Download or read book Inhibition of Nitrate Stress Corrosion Cracking of Mild Steel in Nuclear Process Wastes written by and published by . This book was released on 1975 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Influence of Microstructure on Stress Corrosion Cracking of Mild Steel in Synthetic Caustic nitrate Nuclear Waste Solution written by Peter Gregory Sarafian and published by . This book was released on 1975 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Factors Controlling Nitrate Cracking of Mild Steel written by and published by . This book was released on 1976 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrite and hydroxide ions in alkaline nitrate nuclear waste solutions inhibit the growth of stress corrosion cracks in mild steel storage tanks. Crack growth was measured as a function of simulated waste composition. Measurements showed that a sufficient amount of nitrite and hydroxide can prevent crack growth. However, insufficient quantities of nitrite and hydroxide ions did not influence the crack growth rate or the threshold stress intensity, but extended the initiation time. The activation energy, 27 kJ/mole (6.5 kcal/mole), was the same for both crack growth and for dissolution of mild steel in 5M sodium nitrate. Straining during dissolution did not influence the rate or temperature dependence of dissolution. The temperature dependence and composition independence of crack growth rate indicate that the mechanism of nitrate stress corrosion is anodic dissolution.
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1976-05 with total page 912 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book INHIBITION OF STRESS CORROSION CRACKING OF CARBON STEEL STORAGE TANKS AT HANFORD written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The stress corrosion cracking (SCC) behavior of A537 tank steel was investigated in a series of environments designed to simulate the chemistry of legacy nuclear weapons production waste. Tests consisted of both slow strain rate tests using tensile specimens and constant load tests using compact tension specimens. Based on the tests conducted, nitrite was found to be a strong SCC inhibitor. Based on the test performed and the tank waste chemistry changes that are predicted to occur over time, the risk for SCC appears to be decreasing since the concentration of nitrate will decrease and nitrite will increase.
Download or read book Influence of Microstructure on Stress Corrosion Cracking of Mild Steel in Synthetic Caustic nitrate Nuclear Waste Solution written by and published by . This book was released on 1975 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The influence of alloy microstructure on stress corrosion cracking of mild steel in caustic-nitrate synthetic nuclear waste solutions was studied. An evaluation was made of the effect of heat treatment on a representative material (ASTM A 516 Grade 70) used in the construction of high activity radioactive waste storage tanks at Savannah River Plant. Several different microstructures were tested for susceptibility to stress corrosion cracking. Precracked fracture specimens loaded in either constant load or constant crack opening displacement were exposed to a variety of caustic-nitrate and nitrate solutions. Results were correlated with the mechanical and corrosion properties of the microstructures. Crack velocity and crack arrest stress intensity were found to be related to the yield strength of the steel microstructures. Fractographic evidence indicated pH depletion and corrosive crack tip chemistry conditions even in highly caustic solutions. Experimental results were compatible with crack growth by a strain- assisted anodic dissolution mechanism; however, hydrogen embrittlement also was considered possible. (auth).
Download or read book THE SENSITIVITY OF CARBON STEELS SUSCEPTIBILITY TO LOCALIZED CORROSION TO THE PH OF NITRATE BASED NUCLEAR WASTES written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Hanford tank reservation contains approximately 50 million gallons of liquid legacy radioactive waste from cold war weapons production, which is stored in 177 underground storage tanks. The tanks will be in use until waste processing operations are completed. The wastes tend to be high pH (over 10) and nitrate based. Under these alkaline conditions carbon steels tend to be passive and undergo relatively slow uniform corrosion. However, the presence of nitrate and other aggressive species, can lead to pitting and stress corrosion cracking. This work is a continuation of previous work that investigated the propensity of steels to suffer pitting and stress corrosion cracking in various waste simulants. The focus of this work is an investigation of the sensitivity of the steels' pitting and stress corrosion cracking susceptibility tosimulant pH. Previous work demonstrated that wastes that are high in aggressive nitrate and low in inhibitory nitrite are susceptible to localized corrosion. However, the previous work involved wastes with pH 12 or higher. The current work involves wastes with lower pH of 10 or 11. It is expected that at these lower pHs that a higher nitrite-to-nitrate ratio will be necessary to ensure tank integrity. This experimental work involved both electrochemical testing, and slow strain rate testing at either the free corrosion potential or under anodic polarization. The results of the current work will be discussed, and compared to work previously presented.
Download or read book Slow Strain Rate Testing of Carbon Steel in Solutions with High Nitrate Concentrations written by and published by . This book was released on 1997 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Processing of high-level nuclear waste for permanent disposal will cause changes to the present inhibited compositions at the Savannah River Site. Temperature and nitrate concentration may reach new high levels during salt dissolution in the carbon steel waste tanks with certain removal methods. Proper inhibitor concentrations are necessary to minimize the potential for nitrate-induced stress corrosion cracking to maintain the integrity of the waste tanks. Slow strain rate testing and potentiodynamic polarization were used to investigate whether stress corrosion cracking would initiate under bounding removal conditions. Test conditions for two carbon steels included nitrate concentrations of 5.5 and 9.7 M at a maximum temperature of 95 degrees C. The steels were found to be resistant to SCC in the more aggressive waste compositions at the present inhibitor concentrations of 0.6 M sodium hydroxide and 0.5 M sodium nitrite.
Download or read book Prediction of Stress Corrosion of Carbon Steel by Nuclear Process Liquid Waste ASTM A285 B ASTM A516 70 written by and published by . This book was released on 1976 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A laboratory test was developed to determine the relative aggressiveness of nuclear process waste on mild steel. Tensile samples were strained to fracture in synthetic waste solutions in an electrochemical cell with the sample as the anode. When total elongation in the test is less than the uniform elongation observed in air, stress, corrosion cracking is likely if the steel is exposed to equivalent solutions and temperatures in service. A response surface equation was derived that relates elongation of a mild steel (ASTM A 285-B) to the combined effect of four independent variables of the waste solution: temperature, NO3−, NO2−, and OH−. Elongation in the electrochemical tensile test, as a measure of stress corrosion cracking potential, can be predicted from the actual waste compositions to within an average of 8 percent of the measured values. The electrochemical tensile tests showed that the supernates in SRP salt receiver tanks are the least aggressive compositions, and wastes newly generated by the separations process are the most aggressive ones. Test data also verified that ASTM A 516-70 steel is superior to ASTM A 285-B. To decrease the possibility of stress corrosion cracking, limits were recommended for waste compositions, based on present results wedge-opening-loaded test results, and expected plant operating conditions. 12 fig.
Download or read book Prediction of Stress Corrosion of Carbon Steel by Nuclear Process Liquid Wastes written by and published by . This book was released on 1978 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radioactive liquid wastes are produced as a consequence of processing fuel from Savannah River Plant (SRP) production reactors. These wastes are stored in mild steel waste tanks, some of which have developed cracks from stress corrosion. A laboratory test was developed to determine the relative agressiveness of the wastes for stress corrosion cracking of mild steel. Tensile samples were strained to fracture in synthetic waste solutions in an electrochemical cell with the sample as the anode. Crack initiation is expected if total elongation of the steel in the test is less than its uniform elongation in air. Cracking would be anticipated in a plant waste tank if solution conditions were equivalent to test conditions that cause a total elongation that is less than uniform elongation. The electrochemical tensile tests showed that the supernates in salt receiver tanks at SRP have the least aggressive compositions, and wastes newly generated during fuel repocessing have the most aggressive ones. Test data also verified that ASTM A 516-70 steel used in the fabrication of the later design waste tanks is less susceptible to cracking than the ASTM A 285-B steel used in earlier designs.
Download or read book POTENTIAL FOR STRESS CORROSION CRACKING OF A537 CARBON STEEL NUCLEAR WASTE TANKS CONTAINING HIGHLY CAUSTIC SOLUTIONS written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The evaporator recycle streams of nuclear waste tanks may contain waste in a chemistry and temperature regime that exceeds the current corrosion control program, which imposes temperature limits to mitigate caustic stress corrosion cracking (CSCC). A review of the recent service history found that two of these A537 carbon steel tanks were operated in highly concentrated hydroxide solution at high temperature. Visual inspections, experimental testing, and a review of the tank service history have shown that CSCC has occurred in uncooled/un-stress relieved tanks of similar construction. Therefore, it appears that the efficacy of stress relief of welding residual stress is the primary corrosion-limiting mechanism. The objective of this experimental program is to test A537 carbon steel small scale welded U-bend specimens and large welded plates (30.48 x 30.38 x 2.54 cm) in a caustic solution with upper bound chemistry (12 M hydroxide and 1 M each of nitrate, nitrite, and aluminate) and temperature (125 C). These conditions simulate worst-case situations in these nuclear waste tanks. Both as-welded and stress-relieved specimens have been tested. No evidence of stress corrosion cracking was found in the U-bend specimens after 21 days of testing. The large plate test was completed after 12 weeks of immersion in a similar solution at 125 C except that the aluminate concentration was reduced to 0.3 M. Visual inspection of the plate revealed that stress corrosion cracking had not initiated from the machined crack tips in the weld or in the heat affected zone. NDE ultrasonic testing also confirmed subsurface cracking did not occur. Based on these results, it can be concluded that the environmental condition of these tests was unable to develop stress corrosion cracking within the test periods for the small welded U-bends and for the large plates, which were welded with an identical procedure as used in the construction of the actual nuclear waste tanks in the 1960s. The absence of evidence of stress corrosion cracking and general corrosion in the laboratory-scaled specimens indicate that this type of nuclear waste tank is not susceptible to highly caustic solutions up to 12 M hydroxide at 125 C when sufficient nitrite inhibitor is present.
Download or read book Radioactive Waste Processing and Disposal written by U.S. Nuclear Regulatory Commission and published by . This book was released on 1980 with total page 908 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Temperature Dependence of Nitrate Stress Corrosion Cracking of Mild Steel written by and published by . This book was released on 1977 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The temperature dependence of nitrate stress corrosion in mild steel is given by activation energies of 27 kJ/mol for continuous and 56 kJ/mol for discontinuous crack growth. The mechanism of nitrate stress corrosion in mild steel has been interpreted as anodic dissolution, and these results support this interpretation, except that an intergranular oxide is formed and the metal is not dissolved directly. If the stress intensity, K, increases, then the mode of crack growth is fracture of the intergranular oxide or the oxide-metal interface. Nevertheless, anodic dissolution is an inherent part of the process, but by the solid state reaction in the grain boundaries. An initiation time is required even in precracked specimens, and this observation is attributed to the time required to form intergranular oxide. The suggested controlling mechanisms are dissolution of the intergranular oxide in specimens in which k decreases with crack length and grain-boundary diffusion of oxygen in specimens in which K increases.
Download or read book A STUDY OF CORROSION AND STRESS CORROSION CRACKING OF CARBON STEEL NUCLEAR WASTE STORAGE TANKS written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Hanford reservation Tank Farms in Washington State has 177 underground storage tanks that contain approximately 50 million gallons of liquid legacy radioactive waste from cold war plutonium production. These tanks will continue to store waste until it is treated and disposed. These nuclear wastes were converted to highly alkaline pH wastes to protect the carbon steel storage tanks from corrosion. However, the carbon steel is still susceptible to localized corrosion and stress corrosion cracking. The waste chemistry varies from tank to tank, and contains various combinations of hydroxide, nitrate, nitrite, chloride, carbonate, aluminate and other species. The effect of each of these species and any synergistic effects on localized corrosion and stress corrosion cracking of carbon steel have been investigated with electrochemical polarization, slow strain rate, and crack growth rate testing. The effect of solution chemistry, pH, temperature and applied potential are all considered and their role in the corrosion behavior will be discussed.
Download or read book ERDA written by and published by . This book was released on 1976 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Report of the Activities written by United States. Congress. Joint Committee on Defense Production and published by . This book was released on 1973 with total page 1200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book INVESTIGATION OF THE POTENTIAL FOR CAUSTIC STRESS CORROSION CRACKING OF A537 CARBON STEEL NUCLEAR WASTE TANKS written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The evaporator recycle streams contain waste in a chemistry and temperature regime that may be outside of the current waste tank corrosion control program, which imposes temperature limits to mitigate caustic stress corrosion cracking (CSCC). A review of the recent service history (1998-2008) of Tanks 30 and 32 showed that these tanks were operated in highly concentrated hydroxide solution at high temperature. Visual inspections, experimental testing, and a review of the tank service history have shown that CSCC has occurred in uncooled/un-stress relieved F-Area tanks. Therefore, for the Type III/IIIA waste tanks the efficacy of the stress relief of welding residual stress is the only corrosion-limiting mechanism. The objective of this experimental program is to test carbon steel small scale welded U-bend specimens and large welded plates (12 x 12 x 1 in.) in a caustic solution with upper bound chemistry (12 M hydroxide and 1 M each of nitrate, nitrite, and aluminate) and temperature (125 C). These conditions simulate worst-case situations in Tanks 30 and 32. Both as-welded and stress-relieved specimens have been tested. No evidence of stress corrosion cracking was found in the U-bend specimens after 21 days of testing. The large plate test is currently in progress, but no cracking has been observed after 9 weeks of immersion. Based on the preliminary results, it appears that the environmental conditions of the tests are unable to develop stress corrosion cracking within the duration of these tests.
