Liquid sodium is used as the coolant in some fast spectrum nuclear reactors. This material is optically opaque. To facilitate operations and maintenance activities, an ultrasonic under-sodium viewing system has been developed. In the USA, the technology was successfully demonstrated in the 1970s and, over the intervening 30+ years, the capability was lost. This paper reports materials challenges encountered in developing both single-element and linear phased-array 2-MHz transducers that must operate at temperatures up to 260 degrees C. The critical issues are fundamentally material selection: the ability of a transducer to be immersed into liquid sodium and function at 260 degrees C, to achieve wetting and transmission of ultrasound into the sodium, and to be able to be removed and re-used.

Cast austenitic stainless steel (CASS) that was commonly used in U.S. nuclear power plants is a coarse-grained, elastically anisotropic material. In recent years, low-frequency phased-array ultrasound has emerged as a leading candidate for the inspection of welds in CASS piping, due to the relatively lower interference in the measured signal from ultrasonic backscatter. However, adverse phenomena (such as scattering from the coarse-grained microstructure, and beam redirection and partitioning due to the elastically anisotropic nature of the material) result in measurements with a low signal-to-noise ratio (SNR), and increased difficulty in discriminating between signals from flaws and signals from benign geometric factors. There is therefore a need for advanced signal processing tools to improve the SNR and enable rapid analysis and classification of measurements. This paper discusses recent efforts at PNNL towards the development and evaluation of a number of signal processing algorithms for this purpose. Among the algorithms being evaluated for improving the SNR (and, consequently, the ability to discriminate between flaw signals and non-flaw signals) are wavelets and other time-frequency distributions, empirical mode decompositions, and split-spectrum processing techniques. A range of pattern-recognition algorithms, including neural networks, are also being evaluated for their ability to successfully classify measurements into two or more classes. Experimental data obtained from the inspection of a number of welds in CASS components are being used in this evaluation.

This report describes research and development efforts toward a novel passive millimeter-wave (mm-wave) electromagnetic imaging device for broad-area search. It addresses the technical challenge of detecting anomalies that occupy a small fraction of a pixel. The purpose of the imager is to pinpoint suspicious locations for cuing subsequent higher-resolution imaging. The technical basis for the approach is to exploit thermal and polarization anomalies that distinguish man-made features from natural features.

PreviousNext No AccessSEG Technical Program Expanded Abstracts 2010Nuclear Source Replacement in Petrochemical Well‐LoggingAuthors: Leonard J. BondJeffrey W. GriffinKayte M. DenslowRobert V. HarrisThomas SchenkelA. PersaudGregory E. DaleAvneet SoodJames T. RutledgeScott KovaleskiFrances KeelLeonard J. BondPacific Northwest National LaboratorySearch for more papers by this author, Jeffrey W. GriffinPacific Northwest National LaboratorySearch for more papers by this author, Kayte M. DenslowPacific Northwest National LaboratorySearch for more papers by this author, Robert V. HarrisPacific Northwest National LaboratorySearch for more papers by this author, Thomas SchenkelLawrence Berkeley National LaboratorySearch for more papers by this author, A. PersaudLawrence Berkeley National LaboratorySearch for more papers by this author, Gregory E. DaleLos Alamos National LaboratorySearch for more papers by this author, Avneet SoodLos Alamos National LaboratorySearch for more papers by this author, James T. RutledgeLos Alamos National LaboratorySearch for more papers by this author, Scott KovaleskiUniversity of MissouriSearch for more papers by this author, and Frances KeelU.S. Department of Energy, National Nuclear Security Administration, Nonproliferation and Verification R&D (NA‐22)Search for more papers by this authorhttps://doi.org/10.1190/1.3513833 SectionsSupplemental MaterialAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Abstract There is concern that sealed, chemical isotope radiation sources, which are currently used in the gas/oil well logging industry, (e.g., AmBe, 252Cf, 61Co and 137Cs), can be diverted and used in radiological dispersal devices or RDD's (“dirty bombs”). Recent actions by the U.S. Department of Energy (DOE) have reduced the availability of these sources in the United States. Alternatives, both radiological and non‐radiological, are actively being sought within the oil‐field services community. To investigate source replacement, the National Nuclear Security Administration (NNSA) is developing a Radiological Source Replacement (RSR) Program. This paper summarizes several current project components of the RSR program. The projects are seeking to determine if the use of isotopic sources can potentially be further reduced and what steps are needed to engage the user community and facilitate reductions in source use. The projects are investigating enabling technologies for non‐nuclear and non‐isotope‐based well logging techniques. Isotopic source reduction requires an assessment of technical feasibility to guide both DOE and the Nuclear Regulatory Commission (NRC) on potential policy updates or changes.Permalink: https://doi.org/10.1190/1.3513833FiguresReferencesRelatedDetailsCited ByNote: Stability and lifetime of scandium deuteride film cathode in a vacuum arc ion sourceReview of Scientific Instruments, Vol. 89, No. 2Lifetime of hydrogenated composite cathodes in a vacuum arc ion sourceReview of Scientific Instruments, Vol. 87, No. 2A compact neutron generator using a field ionization sourceReview of Scientific Instruments, Vol. 83, No. 2 SEG Technical Program Expanded Abstracts 2010ISSN (print):1052-3812 ISSN (online):1949-4645Copyright: 2010 Pages: 4453 publication data© 2010 Copyright © 2010 Society of Exploration GeophysicistsPublisher:Society of Exploration Geophysicists HistoryPublished: 21 Oct 2010 CITATION INFORMATION Leonard J. Bond, Jeffrey W. Griffin, Kayte M. Denslow, Robert V. Harris, Thomas Schenkel, A. Persaud, Gregory E. Dale, Avneet Sood, James T. Rutledge, Scott Kovaleski, and Frances Keel, (2010), "Nuclear Source Replacement in Petrochemical Well‐Logging," SEG Technical Program Expanded Abstracts : 518-522. https://doi.org/10.1190/1.3513833 Plain-Language Summary PDF DownloadLoading ...

Cast austenitic stainless steel (CASS) that was commonly used in U.S. nuclear power plants is a coarse-grained, elastically anisotropic material. The engineering properties of CASS made it a material of choice for selected designs of nuclear power reactor systems. However, the fabrication processes result in a variety of coarse-grain microstructures that are difficult to inspect ultrasonically, largely due to detrimental effects of wave interactions with the microstructure. To address the inspection needs, new approaches that are robust to these phenomena are being sought. However, overcoming the deleterious effects of the coarse-grained microstructure on the interrogating ultrasonic beam will require knowledge of the microstructure and the corresponding acoustic properties of the material, for potential optimization of inspection parameters to enhance the probability of detecting flaws. The goal of improving the reliability and effectiveness of ultrasonic inspection of CASS specimens can therefore potentially be achieved by first characterizing the microstructure of the component. The characterization of CASS microstructure must be done in-situ, to enable dynamic selection and optimization of the ultrasonic inspection technique. This paper discusses the application of ultrasonic measurement methods for classifying the microstructure of CASS components, when making measurements from the outside surface of the pipe or component. Resultsmore » to date demonstrate the potential of ultrasonic and electromagnetic measurements to classify the material type of CASS for two consistent microstructures-equiaxed-grain material and columnar-grain material.« less

Studies conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington focused on assessing the effectiveness of nondestructive examination (NDE) techniques for inspecting control rod drive mechanism (CRDM) nozzles and J-groove weldments. The primary objective of this work is to provide information to the United States Nuclear Regulatory Commission (NRC) on the effectiveness of NDE methods as related to the in-service inspection of CRDM nozzles and J-groove weldments, and to enhance the knowledge base of primary water stress corrosion cracking (PWSCC) through destructive characterization of the CRDM assemblies.

Studies conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, focused on assessing the effectiveness of nondestructive examination (NDE) techniques for inspecting control rod drive mechanism (CRDM) nozzles and J-groove weldments. The primary objectives of this work are to provide information to the U.S. Nuclear Regulatory Commission (NRC) on the effectiveness of NDE methods as related to the in-service inspection of CRDM nozzles and J-groove weldments and to enhance the knowledge base of primary water stress corrosion cracking (PWSCC) through destructive characterization of the CRDM assemblies. Two CRDM assemblies were removed from service, decontaminated, and then used in a series of NDE and destructive examination (DE) measurements; this report addresses the following questions: 1) What did each NDE technique detect? 2) What did each NDE technique miss? 3) How accurately did each NDE technique characterize the detected flaws? 4) Why did the NDE techniques perform or not perform? Two CRDM assemblies including the CRDM nozzle, the J-groove weld, buttering, and a portion of the ferritic head material were selected for this study. This report focuses on a CRDM assembly that contained suspected PWSCC, based on in-service inspection data and through-wall leakage. The NDE measurements used to examine the CRDM assembly followed standard industry techniques for conducting in-service inspections of CRDM nozzles and the crown of the J-groove welds and buttering. These techniques included eddy current testing (ET), time-of-flight diffraction ultrasound, and penetrant testing. In addition, laboratory-based NDE methods were employed to conduct inspections of the CRDM assembly with particular emphasis on inspecting the J-groove weld and buttering. These techniques included volumetric ultrasonic inspection of the J-groove weld metal and visual testing via replicant material of the J-groove weld. The results from these NDE studies were used to guide the development of the destructive characterization plan. The NDE studies found several crack-like indications. The NDE and DE studies determined that one of these was a through-weld, radially oriented PWSCC crack in the wetted surface of the J-groove weld, located at the transition point between the weld and the buttering. The crack was 6 mm long on the surface and quickly grew to 25 mm long at a depth of 8 mm, covering the length of the weld between the penetration tube and the carbon steel. The NDE studies found that only ET was able to detect the through-weld crack. The crack was oriented poorly for the ultrasonic testing and was too tight for accurate dye penetrant testing or visual testing. The ET voltage response of the through-wall crack was 30% of the response from a deep electrical discharge machined notch. Destructive examination showed the crack is PWSCC and that it initiated on the wetted surface, grew and expanded through the weld metal, and exited into the annulus. The crack was branched and discontinuous along its length.

Studies being conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington are focused on assessing the effectiveness of nondestructive examination (NDE) techniques for inspecting control rod drive mechanism (CRDM) nozzles and J-groove weldments. The primary objective of this work is to provide information to the United States Nuclear Regulatory Commission (US NRC) on the effectiveness of NDE methods as related to the in-service inspection of CRDM nozzles and J-groove weldments, and to enhance the knowledge base of primary water stress corrosion cracking (PWSCC) through destructive characterization of the CRDM assemblies. In describing two CRDM assemblies removed from service, decontaminated, and then used in a series of NDE measurements, this paper will address the following questions: 1) What did each technique detect?, 2) What did each technique miss?, and 3) How accurately did each technique characterize the detected flaws? Two CRDM assemblies including the CRDM nozzle, the J-groove weld, buttering, and a portion of the ferritic head material were selected for this study. One contained suspected PWSCC, based on in-service inspection data and through-wall leakage; the other contained evidence suggesting through-wall leakage, but this was unconfirmed. The two CRDMs used in this study were cut from a pressure vessel head that has since been replaced. The selected NDE measurements follow standard industry techniques for conducting in-service inspections of CRDM nozzles and the crown of the J-groove welds and buttering. In addition, laboratory based NDE methods were employed to conduct inspections of the CRDM assemblies, with particular emphasis on inspecting the J-groove weld and buttering. This paper will also describe the NDE methods used and discuss the NDE results. Future work will involve using the results from these NDE studies to guide the development of a destructive characterization plan to reveal the crack morphology and a comparison of the degradation found by the destructive evaluation with the recorded NDE responses.

The design, development, and performance testing of a prototype system known as the Remotely Operated Nondestructive Examination (RONDE)system to examine the knuckle region of a Hanford DST have been completed. The design and fabrication of a scanning bridge to support the Savannah River Site utilizing similar technology was also completed.

This report documents work performed at the PNNL in FY01 to support development of a Remotely Operated NDE (RONDE) system capable of inspecting the knuckle region of Hanford's DSTs. The development effort utilized commercial off-the-shelf (COTS) technology wherever possible and provided a transport and scanning device for implementing the SAFT and T-SAFT techniques.

An in-situ bolting and fastener inspection system has been developed by PNNL under funding from the Department of Energy. The inspection system utilizes an ultrasonic pulse-echo technique to detect very small cracks emanating from the thread root. The primary benefits are the ability to inspect the fastener without its removal, much improved detection sensitivity to small cracks and the intuitive interpretation of the acquired images.