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FEA stress analysis for SAFKEG 2863B

Description: This report covers the evaluation of the structural design of the two stainless steel containment vessels in CROFT SAFKEG Model Number 2863B, for conformance to the design criteria of the NRC Regulatory Guide 7.6, NRC Regulatory Guide 7.8, and the applicable requirements of the ASME Boiler and Pressure Vessel Code, Section 3, and Section 8. The two containment vessels are designated Cans 2870 and 2871. Each of these containment vessels was analyzed for the loadings specified in chapter 2, Section 2.1.2 of the SARP. Structural assessment of Cans 2870 and 2871 due to loading considerations beyond the evaluation of pressure and temperature are presented. This report is organized as follows: (1) overview of the design of each containment vessel and pressure boundary; (2) brief description of both containment vessels; (3) discussion of normal and accident conditions; (4) analysis assumptions; (5) detailed structural evaluation of each component of each containment vessel; (6) demonstration of compliance to Regulatory Guide 7.6 stress evaluations; (7) demonstration of compliance to Regulatory Guide 7.8 loading combinations; and (8) summary of the calculated stresses, comparison with design allowables, estimates of margins of safety and a summary of results and conclusions.
Date: July 15, 1997
Creator: Puckett, A.
Partner: UNT Libraries Government Documents Department

Tensile stress corrosion cracking of type 304 stainless steel irradiated to very high dose

Description: Certain safety-related core internal structural components of light water reactors, usually fabricated from Type 304 or 316 austenitic stainless steels (SSs), accumulate very high levels of irradiation damage (20--100 displacement per atom or dpa) by the end of life. The data bases and mechanistic understanding of, the degradation of such highly irradiated components, however, are not well established. A key question is the nature of irradiation-assisted intergranular cracking at very high dose, i.e., is it purely mechanical failure or is it stress-commotion cracking? In this work, hot-cell tests and microstructural characterization were performed on Type 304 SS from the hexagonal fuel can of the decommissioned EBR-11 reactor after irradiation to {approximately}50 dpa at {approximately}370 C. Slow-strain-rate tensile tests were conducted at 289 C in air and in water at several levels of electrochemical potential (ECP), and microstructural characteristics were analyzed by scanning and transmission electron microcopies. The material deformed significantly by twinning and exhibited surprisingly high ductility in air, but was susceptible to severe intergranular stress corrosion cracking (IGSCC) at high ECP. Low levels of dissolved O and ECP were effective in suppressing the susceptibility of the heavily irradiated material to IGSCC, indicating that the stress corrosion process associated with irradiation-induced grain-boundary Cr depletion, rather than purely mechanical separation of grain boundaries, plays the dominant role. However, although IGSCC was suppressed, the material was susceptible to dislocation channeling at low ECP, and this susceptibility led to poor work-hardening capability and low ductility.
Date: September 1, 2001
Creator: Chung, H. M.; Ruther, W. E.; Strain, R. V. & Shack, W. J.
Partner: UNT Libraries Government Documents Department

Localized weld metal corrosion in stainless steel water tanks

Description: The rapidly developed leaks within the TFC and TFD tanks (LLNL groundwater treatment facilities) were caused by localized corrosion within the resolidified weld metal. The corrosion was initiated by the severe oxidation of the backsides of the welds which left the exposed surfaces in a condition highly susceptible to aqueous corrosion. The propagation of surface corrosion through the thickness of the welds occurred by localized corrosive attack. This localized attack was promoted by the presence of shielded aqueous environments provided by crevices at the root of the partial penetration welds. In addition to rapid corrosion of oxidized surfaces, calcium carbonate precipitation provided an additional source of physical shielding from the bulk tank environment. Qualification testing of alternate weld procedures showed that corrosion damage can be prevented in 304L stainless steel GTA welds by welding from both sides while preventing oxidation of the tank interior through the use of an inert backing gas such as argon. Corrosion resistance was also satisfactory in GMA welds in which oxidized surfaces were postweld cleaned by wire brushing and chemically passivated in nitric acid. Further improvements in corrosion resistance are expected from a Mo-containing grade of stainless steel such as type 316L, although test results were similar for type 304L sheet welded with type 308L filler metal and type 316L sheet welded with type 316L filler metal.
Date: May 25, 1995
Creator: Strum, M.J.
Partner: UNT Libraries Government Documents Department

Phase transformations in engineering materials

Description: Phase transformations in engineering materials are inevitably related to mechanical behavior and are often precursors to residual stress and distortion. Neutron scattering in general is a valuable tool for studying their effects, and pulsed neutrons are of special value, because of the inherently comprehensive crystallographic coverage they provide in each measurement. At the Manuel Lujan neutron scattering center several different research programs have addressed the relationships between phase transformation/mechanical behavior and residual strains. Three disparate examples are presented; (1) stress induced transformation in a NiTi shape memory alloy, (2) cryogenically induced transformation in a quenched 5180 steel, and (3) time resolved evolution of strain induced martensite in 304 stainless steel. In each case a brief description of the principle result will be discussed in the context of using neutrons for the measurement.
Date: June 1, 1996
Creator: Bourke, M.A.M.; Lawson, A.C.; Dunand, D.C. & Priesmeyer, H.G.
Partner: UNT Libraries Government Documents Department

Packaging radioactive wastes for geologic disposal

Description: The M&O contractor for the DOE Office of Civilian Radioactive Waste Management is developing designs of waste packages that will contain the spent nuclear fuel assemblies from commercial and Navy reactor plants and various civilian and government research reactor plants, as well as high-level wastes vitrified in glass. The safe and cost effective disposal of the large and growing stockpile of nuclear waste is of national concern and has generated political and technical debate. This paper addresses the technical aspects of disposing of these wastes in large and robust waste packages. The paper discusses the evolution of waste package design and describes the current concepts. In addition, the engineering and regulatory issues that have governed the development are summarized and the expected performance in meeting the requirements are discussed.
Date: August 1, 1996
Creator: Benton, H.A.
Partner: UNT Libraries Government Documents Department

Upset welded 304L and 316L vessels for storage tests

Description: Two sets of vessels for tritium storage tests were fabricated using upset welding. A solid-state resistance upset weld was used to join the two halves of each vessel at the girth. The vessels differ from production reservoirs in design, material, and fabrication process. One set was made from forged 304L stainless steel and the other from forged 316L stainless steel. Six vessels of each type were loaded with a tritium mix in November 1995 and placed in storage at 71 C. This memo describes and documents the fabrication of the twelve vessels.
Date: April 1996
Creator: Kanne, W. R., Jr.
Partner: UNT Libraries Government Documents Department

Phase stability in austenitic stainless steels -- New approaches, results, and their relation to properties

Description: In recent years, the phase stability of austenitic stainless steels, and its effect on the mechanical properties of stainless steels, have been the subject of much interest. With the availability of new experimental techniques, new theoretical methods, and new computational procedures, significant advances have been made in understanding, and being able to predict, phase stability and mechanical properties of stainless steel welds. This paper reviews some of these developments, with an emphasis on recent work that has been done at Oak Ridge National Laboratory.
Date: December 31, 1995
Creator: Vitek, J.M. & David, S.A.
Partner: UNT Libraries Government Documents Department

Deposition of biaxially textured yttria-stabilized zirconia by ion-beam-assisted deposition.

Description: Biaxially textured yttria (8 mol %)-stabilized zirconia (YSZ) thin films were deposited on randomly oriented Hastelloy C and Stainless Steel 304 at room temperature as a buffer layer for subsequent deposition of oriented YBa{sub 2}Cu{sub 3}O{sub x} films. The 0.16-1.3 {micro}m thick YSZ films were deposited by e-beam evaporation at rates of 1.2-3.2 {angstrom}/sec. Biaxially textured films were produced with an Ar/O{sub 2} ion beam directed at the substrate during film growth. X-ray diffraction was used to study in-plane and out-of-plane orientation as a function of ion-bombardment angle, film thickness, ion-to-atom flux ratio, and substrate material. In-plane and out-of-plane average-misorientation angles on these YSZ films that were deposited by ion-beam-assisted deposition were as low as 17 and 5.4{degree}, respectively, on as-received substrates.
Date: September 17, 1998
Creator: Chudzik, M. P.
Partner: UNT Libraries Government Documents Department

Estimates of margins in ASME Code strength values for stainless steel nuclear piping

Description: The margins in the ASME Code stainless steel allowable stress values that can be attributed to the variations in material strength are evaluated for nuclear piping steels. Best-fit curves were calculated for the material test data that were used to determine allowable stress values for stainless steels in the ASME Code, supplemented by more recent data, to estimate the mean stresses. The mean yield stresses (on which the stainless steel S{sub m} values are based) from the test data are about 15 to 20% greater than the ASME Code yield stress values. The ASME Code yield stress values are estimated to approximately coincide with the 97% confidence limit from the test data. The mean and 97% confidence limit values can be used in the probabilistic risk assessments of nuclear piping.
Date: November 1, 1995
Creator: Ware, A.G.
Partner: UNT Libraries Government Documents Department

The effect of low dose-rate irradiation on the microstructure of 304 stainless steel.

Description: Changes in mechanical and corrosion properties caused by the development of radiation-induced microstructure have relevance to the aging and lifetime extension of light water reactors (LWR's). However, much of the current data related to microstructural development in irradiated metals are generated from studies carried out at much higher dose-rates than encountered in LWR's. An opportunity exists to study the influence of low dose-rate irradiation on microstructural development for a variety of structural and surveillance materials extracted from the experimental breeder reactor EBR-II. In this study, irradiated 304 stainless steel hexagonal ''hex'' duct material is examined in order to compare microstructure in the dose-rate range of 10{sup {minus}7}-10{sup {minus}9} dpakec. The samples, taken from the reflector locations in EBR-II, experienced a total dose between 10 and 12 dpa at a temperature of {approximately}375 C. Transmission electron microscopy (TEM) results reveal that there is a moderate dose-rate effect on microstructural development for samples irradiated in the range of 2 x 10{sup {minus}8} to 4 x 10{sup {minus}8} dpa/sec, however a substantial dose rate-effect exists between dose-rates of 2 x 10{sup {minus}8} and 1 x 10{sup {minus}9} dpa/sec Transmission electron microscopy (TEM) results will detail the development of the microstructure in terms of radiation-induced cavities, dislocations, and precipitates.
Date: December 2, 1998
Creator: Cole, J. I.
Partner: UNT Libraries Government Documents Department

Modeling and validation of multiple joint reflections for ultra- narrow gap laser welding

Description: The effects of multiple internal reflections within a laser weld joint as a function of joint geometry and processing conditions have been characterized. A computer model utilizing optical ray tracing is used to predict the reflective propagation of laser beam energy focused into the narrow gap of a metal joint for the purpose of predicting the location of melting and coalescence which form the weld. The model allows quantitative analysis of the effects of changes to joint geometry, laser design, materials and processing variables. This analysis method is proposed as a way to enhance process efficiency and design laser welds which display deep penetration and high depth to width aspect ratios, reduced occurrence of defects and enhanced melting. Of particular interest to laser welding is the enhancement of energy coupling to highly reflective materials. The weld joint is designed to act as an optical element which propagates and concentrates the laser energy deep within the joint to be welded. Experimentation has shown that it is possible to produce welds using multiple passes to achieve deep penetration and high depth to width aspect ratios without the use of filler material. The enhanced laser melting and welding of aluminum has been demonstrated. Optimization through modeling and experimental validation has resulted in the development of a laser welding process variant we refer to as Ultra-Narrow Gap Laser Welding.
Date: December 1, 1995
Creator: Milewski, J.; Keel, G. & Sklar, E.
Partner: UNT Libraries Government Documents Department

Prevention for possible microbiologically influenced corrosion (MIC) in RHLWE flush water system

Description: This report is in response to the request to provide a recommendation for the prevention of possible microbiologically influenced corrosion (MIC) for the RHLWE (Replacement High-Level Waste Evaporator) flush water (FW) system. The recent occurrences of MIC at DWPF prompted HLWE to evaluate the possibility of MIC occurring in this 304L stainless steel RHLWE flush water system. Concern was heightened by the fact that the well water used and the other conditions at H-Tank Farm are similar to those at DWPF. However, only one known leak has occurred in the existing 304L evaporator flush water systems in either tank farm (in 1H system), and no MIC Corrosion has been confirmed in the tank farm area. The design of the RHLWE flush water system (completed long before the occurrence of MIC at DWPF) was modeled after the existing evaporator flush water systems and did not specifically include MIC prevention considerations. Therefore, MIC prevention was not specifically considered during the design phase of this flush water system. The system is presently being installed. After an extensive evaluation, a task team concluded that the best biocide to prevent the occurrence of MIC would be NaOH at fairly low concentration. Sodium hydroxide (NaOH) is optimal in this application, because of its effectiveness, low cost, and familiarity to the Operations personnel (see Appendix A). However, it is the opinion of the task group that application should be withheld until MIC corrosion is demonstrated in the system.
Date: July 10, 1995
Creator: Hsu, T.C. & Jenkins, C.F.
Partner: UNT Libraries Government Documents Department

Ultrahigh-current-density metal-ion implantation and diamondlike-hydrocarbon films for tribological applications; Final report

Description: The metal-ion-implantation system used to implant metals into substrates are described. The metal vapor required for operation is supplied by drawing sufficient electron current from the plasma discharge to an anode-potential crucible so a solid, pure metal placed in the crucible will be heated to the point of vaporization. The ion-producing, plasma discharge is initiated within a graphite-ion-source body, which operates at high temperature, by using an argon flow that is turned off once the metal vapor is present. Extraction of ion beams several cm in diameter at current densities ranging to several hundred {mu}A/cm{sup 2} on a target 50 cm downstream of the ion source have been demonstrated using Mg, Ag, Cr, Cu, Si, Ti, V, B and Zr. These metals were implanted into over 100 substrates (discs, pins, flats, wires). A model describing thermal stresses induced in materials (e.g. ceramic plates) during high-current-density implantation is presented. Tribological and microstructural characteristics of iron and 304-stainless-steel samples implanted with Ti or B are examined. Diamondlike-hydrocarbon coatings were applied to steel surfaces and found to exhibit good tribological performance.
Date: September 1993
Creator: Wilbur, P. J.
Partner: UNT Libraries Government Documents Department

A Scanning Auger Microprobe analysis of corrosion products associated with sulfate reducing bacteria

Description: A Scanning Auger Microprobe analysis was performed on the corrosion products of an austenitic AISI type 304 SS after a potentiostatic polarization of one volt for ten minutes in a modified Postgate`s C media containing sulfate reducing bacteria. The corrosion products were characterized and mapped in local regions where pitting was observed. A critical evaluation of the applicability of this technique for the examination of microbially influenced corrosion (MIC) is presented.
Date: March 1, 1995
Creator: Sadowski, R.A.; Chen, G.; Clayton, C.R.; Kearns, J.R.; Gillow, J.B. & Francis, A.J.
Partner: UNT Libraries Government Documents Department


Description: The potential-current density relationships for 304 stainless steel dissolution in a nitrate system were studied as a function of solution composition and temperature in order to optimize the conditions for electrolytic dissolution of ihis material. In the nitrate system, the anodic dissolution of steel takes place in the transpassive region. Under some conditions, deviations from Tafel behavior are observed which depend greatly on the nitrate and hydrogen ion concentration, and on temperature. A discussion of passivity, transpassivity, secondary passivation, the limiting current density, and the effect of alloy composition on the dissolution behavior is given. It was found that at temperatures above 60 deg C efficient dissolver operation should be possible over a wide range of solution compositions and at current densities up to 2 amp/cm/sup 2/. (auth)
Date: June 1, 1962
Creator: Aylward, J. R. & Whitener, E. M.
Partner: UNT Libraries Government Documents Department

Inelastic deformation and damage at high temperature. Progress report, April 1, 1991--March 31, 1992

Description: Combined experimental and theoretical investigations into the inelastic deformation and damage behavior of engineering alloys at elevated temperatures are being pursued. The analysis of previously performed strain rate change and relaxation tests on modified 9Cr-1Mo steel showed the need for inclusion of a recovery of state term in the growth laws for the state variables of the viscoplasticity theory based on overstress (VBO). Recovery of state terms were introduced and the experimental results were satisfactorily simulated. The finite deformation theory of VBO has been developed further to include a convected derivative rationale for the choice of the objective stress rate. The reversing direct current voltage drop measurements during low cycle fatigue at elevated temperature were improved. A passive filter bank and new positioning devices for the coils were installed. Tests at 650{degrees}C and lasting several days showed excessive, uncontrollable temperature changes. It was decided to drop the test temperature to 538{degrees}C which is close to the operating temperature of Type 304 Stainless Steel. The temperature fluctuations in torsion tests were within {plus_minus}3{degrees}C which was considered satisfactory. Testing will continue at 538{degrees}C.
Date: May 1, 1992
Creator: Krempl, E.
Partner: UNT Libraries Government Documents Department

Defect-solute interactions near irradiation grain boundaries

Description: Defect-solute interactions control radiation-induced segregation (RIS) to interfacial sinks, such as grain boundaries, in metallic materials. The best studied system in this regard has been austenitic stainless steels. Measurements of grain boundary composition indicate that RIS of major alloying elements are in reasonable agreement with inverse-Kirkendall predictions. The steep and narrow composition profiles are shown to result from limited back diffusion near the boundary. Subsequently, defect-solute interactions that affect the near boundary defect concentrations strongly affect RIS. The variability in measured RIS may in part be caused by grain boundary characteristics.
Date: November 1, 1993
Creator: Simonen, E. P.; Vetrano, J. S.; Heinisch, H. L. & Bruemmer, S. M.
Partner: UNT Libraries Government Documents Department

AEM and AES of radiation-induced segregation in proton-irradiated stainless steels

Description: In order to avoid complications from long-term induced radioactivity of neutron-irradiated specimens, 4 type 304L alloys were irradiated to 1 dpa with 3.4 MeV protons at 400 C. Analytical electron microscopy and Auger electron spectrometry were used to measure composition at and near grain boundaries in controlled purity alloys. As a result of the narrow RIS profiles (<20 nm width) at grain boundaries induced in these materials by low temperature irradiation and the finite size of the excited volume for x-ray microanalysis, the measured profiles are convolutions of these two factors.
Date: June 1, 1994
Creator: Kenik, E. A.; Carter, R. D.; Damcott, D. L.; Atzmon, M. & Was, G. S.
Partner: UNT Libraries Government Documents Department

Effect of vibratory stress relief during welding of thick stainless steel plate

Description: Residual strains were measured in two welded 25-mm thick plates of type 304 stainless steel by the neutron diffraction technique. The filler metal employed to weld these plates was type 308 stainless steel. One of the two welds was prepared without any vibratory stress relief treatment and the other was vibrated at a frequency below the resonant condition which gives a fraction the resonant amplitude during welding. In both plates the largest residual stress component found in the heat affected zone and in the base metal is along the fusion joint (longitudinal) and is found at the boundary between the weld zone and the heat affected zone. This longitudinal component is 300{plus_minus}50 MPa in tension. The associated normal stress was close to zero and the transverse stress was 80{plus_minus}50 MPa. Variations in residual stresses with thickness through the base metal plate were small. The treated plate and untreated plate showed nearly identical patterns of stress distribution. Differences in the measured stresses between the vibratory-stress-relief treated and the untreated plates fall within the error bars of the stress determination in these particular 25 mm thick 300-type stainless steel plates.
Date: December 31, 1993
Creator: Spooner, S.; David, S. A.; Wang, X. L.; Hubbard, C. R.; Holden, T. M. & Root, J. H.
Partner: UNT Libraries Government Documents Department

The effects of tritium and decay helium on the fracture toughness properties of stainless steels

Description: J-integral fracture mechanics techniques and scanning electron microscopy observations were used to investigate the effects of tritium and its decay product, helium-3, on Types 304L, 316L, 21-6-9, A286, and JBK-75 (Modified A286) stainless steels. Tritium-exposed samples of each steel had lower fracture toughness values and less resistance to stable crack growth than control samples. Type 316L stainless steel was more resistant to the embrittling effects of tritium and decay helium than the other steels.
Date: December 31, 1991
Creator: Morgan, M. J.
Partner: UNT Libraries Government Documents Department

Thermomechanical history measurements on Type 304L stainless steel pipe girth welds

Description: Thermal and strain histories were recorded for three 40-cm-diameter (16 inch), Type 304L stainless steel (SS), schedule 40 (1.27 cm thickness) pipe girth welds. Two weld groove preparations were standard V grooves while the third was a narrow groove configuration. The welding parameters for the three pipe welds simulated expected field practice as closely as possible. The narrow gap weld was completed in four continuous passes while the other two welds required six and nine (discontinuous) passes, due to the use of different weld wire diameters. Thermomechanical history measurements were taken on the inner counterbore surface, encompassing the weld centerline and heat-affected zone (HAZ), as well as 10 cm of inner counterbore surface on either side of the weld centerline; a total of 47 data acquisition instruments were used for each weld. These instruments monitored: (1) weld shrinkages parallel to the pipe axis; (2) surface temperatures; (3) surface strains parallel to weld centerline; and (4) radial deformations. Results show that the weld and HAZ experienced cyclic deformation in the radial direction during welding, indicating that the final residual stress distribution in multi-pass pipe weldments is not axisymmetric. Measured radial and axial deformations were smaller for the narrow gap groove than for the standard V grooves, suggesting that the narrow gap groove weldment may have lower residual stress levels than the standard V groove weldments. This study provides the experimental database and a guideline for further computational modeling work.
Date: December 31, 1993
Creator: Li, Ming; Atteridge, D. G.; Anderson, W. E.; Turpin, R. & West, S. L.
Partner: UNT Libraries Government Documents Department

Fill tube bore inspection with machine vision

Description: A semi-automated technique for bore inspection of small diameter tubes is presented. The inspections are performed to insure that the bore surfaces are free of contaminants or defects. The image collectionscheme uses a borescope which is stepped along the length of the tube. An image is acquired at each step and portions from each image are combined to yield a planar image. Color analysis classifies the oxidation levels in the bore of the fill tubes. The analysis is performed by taking the image`s mean values of the red, green, and blue intensities and computing a figure of merit which is then used to estimate the relative amount of oxidation. This estimation scheme was shown to have a high level of correlation with the tube oxidation levels and the quality of the subsequent welds as determined by metallographic evaluation.Surface imperfections are detected by a series of digital filtering steps followed by a statistical analysis of the resulting binary image. The frequency parameter of the Poisson distribution for the total image and image segments are computed. A statistical significance test is performed by comparing the frequency parameter of each segment to the global statistics of the image. Fine longitudinal scratches were detected with this method.
Date: December 31, 1992
Creator: Pechersky, M. J.; Mosley, W. C. & Dickerson, R. K.
Partner: UNT Libraries Government Documents Department

Drilling with fiber-transmitted, visible lasers

Description: High power and radiance copper-vapor laser technology developed at Lawrence Livermore National Laboratory shows great promise for many materials processing tasks. The authors recently transmitted the visible light produced by these lasers through fiber optics to perform hole drilling experiments. They found the tolerances on the hole circulatory and cylindricity to be excellent when compared to that produced by conventional optics. This technique lends itself to many applications that are difficult to perform when using conventional optics, including robotic manipulation and hole drilling in non-symmetric parts.
Date: February 17, 1994
Creator: Kautz, D. D.; Berzins, L. V.; Dragon, E. P.; Werve, M. E. & Warner, B. E.
Partner: UNT Libraries Government Documents Department