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Acoustic emission from thermal-gradient cracks in UO$sub 2$

Description: A feasibility study has been conducted to evaluate the potential use of acoustic emission to monitor thermal-shock damage in direct electrical heating of UO$sub 2$ pellets. In the apparatus used for the present tests, two acoustic- emission sensors were placed on extensions of the upper and lower electrical feedthroughs. Commercially available equipment was used to accumulate acoustic- emission data. The accumulation of events displayed on a cathode-ray-tube screen indicates the total number of acoustic-emission events at a particular location within the pellet stack. These tests have indicated that acoustic emission can be used to monitor thermal-shock damage in UO$sub 2$ pellets subjected to direct- electrical heating. 8 references. (auth)
Date: January 1, 1975
Creator: Kennedy, C.R.; Kupperman, D.S. & Wrona, B.J.
Partner: UNT Libraries Government Documents Department

Microstructural Effects and Signal-Enhancement Techniques in Ultrasonic Examination of Stainless Steel

Description: Ultrasonic inspection of large-grain stainless steel and stainless steel welds is difficult, and the results obtained are not easily interpreted. In the present study, the effects of stainless steel microstructure on ultrasonic test results are described, and several signal-processing techniques for enhancing ultrasonic flaw signals are discussed.
Date: September 1976
Creator: Kupperman, D. S. & Reimann, K. J.
Partner: UNT Libraries Government Documents Department

Cracking and Healing Behavior of UO2 as Related to Pellet-Cladding Mechanical Interaction : Interim Report, July 1976

Description: A direct-electrical-heating apparatus has been designed and fabricated to investigate those nuclear-fuel-related phenomena involved in the gap closure-bridging annulus formation mechanism that can be reproduced in an out-of-reactor environment. Prototypic light-water-reactor uranium dioxide fuel-pellet temperature profiles have been generated utilizing high flow rates (approximately 700 liters/min) of helium coolant gas, and a re-circulating system has been fabricated to permit tests of up to 1000 h. Simulated light-water-reactor single- and multiple-thermal-cycle experiments will be conducted on both unclad and ceramic (fused silica) clad uranium dioxide pellet stacks. A laser dilatometer is used to measure pellet dimensional increase continuously during thermal cycling. Acoustic emissions from thermal-gradient cracking have been detected and correlated with crack length and crack area. The acoustic emissions are monitored continuously to provide instantaneous information about thermal-gradient cracking. Post-test metallography and fracture-mechanics measurements are utilized to characterize cracking and crack healing.
Date: October 1976
Creator: Kennedy, C. R.; Yaggee, F. L.; Voglewede, J. C.; Kupperman, D. S.; Wrona, B. J.; Ellingson, W. A. et al.
Partner: UNT Libraries Government Documents Department

Nondestructive-Evaluation Needs for Coal Liquefaction

Description: Nondestructive-evaluation (NDE) needs for coal liquefaction have been identified by acquiring information from site visits, a literature review, and discussions with government personnel. Nondestructive evaluation has been highly rated in importance as a way to help alleviate problems in coal-conversion systems. The primary problems are associated with highly erosive and corrosive slurries being transferred throughout the coal-conversion process. Applicable NDE techniques for both pre-service and in-service inspection include high-temperature ultrasonics, acoustic emission, radiography, acoustic holography, and ultrasonic spectroscopy.
Date: 1977?
Creator: Kupperman, D. S.
Partner: UNT Libraries Government Documents Department

Preliminary Evaluation of Several Nondestructive-Evaluation Techniques for Silicon Nitride Gas-Turbine Rotors

Description: Several nondestructive-evaluation (NDE) techniques have been examined to establish their effectiveness for detecting critically sized flaws in silicon nitride gas-turbine rotors. Preliminary results have been obtained for holographic interferometry, acoustic microscopy, dye-enhanced radiography, acoustic emission, and acoustic-impact testing techniques. This report discusses the relative effectiveness of these techniques in terms of their applicability to the rotor geometry and ability to detect critically sized flaws. Where feasible, flaw indications were verified by alternative NDE techniques or destructive examination. This study has indicated that, since the various techniques have different advantages, ultimately a reliable interrogation of ceramic rotors may require the application of several NDE methods.
Date: 1978?
Creator: Kupperman, D. S.; Sciammarella, C.; Lapinski, N. P.; Sather, A.; Yuhas, D.; Kessler, L. et al.
Partner: UNT Libraries Government Documents Department

Ultrasonic Wave-Propagation Characteristics and Polarization in Stainless Steel Weld Metal

Description: Ultrasonic inspections of austenitic stainless steel weld metal are particularly difficult because of the dendritic structure and anisotropy of the material. The acoustic properties of stainless steel weld metal are discussed. Data on frequency spectra and variations in longitudinal and shear velocities with wave-propagation direction are presented. The difference in detectability of artificial reflectors using shear waves of varying polarization is presented, and it is demonstrated that, in some cases, horizontally polarized shear waves can detect a reflector in the weld metal, whereas the traditional vertically polarized shear waves cannot.
Date: March 1978
Creator: Kupperman, D. S. & Reimann, K. J.
Partner: UNT Libraries Government Documents Department

An Ultrasonic Scanner for Stainless Steel Weld Inspections

Description: The large grain size and anisotropic nature of stainless steel weld metal make conventional ultrasonic testing very difficult. This paper evaluates a technique for minimizing the coherent noise in stainless steel weld metal. The method involves digitizing conventional A-scan traces and averaging them with a minicomputer. Results are presented for an ultrasonic scanner which interrogates a small volume of the weld metal while averaging the coherent ultrasonic noise.
Date: September 1978
Creator: Kupperman, D. S. & Reimann, K. J.
Partner: UNT Libraries Government Documents Department

Nondestructive evaluation techniques for silicon carbide heat-exchanger tubing

Description: The adequacy of various nondestructive evaluation (NDE) techniques for inspecting silicon carbide heat-exchanger tubing is discussed. These methods include conventional ultrasonics, acoustic microscopy, conventional and dye-enhanced radiography, holographic interferometry and infrared scanning techniques. On the basis of current test results and an examination of the discussions in available literature, these techniques were compared with respect to (a) effectiveness in detecting cracks, pitting, inclusions, and voids, (b) effectiveness in characterizing detected flaws, (c) adaptability to tube geometry, (d) adaptability to in-service inspection, (e) reliability, and (f) extent of development required for commercialization.
Date: January 1, 1979
Creator: Kupperman, D.S.; Deininger, W.D.; Lapinski, N.P.; Sciammarella, C. & Yuhas, D.
Partner: UNT Libraries Government Documents Department

Nondestructive Evaluation Techniques for Silicon Carbide Heat-Exchanger Tubes : Annual Report, October 1977-September 1978

Description: This report discusses the adequacy of several nondestructive evaluation techniques for the detection of flaws in silicon carbide heat-exchanger tubing. Experimental results have been obtained for conventional ultrasonic testing, acoustic microscopy, conventional and dye-enhanced radiography, holographic interferometry, infrared scanning and internal-friction measurements.
Date: March 1979
Creator: Kupperman, D. S.; Yuhas, D.; Sciammarella, Cesar A.; Lapinski, N. P. & Fiore, N. F.
Partner: UNT Libraries Government Documents Department

Nondestructive Evaluation Techniques for Silicon Carbide Heat-Exchanger Tubes : Second Annual Report, October 1978-September 1979

Description: This report discusses the development of ultrasonic testing, acoustic microscopy, dye-enhanced radiography, holographic interferometry, and infrared scanning techniques for flaw detection in silicon carbide (SiC) heat-exchanger tubing. Both preservice and in-service testing requirements are discussed. An ultrasonic boreside probe and an acoustic microscope stage have been designed for continuous monitoring of SiC tubing. Preliminary results with these acoustic systems are presented. In addition, a novel technique for detecting small surface flaws using holographic interferometry is discussed. Fracture mechanics analysis suggests that detection of flaws on the order of 100 um is necessary to assure good reliability of ceramic heat exchangers. The acoustic and holographic techniques have been shown to be capable of detecting flaws of this size. However, the sensitivity of ultrasonic flaw detection in SiC is affected by the microstructure of the component. The practical considerations involved in the use of these techniques are discussed.
Date: November 1979
Creator: Kupperman, D. S.; Yuhas, D.; Deininger, W. & Sciammarella, Cesar A.
Partner: UNT Libraries Government Documents Department

Development of Nondestructive Evaluation Techniques for High-Temperature Ceramic Heat Exchanger Components : Third Annual Report, October 1979-September 1980

Description: The goals of the present program are not only to develop hardware and procedures for efficiently inspecting ceramic heat-exchanger components in conventional ways, but also to develop advanced NDE techniques that will allow effective failure prediction. The main objectives in FY 1980 have been to (a) develop a computer-interfaced ultrasonic bore-side probe for pre-service and in-service inspection, (b) develop and assess techniques for inspection of SiC tubing by acoustic microscopy, and (c) carry out preliminary tests to compare ultrasonic, holographic, and infrared techniques with more conventional dye-penetrant and radiographic methods for inspection of butt joints in ceramic tubes. Circumferential notches, 125 microns deep x 250 microns long, on the inner and outer surfaces of sintered and siliconized SiC tubes were successfully detected with an ultrasonic bore-side probe. The acoustic microscope was modified to handle 30- as well as 100-MHz sound waves, since the lower-frequency waves give better penetration of Sic tube walls. The modification decreased the acoustic noise. The ability to detect a notch only 250 x 125 x 75 microns in size was demonstrated. Efforts to examine a butt joint with dye-penetrant, radiographic, ultrasonic, and holographic-interferometry techniques revealed that while holography seemed to identify more clearly the presence of a crack-like inner surface flaw, ultrasonic pulse-echo and pitch-catch techniques at 22 MHz also indicated the presence of an anomaly; the ultrasonic and holographic results agreed with regard to angular location of the flaw.
Date: 1980
Creator: Kupperman, D. S.; Yuhas, D.; Sciammarella, Cesar A.; Caines, M. J. & Winiecki, A.
Partner: UNT Libraries Government Documents Department

Deviation of longitudinal and shear waves in austenitic stainless steel weld metal

Description: One of the difficulties associated with the ultrasonic inspection of stainless steel weld metal is the deviation of the ultrasonic beams. This can lead to errors in determining both the location and size of reflectors. The present paper compares experimental and theoretical data related to beam steering for longitudinal and shear waves in a sample of 308 SS weld metal. Agreement between predicted and measured beam deviations is generally good. Reasons for discrepancies are discussed.
Date: January 1, 1980
Creator: Kupperman, D.S. & Reimann, K.J.
Partner: UNT Libraries Government Documents Department

Advanced Fuel Cell Development Progress Report: October-December 1979

Description: Quarterly report discussing fuel cell research and development work at Argonne National Laboratory (ANL). This report describes efforts directed toward understanding and improving components of molten carbonate fuel cells and have included operation of 10-cm square cells.
Date: May 1980
Creator: Pierce, R. D.; Kucera, G. H.; Kupperman, D. S.; Poeppel, R. B.; Sim, J. W.; Singh, R. N. et al.
Partner: UNT Libraries Government Documents Department

Effect of Welding Procedure and Aging on Ultrasonic Wave Propagation in Austenitic Stainless Steel

Description: Various types of austenitic stainless steel (SS) were aged for up to 2500 h at a temperature of 600C to determine whether the resultant microstructural changes would affect the ultrasonic velocity and attenuation and thus the reliability of ultrasonic in-service inspections. Samples of Type 304 and 316 SS as well as 308, 308CRE, and 316 weld metal were examined. Velocity variations were less than 1%, and attenuation variations at frequencies below 10 MHz were not significant except in the anomalous case of one Type 316 SS weldmetal sample. That change may be due to unexpected microstructural changes associated with aging. The variation in the samples attributed to aging is therefore not expected to have a deleterious effect on ultrasonic in-service inspection of stainless steel reactor components.
Date: July 1980
Creator: Kupperman, D. S.; Caines, M. J.; Reimann, K. J. & Fiore, N. F.
Partner: UNT Libraries Government Documents Department

Application of NDE methods to green ceramics: initial results

Description: The effectiveness of microradiography, ultrasonic methods, unclear magnetic resonance, and neutron radiography was assessed for the nondestructive evaluation of green (unfired) ceramics. The application of microradiography to ceramics is reviewed, and preliminary experiments with a commercial microradiography unit are described. Conventional ultrasonic techniques are difficult to apply to flaw detection green ceramics because of the high attenuation, fragility, and couplant-absorbing properties of these materials. However, velocity, attenuation, and spectral data were obtained with pressure-coupled transducers and provided useful informaion related to density variations and the presence of agglomerates. Nuclear magnetic resonance (NMR) imaging techniques and neutron radiography were considered for detection of anomalies in the distribution of porosity. With NMR, areas of high porosity might be detected after the samples are doped with water. In the case of neutron radiography, although imaging the binder distribution throughout the sample may not be feasible because of the low overall concentration of binder, regions of high binder concentration (thus high porosity) should be detectable.
Date: January 1, 1983
Creator: Kupperman, D.S.; Karplus, H.B.; Poeppel, R.B.; Ellingson, W.A.; Berger, H.; Robbins, C. et al.
Partner: UNT Libraries Government Documents Department

Developmental techniques for ultrasonic flaw detection and characterization in stainless steel. [PWR]

Description: Flaw detection and characterization by ultrasonic methods is particularly difficult for stainless steel. This paper focuses on two specific problem areas: (a) the inspection of centrifugally cast stainless steel (CCSS) and (b) the differentiation of intergranular stress-corrosion cracking (IGSCC) from geometrical reflectors such as the weld root. To help identify optimal conditions for the ultrasonic inspection of CCSS, the effect of frequency on propagation of longitudinal and shear waves was examined in both isotropic and anisotropic samples. Good results were obtained with isotropic CCSS and 0.5-MHz angle beam shear waves. The use of beam-scattering patterns (i.e. signal amplitude vs skew angle) as a tool for discriminating IGSCC from geometrical reflectors is also discussed.
Date: April 1, 1983
Creator: Kupperman, D.S.
Partner: UNT Libraries Government Documents Department

Acoustic leak detection and ultrasonic crack detection

Description: A program is under way to assess the effectiveness of current and proposed techniques for acoustic leak detection (ALD) in reactor coolant systems. An ALD facility has been constructed and tests have begun on five laboratory-grown cracks (three fatigue and two thermal-fatigue and two field-induced IGSCC specimens. After ultrasonic testing revealed cracks in the Georgia Power Co. HATCH-1 BWR recirculation header, the utility installed an ALD system. Data from HATCH-1 have given an indication of the background noise level at a BWR recirculation header sweepolet weld. The HATCH leak detection system was tested to determine the sensitivity and dynamic range. Other background data have been acquired at the Watts Bar Nuclear Reactor in Tennessee. An ANL waveguide system, including transducer and electronics, was installed and tested on an accumulator safety injection pipe. The possibility of using ultrasonic wave scattering patterns to discriminate between IGSCCs and geometric reflectors has been explored. Thirteen reflectors (field IGSCCs, graphite wool IGSCCs, weld roots, and slits) were examined. Work with cast stainless steel (SS) included sound velocity and attenuation in isotropic and anisotropic cast SS. Reducing anisotropy does not help reduce attenuation in large-grained material. Large artificial flaws (e.g., a 1-cm-deep notch with a 4-cm path) could not be detected in isotropic centrifugally cast SS (1 to 2-mm grains) by longitudinal or shear waves at frequencies of 1 MHz or greater, but could be detected with 0.5-MHz shear waves. 13 figures.
Date: October 1, 1983
Creator: Kupperman, D.S.; Claytor, T.N. & Groenwald, R.
Partner: UNT Libraries Government Documents Department

Evaluation of methods for leak detection in reactor primary systems and NDE of cast stainless steel

Description: Six cracks, including two field-induced IGSCC specimens and two thermal-fatigue cracks, have been installed in a laboratory acoustic leak detection facility. The IGSCC specimens produce stronger acoustic signals than the thermal-fatigue cracks at equivalent leak rates. Despite significant differences in crack geometry, the acoustic signals from the two IGSCC specimens, tested at the same leak rate, are virtually identical in the frequency range from 200 to 400 kHz. Thus, the quantitative correlations between the acoustic signals and leak rate in the 300 to 400 kHz band are very similar for the two IGSCC specimens. Also, acoustic background data have been acquired during a hot functional sensitivity of acoustic leak detection techniques. In addition, cross-correlation techniques have been successfully used in the laboratory to locate the source of an electronically simulated leak signal.
Date: January 1, 1984
Creator: Kupperman, D.S.; Claytor, T.N.; Prine, D.W. & Mathieson, T.A.
Partner: UNT Libraries Government Documents Department

Application of NDE methods to green ceramics: initial results

Description: This paper describes a preliminary investigation to assess the effectiveness of microradiography, ultrasonic methods, nuclear magnetic resonance, and neutron radiography for the nondestructive evaluation of green (unfired), ceramics. Objective is to obtain useful information on defects, cracking, delaminations, agglomerates, inclusions, regions of high porosity, and anisotropy.
Date: March 1, 1984
Creator: Kupperman, D.S.; Karplus, H.B.; Poeppel, R.B.; Ellingson, W.A.; Berger, H.; Robbins, C. et al.
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

Application of ultrasonic waves to assess grain structure in cast stainless steel

Description: Although the ASME code requires the inspection of cast stainless steel (CSS) piping in nuclear reactors, it has not been possible to demonstrate unambiguously that current inspection techniques are adequate. Ultrasonic inspection is difficult because the microstructure of CSS can vary considerably, from elastically isotropic with equiaxed, relatively small grains to elastically anisotropic with a columnar grain structure to a combination of the two. For the near term, improvements that may increase the reliability of ultrasonic inspection include (a) the development of methods to establish the microstructure of the material (to help optimize the inspection technique), (b) the identification of calibration standards that are more representative of the material to be inspected and (c) the use of cracked CSS samples for training purposes. In this paper, the results of experiments to characterize the microstructure of CSS by use of ultrasonic waves will be discussed. Shear waves may be more effective for isotropic material, whereas longitudinal waves may be better for the anisotropic case because of beam-focusing effects. Sound velocity and beam skewing can be measured accurately enough to characterize CSS even in thick-walled reactor components. 5 refs., 6 figs., 2 tabs.
Date: April 1, 1985
Creator: Kupperman, D.S.; Reimann, K.J. & Abrego-Lopez, J.
Partner: UNT Libraries Government Documents Department

Characterization of acoustic emission signals generated by water flow through intergranular stress corrosion cracks

Description: A program is under way at Argonne National Laboratory (ANL) to develop an independent capability to assess the effectiveness of current and proposed techniques for acoustic leak detection (ALD) in reactor coolant systems. The program will establish whether meaningful quantitative data on flow rates and leak location can be obtained from acoustic signatures of leaks due to intergranular stress corrosion cracks (TGSCCs) and fatigue cracks, and whether these can be distinguished from other types of leaks. 5 refs., 3 figs.
Date: May 1, 1985
Creator: Claytor, T.N. & Kupperman, D.S.
Partner: UNT Libraries Government Documents Department

Current practice and developmental efforts for leak detection in US reactor primary systems

Description: Current leak detection practices in 74 operating nuclear reactors have been reviewed. Existing leak detection systems are adequate to ensure a leak-before-break scenario in most situations, but no currently available, single method combines optimal leakage detection sensitivity, leak-locating ability, and leakage measurement accuracy. Simply tightening current leakage limits may produce an unacceptably large number of unnecessary shutdowns. The use of commercially available acoustic monitoring systems or moisture-sensitive tape may improve leak detection capability at specific sites. However, neither of these methods currently provides source discrimination (e.g., to distinguish between leaks from pipe cracks and valves) or leak-rate information (a small leak may saturate the system). A field-implementable acoustic leak detection system is being developed to address these limitations. 5 refs., 3 figs.
Date: July 1, 1985
Creator: Kupperman, D.S. & Claytor, T.N.
Partner: UNT Libraries Government Documents Department