34 Matching Results

Search Results

Advanced search parameters have been applied.

Intergranular crack propagation rates in sensitized Type 304 stainless steel in an oxygenated water environment

Description: Intergranular stress-corrosion crack (IGSCC) propagation rates were measured in three heats of sensitized Type 304 stainless steel (SS) as a function of applied load and sensitization in high-purity water with 8 ppM. Active-loading tests yielded IGSCC propagation rates ranging from approx. 2 x 10/sup -10/ to 1 x 10/sup -9/ m/s (approx. 2 x 10/sup -5/ to 2 x 10/sup -4/ in./h) over the range of stress intensities from 25 to 46 MPa..sqrt..m (22 to 41 ksi..sqrt..in.). If the dependence of propagation rate on stress intensity is assumed to follow a power law, a least-squares fit of data yields (da/dt) = 1.23 x 10/sup -8/ K/sup 2/ /sup 42/ (in./h) for K in ksi..sqrt..in. Deflection-controlled tests on standard 12.7-mm-thick compact tension specimens yielded IGSCC propagation rates from 7 x 10/sup -12/ to 2 x 10/sup -10/ m/s (10/sup -6/ to 2 x 10/sup -5/ in./h) at effective average stress intensities in the range 21 to 26 MPa..sqrt..m (19 to 24 ksi..sqrt..in.). Crack lengths were determined by compilance measurements using in-situ high-temperature clip gage or LVDT methods, optical metallography on the side faces of the specimen, and fractography of the cracked surface after completion of the tests. The optical metallography measurements did not provide useful estimates of crack lengths, because large variations in IGSCC propagation across the thickness of the specimens occurred. The effects of the degree of sensitization on the IGSCC propagation rate are obscured by the data scatter. However, it seems clear that these variables do not lead to order-of-magnitude changes in the crack propagation rate.
Date: December 1, 1983
Creator: Park, J.Y. & Shack, W.J.
Partner: UNT Libraries Government Documents Department

Intergranular Crack Propagation Rates in Sensitized Type 304 Stainless Steel in an Oxygenated Water Environment

Description: Intergranular stress-corrosion crack (IGSCC) propagation rates were measured in three heats of sensitized Type 304 stainless steel (SS) as a function of sensitization in an environment of high-purity water with 8 ppm oxygen, using a fracture mechanics approach. Specimens were sensitized using controlled furnace heat treatments and the degree of sensitization was measured by the electrochemical potentiokinetic reactivation (EPR) method. Active loading tests were performed on standard specimens over a range of intensities. Crack lengths were determined by compilance measurements using in-situ high-temperature clip gage or LVDT methods, optical metallography on the side faces of the specimen, and fractography of the cracked surface after completion of the tests. The optical metallography measurements did not provide useful estimates of crack lengths, because large variations in IGSCC propagation across the thickness of the specimens occurred. The effects of the degree of sensitization on the IGSCC propagation rate are obscured by the data scatter. However, it seems clear that these variables do not lead to order-of-magnitude changes in the crack propagation rate.
Date: December 1, 1983
Creator: Park, J. Y. & Shack, W. J.
Partner: UNT Libraries Government Documents Department

Examination of overlay pipe weldments removed from the Hatch-2 reactor

Description: Laboratory ultrasonic examination (UT), dye penetrant examination (PT), metallography, and sensitization measurements were performed on Type 304 stainless steel overlay pipe weldments from the Hatch-2 BWR to determine the effectiveness of UT through overlays and the effects of the overlays on crack propagation in the weldments. Little correlation was observed between the results of earlier in-service ultrasonic inspection and the results of PT and destructive examination. Considerable difficulty was encountered in correctly detecting the presence of cracks by UT in the laboratory. Blunting of the crack tip by the weld overlay was observed, but there was no evidence of tearing or throughwall extension of the crack beyond the blunted region.
Date: February 1, 1985
Creator: Park, J.Y.; Kupperman, D.S. & Shack, W.J.
Partner: UNT Libraries Government Documents Department

Scanning Auger electron spectroscopy studies of grain-boundary segregation in Type 304 stainless steel

Description: Scanning Auger electron spectroscopy studies have been conducted on grain-boundary surfaces of Type 304 stainless steel that were fractured in situ. To enhance the probability of intergranular fracture, the specimens were first subjected to creep deformation for 1000 h at 700/sup 0/C. A semiquantitative surface chemical composition was calculated from the peak heights of Auger electron spectra. The concentration of Cr at the fracture surface was not different from the bulk value. This indicates that the long-term heat treatment caused healing of the sensitization. The concentrations of S, C, and Si at the fracture surface were at least an order of magnitude higher than the bulk values. Chemical composition profiles obtained by ion-sputtering indicated that segregation of S, C, P, and Si occurred within a depth of several atomic monolayers from the grain-boundary surface. Mo, Mn and Cu were not detected. The concentrations of Ni and Fe are in good agreement with the bulk chemical analysis.
Date: January 1, 1978
Creator: Park, J.Y.; Danyluk, S. & Busch, D.E.
Partner: UNT Libraries Government Documents Department

Advancing the Frontiers in Nanocatalysis, Biointerfaces, and Renewable Energy Conversion by Innovations of Surface Techniques

Description: The challenge of chemistry in the 21st century is to achieve 100% selectivity of the desired product molecule in multipath reactions ('green chemistry') and develop renewable energy based processes. Surface chemistry and catalysis play key roles in this enterprise. Development of in situ surface techniques such as high-pressure scanning tunneling microscopy, sum frequency generation (SFG) vibrational spectroscopy, time-resolved Fourier transform infrared methods, and ambient pressure X-ray photoelectron spectroscopy enabled the rapid advancement of three fields: nanocatalysts, biointerfaces, and renewable energy conversion chemistry. In materials nanoscience, synthetic methods have been developed to produce monodisperse metal and oxide nanoparticles (NPs) in the 0.8-10 nm range with controlled shape, oxidation states, and composition; these NPs can be used as selective catalysts since chemical selectivity appears to be dependent on all of these experimental parameters. New spectroscopic and microscopic techniques have been developed that operate under reaction conditions and reveal the dynamic change of molecular structure of catalysts and adsorbed molecules as the reactions proceed with changes in reaction intermediates, catalyst composition, and oxidation states. SFG vibrational spectroscopy detects amino acids, peptides, and proteins adsorbed at hydrophobic and hydrophilic interfaces and monitors the change of surface structure and interactions with coadsorbed water. Exothermic reactions and photons generate hot electrons in metal NPs that may be utilized in chemical energy conversion. The photosplitting of water and carbon dioxide, an important research direction in renewable energy conversion, is discussed.
Date: July 23, 2009
Creator: Somorjai, G.A.; Frei, H. & Park, J.Y.
Partner: UNT Libraries Government Documents Department

Crack growth behavior of candidate waste container materials in simulated underground water

Description: Fracture-mechanics crack growth tests were conducted on 25.4-mm-thick compact tension specimens of Types 304L and 316L Stainless steel and Incoloy 825 at 93{degrees}C and 1 atmosphere of pressure in simulated J-13 well water, which is representative of the groundwater at the Yucca Mountain site in Nevada that is proposed for a high-level nuclear waste repository. Crack growth rates were measured under various load conditions: load ratios of 0.2--1.0, frequencies of 2 {times} 10{sup {minus}4}{minus}1 Hz, rise times of 1--5000 s, and peak stress intensities of 25--40 MPa{center_dot}m{sup {1/2}}. The measured crack growthrates are bounded by the predicted rates from the current ASME Section 11 correlation for fatigue crack growth rates of austenitic stainless steel in air. Environmentally accelerated crack growth was not evident in any of the three materials under the test conditions investigated.
Date: December 31, 1992
Creator: Park, J.Y.; Shack, W.J. & Diercks, D.R.
Partner: UNT Libraries Government Documents Department

Computer-aided analysis of eddy current rotating probe data.

Description: Eddy current (EC) estimate of flaw size obtained from inservice inspection is often the primary means of assessing the structural integrity of steam generator tubes. Reliable prediction of failure pressure and leak rate in tubes with complex cracking requires more detailed information about the geometry and extent of degradation than is generally available from conventional bobbin coil examinations. High-resolution inspections with EC rotating probes are thus carried out on selected regions of tubing to provide the more extensive nondestructive evaluation (NDE) information that is needed to better assess flaw size and distribution. Interpretation of signals from complex cracking that are often distorted by coherent and incoherent noise can be a challenging NDE task. Studies at Argonne National Laboratory have demonstrated that computer-aided data analysis can be used for more accurate and efficient processing of the large amounts of data collected by such probes. The basic structure of a rule-based multiparameter data analysis algorithm is described in this paper. Multiple-frequency inspection data from a standard rotating pancake coil were used for the analyses. The codes were implemented as MATLAB scripts and provide, as the final outcome, profiles of flaw depth in a section of tube. Graphical user interface tools were devised to read the information needed to carry out various stages of data processing. These interactive tools allow conversion, calibration, analysis, and display of data in various formats. Representative cases of estimated flaw profiles are shown for tube specimens with laboratory-grown cracks (with and without simulated artifacts) that were used to assess sizing accuracy. The statistical analyses used to determine NDE performance are also discussed briefly. Results of investigations to date suggest that improved resolution and sizing accuracy can be obtained in a fraction of the time required for manual analysis.
Date: March 7, 2002
Creator: Bakhtiari, S.; Park, J. Y.; Kupperman, D. S. & Shack, W. J.
Partner: UNT Libraries Government Documents Department

Analysis and testing of rupture of steam generator tubing with flaws.

Description: A high-temperature (300 C), high-pressure (18 MPa), and high-leak rate (1500 L/min) facility, and a room temperature, high-pressure (52 MPa) test facility were used to test flawed steam generator tubes. Single and multiple rectangular flaws were fabricated by electro-discharge machining on the outside surface of the tubes. This paper briefly reviews analytical methods for predicting ligament rupture and unstable burst of tubes with single and multiple rectangular flaws. Test data are presented to validate the failure models. The ligament rupture pressure of specimens with multiple flaws predicted by an equivalent rectangular crack method agree fairly well with measured data.
Date: February 8, 2001
Creator: Majumdar, S.; Kasza, K. S.; Park, J. Y. & Hanna, J. A.
Partner: UNT Libraries Government Documents Department

Prediction of failure pressure and leak rate of stress corrosion.

Description: An ''equivalent rectangular crack'' approach was employed to predict rupture pressures and leak rates through laboratory generated stress corrosion cracks and steam generator tubes removed from the McGuire Nuclear Station. Specimen flaws were sized by post-test fractography in addition to a pre-test advanced eddy current technique. The predicted and observed test data on rupture and leak rate are compared. In general, the test failure pressures and leak rates are closer to those predicted on the basis of fractography than on nondestructive evaluation (NDE). However, the predictions based on NDE results are encouraging, particularly because they have the potential to determine a more detailed geometry of ligamented cracks, from which failure pressure and leak rate can be more accurately predicted. One test specimen displayed a time-dependent increase of leak rate under constant pressure.
Date: June 24, 2002
Creator: Majumdar, S.; Kasza, K.; Park, J. Y. & Bakhtiari, S.
Partner: UNT Libraries Government Documents Department

Validation of failure and leak rate correlations for stress corrosion cracks in steam generator tubes.

Description: This report summarizes models for the prediction of failure pressures and leak rates under normal operation and design-basis accident conditions in steam generator tubes with axial and circumferential cracks. These models were first validated through failure and leak rate tests at room temperature and at 282 C on tubes with rectangular, triangular, and trapezoidal notches fabricated by electrodischarge machining. They were then compared with failure and leak rate tests conducted on tubes with laboratory-generated outer-diameter stress corrosion cracks and steam generator tubes with field-induced stress corrosion cracks, which have highly complex morphology. Complex crack profiles are addressed using a model based on the concept of equivalent rectangular cracks. The predictions of the models are in reasonable agreement with test results, the time-dependent initiation and increase of leak rates observed in some tests cannot be predicted by the model.
Date: April 12, 2002
Creator: Majumdar, S.; Bakhtiari, S.; Kasza, K. & Park, J. Y.
Partner: UNT Libraries Government Documents Department

Environmentally assisted cracking in light water reactors

Description: Research during the past year focused on (1) stress corrosion cracking (SCC) of austentitic stainless steels (SS), (2) fatigue of Type 316NG SS, and (3) SCC of ferritic steels used in reactor piping, pressure vessels, and steam generators. Stress corrosion cracking studies on austentitic SS explored the critical strains required for crack initiation, the effects of crevice conditions on SCC susceptibility, heat-to-heat variations in SCC susceptibility of Type 316NG and modified Type 347 SS, the effect of heat treatment on the susceptibility of Type 347 SS, threshold stress intensity values for crack growth in Type 316NG SS, and the effects of cuprous ion and several organic salts on the SCC of sensitized Type 304 SS. Crevice conditions were observed to strongly promote SCC. Significant heat-to-heat variations were observed in SCC susceptibility of Types 316NG and 347 SS. No correlation was found between SCC behavior and minor variations in chemical composition. A significant effect of heat treatment was observed in Type 347 SS. A heat that was extremely resistant to SCC after heat treatment at 650/degree/C for 24 h was susceptible to transgranular stress corrosion cracking (TGSCC) in the solution-annealed condition. Although there was no sensitization in either condition, the presence or absence of precipitates and differences in precipitate morphology appear to influence the SCC behavior. 20 refs., 20 figs., 11 tabs.
Date: October 1, 1988
Creator: Shack, W.J.; Kassner, T.F.; Maiya, P.S.; Park, J.Y. & Ruther, W.E.
Partner: UNT Libraries Government Documents Department

BWR pipe crack and weld clad overlay studies

Description: Leaks and cracks in the heat-affected zones of weldments in austenitic stainless steel piping in boiling water reactors (BWRs) due to intergranular stress corrosion cracking (IGSCC) have been observed since the mid-1960s. Since that time, cracking has continued to occur, and indication have been found in all parts of the recirculation system, including the largest diameter lines. Proposed solutions for the problem include procedures that produce a more favorable residual stress state on the inner surface, materials that are more resistant to stress corrosion cracking (SCC), and changes in the reactor environment that decrease the susceptibility to cracking. In addition to the evaluation of these remedies, it is also important to gain a better understanding of the weld overlay procedure, which is the most widely used short-term repair for flawed piping.
Date: October 1, 1984
Creator: Shack, W.J.; Kassner, T.F.; Maiya, P.S.; Park, J.Y. & Ruther, W.E.
Partner: UNT Libraries Government Documents Department

Stress corrosion crack growth rates in Type 304 stainless steel in simulated BWR environments

Description: Stress corrosion cracking of Type 304 stainless steel has been studied with fracture-mechanics-type standard 25.4-mm-thick compact tension specimens in simulated boiling-water reactor environments at 289/sup 0/C and 8.3 MPa. Tests were performed with either constant or cyclic loading. The latter tests used a positive sawtooth waveform with an unloading time of 1 or 5 s, a load ratio R (minimum load to maximum load) of 0.2 to 0.95, and a frequency f of 8 x 10/sup -4/ to 1 x 10/sup -1/ Hz. Crack lengths and crack growth rates were determined by the compliance method; crack mouth opening displacement was measured with in-situ clip gauges. Fractography was used to examine the mode of cracking and to confirm the compliance method for crack length determination. The test environments were high-purity deionized water with 0.2- to 8-ppM dissolved oxygen, and water with 0.2-ppM dissolved oxygen and 0.1-ppM sulfate (as H/sub 2/SO/sub 4/). Two heats with a carbon content of 0.06 wt % were investigated in solution-heat-treated and furnace-sensitized conditions. Degree of sensitization varied from approx. 0 to 20 C/cm/sup 2/ as measured by the electrochemical potentiokinetic polarization method. 8 references, 7 figures, 5 tables.
Date: November 1, 1984
Creator: Park, J.Y.; Ruther, W.E.; Kassner, T.F. & Shack, W.J.
Partner: UNT Libraries Government Documents Department

BWR pipe crack remedies evaluation

Description: This paper presents results on: (a) the influence of simulated BWR environments on the stress-corrosion-craking (SCC) susceptibility of Types 304, 316NG, and 347 stainless (SS); (b) fracture-mechanics crack-growth-rate measurements on these materials and weld overlay specimens in different environments; and (c) residual stress measurements and metallographic evaluations of conventional pipe weldments treated by a mechanical-stress-improvement process (MSIP) as well as those produced by a narrow-gap welding procedure. Crack initiation studies on Types 304 and 316NG SS under crevice and non-crevice conditions in 289/sup 0/C water containing 0.25 ppM dissolved oxygen with low sulfate concentrations indicate that SCC initiates at very low strains (<3%) in the nuclear grade material. Crack growth measurements on fracture-mechanics-type specimens, under low-frequency cyclic loading, show that the Type 316NG steel cracks at a somewhat lower rate (approx.40%) than sensitized Type 304 SS in an impurity environment with 0.25 ppM dissolved-oxygen; however, the latter material stops cracking when sulfate is removed from the water. Crack growth in both materials ceases under simulated hydrogen-water chemistry conditions (<5 ppB oxygen) even with 100 ppB sulfate present in the water. An unexpected result was obtained in the test on a weld overlay specimen in the impurity environment, viz., the crack grew to the overlay interface at a nominal rate, branched at 90/sup 0/ in both directions, and then grew at high rate (parallel to the nominal applied load). Residual stress measurements on MSIP-treated weldments and those produced by a narrow-gap welding procedure indicate that these techniques produce compressive stresses over most of the inner surface near the weld and heat-affected zones.
Date: October 1, 1986
Creator: Shack, W.J.; Kassner, T.F.; Maiya, P.S.; Park, J.Y. & Ruther, W.E.
Partner: UNT Libraries Government Documents Department

Stainless steel-zirconium alloy waste forms

Description: An electrometallurgical treatment process has been developed by Argonne National Laboratory to convert various types of spent nuclear fuels into stable storage forms and waste forms for repository disposal. The first application of this process will be to treat spent fuel alloys from the Experimental Breeder Reactor-II. Three distinct product streams emanate from the electrorefining process: (1) refined uranium; (2) fission products and actinides extracted from the electrolyte salt that are processed into a mineral waste form; and (3) metallic wastes left behind at the completion of the electrorefining step. The third product stream (i.e., the metal waste stream) is the subject of this paper. The metal waste stream contains components of the chopped spent fuel that are unaffected by the electrorefining process because of their electrochemically ``noble`` nature; this includes the cladding hulls, noble metal fission products (NMFP), and, in specific cases, zirconium from metal fuel alloys. The selected method for the consolidation and stabilization of the metal waste stream is melting and casting into a uniform, corrosion-resistant alloy. The waste form casting process will be carried out in a controlled-atmosphere furnace at high temperatures with a molten salt flux. Spent fuels with both stainless steel and Zircaloy cladding are being evaluated for treatment; thus, stainless steel-rich and Zircaloy-rich waste forms are being developed. Although the primary disposition option for the actinides is the mineral waste form, the concept of incorporating the TRU-bearing product into the metal waste form has enough potential to warrant investigation.
Date: July 1996
Creator: McDeavitt, S. M.; Abraham, D. P.; Keiser, D. D., Jr. & Park, J. Y.
Partner: UNT Libraries Government Documents Department

Alloy waste forms for metal fission products and actinides isolated by spent nuclear fuel treatment

Description: Waste form alloys are being developed at Argonne National Laboratory for the disposal of remnant metallic wastes from an electrometallurgical process developed to treat spent nuclear fuel. This metal waste form consists of the fuel cladding (stainless steel or Zircaloy), noble metal fission products (e.g., Ru, Pd, Mo and Tc), and other metallic wastes. The main constituents of the metal waste stream are the cladding hulls (85 to 90 wt%); using the hulls as the dominant alloying component minimizes the overall waste volume as compared to vitrification or metal encapsulation. Two nominal compositions for the waste form are being developed: (1) stainless steel-15 wt% zirconium for stainless steel-clad fuels and (2) zirconium-8 wt% stainless steel for Zircaloy-clad fuels. The noble metal fission products are the primary source of radiation in the metal waste form. However, inclusion of actinides in the metal waste form is being investigated as an option for interim or ultimate storage. Simulated waste form alloys were prepared and analyzed to determine the baseline alloy microstructures and the microstructural distribution of noble metals and actinides. Corrosion tests of the metal waste form alloys indicate that they are highly resistant to corrosion.
Date: October 1, 1996
Creator: McDeavitt, S.M.; Abraham, D.P.; Keiser, D.D. Jr. & Park, J.Y.
Partner: UNT Libraries Government Documents Department

Stainless steel-zirconium alloy waste forms for metallic fission products and actinides during treatment of spent nuclear fuel

Description: Stainless steel-zirconium waste form alloys are being developed for the disposal of metallic wastes recovered from spent nuclear fuel using an electrometallurgical process developed by Argonne National Laboratory. The metal waste form comprises the fuel cladding, noble metal fission products and other metallic constituents. Two nominal waste form compositions are being developed: (1) stainless steel-15 wt% zirconium for stainless steel-clad fuels. The noble metal fission products are the primary source of radiation and their contribution to the waste form radioactivity has been calculated. The disposition of actinide metals in the waste alloys is also being explored. Simulated waste form alloys were prepared to study the baseline alloy microstructures and the microstructural distribution of noble metals and actinides, and to evaluate corrosion performance.
Date: July 1, 1996
Creator: McDeavitt, S.M.; Abraham, D.P.; Park, J.-Y. & Keiser, D.D. Jr.
Partner: UNT Libraries Government Documents Department

Crack-growth-rate testing of candidate waste container materials

Description: Fracture-mechanics crack growth tests were conducted on 25.4-mm-thick compact tension specimens of Types 304L and 316L stainless steel (SS) and Incoloy 825 at 93{degree}C and 1 atmosphere of pressure is simulated J-13 well water, which is representative of the groundwater at the Yucca Mountain site in Nevada that is proposed for a high-level nuclear waste repository. Crack growth rates were measured under various load conditions: load ratios (R) of 0.5--1.0, frequencies of 10{sup {minus}3}{minus}1 Hz, rise times of 1--1000 s, and peak stress intensities of 25--40 MPa{center_dot}m{sup 1/2}. The measured crack growth rates are bounded by the predicted rates from the current ASME Section XI correlation for fatigue crack growth rates of austenitic stainless steel in air. Environmentally accelerated crack growth was not evident in any of the three materials under the test conditions investigated.
Date: December 31, 1991
Creator: Park, J.Y.; Shack, W.J. & Diercks, D.R.
Partner: UNT Libraries Government Documents Department

Eddy current analysis round robin using the NRC steam generator mockup.

Description: This paper discusses round-robin exercises to assess inspection reliability using the NRC steam generator (SG) mock-up at Argonne National Laboratory. The purpose of the round robins is to assess the current reliability of SG tubing inservice inspection, determine the probability of detection (POD) as function of flaw size or severity, and assess the capability for sizing of flaws. The mock-up contains hundreds of cracks and simulations of artifacts such as corrosion deposits and tube support plates that make detection and characterization of cracks more difficult in operating steam generators than in most laboratory situations. Eddy current signals from the laboratory-grown cracks used in the mock-up have been reviewed to ensure that they provide reasonable simulations of those obtained in the field. The mock-up contains 400 tube openings. Each tube contains nine 22.2-mm (7/8-in.) diameter, 30.5-cm (1-ft) long, Alloy 600 test sections. The flaws are located in the tube sheet near the roll transition zone (RTZ), in the tube support plate (TSP), and in the freespan. The flaws are primarily intergranular stress corrosion cracks (axial and circumferential, ID and OD). In addition to the simulated tube sheet and TSP the mock-up has simulated sludge and magnetite deposits. A validated multiparameter eddy current algorithm that provided a detailed isometric plot for every flaw was used to establish the reference state of defects in the mock-up. The detection results for the 11 teams were used to develop POD curves as a function of maximum depth, voltage and the parameter m{sub p}, for the various types of flaws. The 95% one-sided confidence limits (OSL), which include errors in maximum depth estimates, are presented along with the POD curves. For the second round robin a reconfigured mock-up is being used to evaluate the effectiveness of eddy current arrays.
Date: February 20, 2002
Creator: Kupperman, D. S.; Muscara, J.; Bakhtiari, S.; Park, J. Y. & Shack, W. J.
Partner: UNT Libraries Government Documents Department

Proceedings of the USNRC/EPRI/ANL heated crevice seminar.

Description: An international Heated Crevice Seminar, sponsored by the Division of Engineering Technology, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, Argonne National Laboratory, and the Electric Power Research Institute, was held at Argonne National Laboratory on October 7-11, 2002. The objective of the seminar was to provide a working forum for the exchange of information by contributing experts on current issues related to corrosion in heated crevices, particularly as it relates to the integrity of PWR steam generator tubes. Forty-five persons from six countries attended the seminar, including representatives from government agencies, private industry and consultants, government research laboratories, nuclear vendors, and electrical utilities. The seminar opened with keynote talks on secondary-side crevice environments associated with IGA and IGSCC of mill-annealed Alloy 600 steam generator tubes and the submodes of corrosion in heat transfer crevices. This was followed by technical sessions on (1) Corrosion in Crevice Geometries, (2) Experimental Methods, (3) Results from Experimental Studies, and (4) Modeling. The seminar concluded with a panel discussion on the present understanding of corrosive processes in heated crevices and future research needs.
Date: August 31, 2003
Creator: Park, J. Y.; Fruzzetti, K.; Muscara, J.; Diercks, D. R.; Technology, Energy; EPRI et al.
Partner: UNT Libraries Government Documents Department

Environmentally assisted cracking in light water reactors

Description: Topics that have been investigated during this year include (1) SCC of A533-Gr B steel used in steam generator and reactor pressure vessels, (2) fatigue of Type 316NG SS, and (3) SCC of Type 347 and CF-3 cast duplex stainless steels in simulated BWR water. Crack-growth-rate (CGR) tests were performed on a composite A533-Gr B/Inconel-182 specimen in which the stress corrosion crack in the Inconel-182 weld metal penetrated and grew into the A533-Gr B steel. CGR tests were also conducted on conventional (unplated) and nickel- or gold-plated A533-Gr B specimens to provide insight into whether the nature of the surface layer on the low-alloy steel, either oxide corrosion products or a noble metal, influences the overall SCC process. CGR data on the A533-Gr B specimens were compared with the fatigue crack reference curves in the ASME Boiler and Pressure Vessel Code, Section XI, Appendix A. Fatigue tests were conducted on Type 316NG SS in air and simulated BWR water at low strain ranges and frequencies to better establish margins in the ASME Code Section III Fatigue Design Curves. CGR tests were also conducted on specimens of Type 347 SS with different heat-treatment conditions, and a specimen of CF-3 cast stainless steel with a ferrite content of 15.6%. The results were compared with previous data on another heat of Type 347 SS, which was very resistant to SCC, and a CF-3M steel with a ferrite content of 5%. 37 refs., 15 figs., 8 tabs.
Date: December 1, 1990
Creator: Park, J.Y.; Ruther, W.E.; Kassner, T.F. & Shack, W.J.
Partner: UNT Libraries Government Documents Department

Evaluation of stainless steel pipe cracking: causes and fixes

Description: Leaks and cracks in the heat-affected zones of weldments in austenitic stainless steel piping and associated components of boiling water reactors (BWRs) have been observed since the mid-1960s. Since that time, cracking has continued to occur and indications have been found in all parts of the recirculation system, including the largest diameter lines. Proposed solutions include remedies primarily intended to produce a more favorable residual stress state, materials which are more resistant to stress corrosion cracking (SCC), and changes in the reactor environment which decrease the susceptibility to cracking. In addition to evaluating these remedies, it is also important to gain a better understanding of key variables such as residual stresses, crack growth rates, and the leak-before-break margin in flawed piping, which may impact regulatory decisions on operating plants. The main areas of effort during the past year have been (1) studies of impurity effects on susceptibility to intergranular stress corrosion cracking (IGSCC), (2) crack growth rate measurements, (3) finite-element studies of residual stress produced by induction heating stress improvement (IHSI) and the addition of weld overlays to flawed piping, (4) leak-before-break analyses of piping with 360/sup 0/ part-through cracks, and (5) parametric studies on the effect of through-wall residual stresses on IGSCC crack growth behavior in large-diameter piping weldments. 5 references, 15 figures, 2 tables.
Date: October 1, 1983
Creator: Shack, W.J..; Kassner, T.F.; Maiya, P.S.; Nichols, F.A.; Park, J.Y.; Ruther, W. et al.
Partner: UNT Libraries Government Documents Department

BWR pipe crack and weld clad overlay studies

Description: This paper presents results on (a) the influence of simulated BWR environments and temperature on the intergranular-stress-corrosion cracking (IGSCC) susceptibility of sensitized stainless steels (SS), (b) the stress-corrosion susceptibility of alternative piping materials, (c) analysis of field components to assess the effectiveness of in-service inspection techniques and the in-reactor performance of weld overlay repairs, and (d) finite-element analyses and experimental measurement of residual stresses in weldments with weld overlays. Fracture-mechanics crack-growth data are presented to confirm correlations between the critical corrosion potentials required to inhibit IGSCC and the level of impurities in the environment. Slow-strain-rate tests show that very low levels of impurities (25 ppb of sulfate) can produce suseptibility to transgranular-stress-corrosion cracking (TGSCC) in Type 316NG SS and that nitrogen levels is SS above 0.1 wt. % appear to increase susceptibility to TGSCC. Preliminary results on a German Type 347NG SS suggest that it is at least as resistant to TGSCC in impurity environments as Type 316NG SS. Measurements on overlay weldments removed from the Hatch-2 reactor confirm that compressive residual stresses are produced on the inner surface of the weldments by the overlay.
Date: October 1, 1985
Creator: Shack, W.J.; Kassner, T.F.; Maiya, P.S.; Park, J.Y.; Ruther, W.E. & Rybicki, E.F.
Partner: UNT Libraries Government Documents Department