor corrosion. Part III examines corrosion monitoring in special environments such as microbial systems, concrete and soil, and remote monitoring and model predictions. A final group of chapters includes various case studies covering ways in which corrosion monitoring can be applied to engine exhaust systems, cooling water systems, pipelines, equipment in chemical plants, and other real world systems. With its distinguished editor and international team of contributors, Techniques for corrosion monitoring is a valuable reference guide for engineers and scientific and technical personnel who deal with corrosion in such areas as automotive engineering, power generation, water suppliers and the petrochemical industry. Provides a comprehensive analysis of the range of techniques for corrosion monitoring Specific case studies are included to highlight the main issues A valuable reference guide for engineers, scientific and technical personnel who deal with corrosion

Download or read book Handbook of Corrosion Engineering written by Pierre Roberge and published by McGraw-Hill Prof Med/Tech. This book was released on 1999-09-30 with total page 1154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reduce the enormous economic and environmental impact of corrosion Emphasizing quantitative techniques, this guide provides you with: *Theory essential for understanding aqueous, atmospheric, and high temperature corrosion processes Corrosion resistance data for various materials Management techniques for dealing with corrosion control, including life prediction and cost analysis, information systems, and knowledge re-use Techniques for the detection, analysis, and prevention of corrosion damage, including protective coatings and cathodic protection More

Download or read book Corrosion for Everybody written by Alec Groysman and published by Springer Science & Business Media. This book was released on 2009-11-21 with total page 377 pages. Available in PDF, EPUB and Kindle. Book excerpt: People seldom enjoy corrosion. They usually perceive it as a nasty phenomenon with which they must cope. Yet many people, far from the corrosion field, come across it because of their professional duty. Lawyers, historians, doctors, architects, philosophers, artists, and archeologists, to name a few, may want or need to understand the principles of corrosion. This volume explains this important topic in a lucid, interesting, and popular form to everybody: to students and young engineers who are only beginning their studies, to scientists and engineers who have dealt with corrosion for many years, and to non-specialists involved in corrosion problems. The book uses a fresh writing style, with some new explanations relating to thermodynamics of oxidation of iron and mild steels in water, reversible and irreversible potential, solubility of oxygen in water and aqueous solutions of electrolytes, corrosion of metals in fuels, corrosion of storage tanks for fuels and their corrosion control, corrosion monitoring in practice, humanitarian aspects of corrosion science and technology (history of the evolution of knowledge about corrosion, relationships between corrosion and philosophy, corrosion and art). Many practical examples of various corrosion phenomena are given.