No abstract available

[en] Development of effective procedures for recovery from the 1979 accident at the Three Mile Island 2 (TMI-2) nuclear station requires a detailed knowledge of the core configuration following the accident. Remote video surveys of limited scope in the summer of 1982 revealed a cavity in the upper core region that seemed to be about 1.5 m deep, extending out to perhaps two-thirds of the core radius. A clearer, more detailed and quantitative description of the postaccident core configuration was needed to plan defueling procedures. This work describes the techniques used for precise ultrasonic, sonar-like measurements of the core void, and details the primary results

[en] Conventional design practice in commercial and laboratory ultrasonic instrumentation results in performance which is less than ideal for many advanced applications in research and in automated systems. The major problems with most such instrumentation can be traced to inadequate dynamic range and to baseline distortion arising from AC coupling between stages. This is a preliminary report on an ultrasonic pulser and receiver/preamplifier system having greatly expanded sensitivity and lower noise characteristics in many ultrasonic applications. In at least one application of the new instruments, an improvement of 30 to 40 dB in dynamic range can be achieved

No abstract available

[en] An advanced ultrasonic system was developed to obtain highly reproducible inspection data and to overcome certain limitations encountered with the manual scanning method. Experience from field operations from 1976 through 1980 is discussed. The scope includes a description of the computer controlled system, personnel training, inservice inspections, data analysis, and current upgrading of the system

[en] Development of effective procedures for recovery from the 1979 accident at the Three Mile Island 2 nuclear station requires a detailed and quantitative description of the postaccident configuration of the core. This report describes the techniques, equipment, and procedures used for making precise ultrasonic, sonar-like measurements of the cavity left in the upper core region as a result of the accident and details the primary results of the measurements. The system developed for the measurements uses computer techniques for the command and control of remote mechanical and electronic equipment, and for data acquisition and reduction. The system was designed, fabricated, and tested; procedures developed; and personnel trained in 4-1/2 months. The primary results are detailed topographic maps of the cavity. A variety of visual aids was developed to supplement the maps and aid in interpreting companion videotape surveys. The measurements reveal a cavity of 9.3 m³, approximately 26% of the total core volume. The cavity occupies most of the full diameter of the core to an average depth of about 1.5 m and approaches 2 m in places

[en] The Advanced Test Reactor is a 250 MW LWR used primarily for irradiation testing of materials contained in inpile tubes that pass through the reactor core. These tubes provided the high pressure and temperature water environment required for the test specimens. The reactor cooling water surrounding the inpile tubes is at much lower pressure and temperature. The structural integrity of the inpile tubes is monitored by routine surveillance to ensure against unplanned reactor shutdowns to replace defective inpile tubes. The improved instruments developed for inpile tube surveillance include a bore profilometer, ultrasonic flaw detetion system and bore diameter gauges. The design and function of these improved instruments is presented

[en] The requirements for precision and reproducibility of ultrasonic testing during inservice inspection of nuclear reactors are both quantitatively and qualitatively more severe than most current practice in the field can provide. An automated ultrasonic testing (AUT) system, which provides a significant advancement in field examination capabilities, is described. Properties of the system, its application, and typical results are discussed

[en] A miniature ultrasonic search head was developed for computer-controlled inservice inspection of nuclear piping weldments. Major performance objectives were increasing data reproducibility and versatility of inspection techniques and reducing radiation exposure for certified Level II inspectors. The fluid-filled search head houses a toroidal axicon lens, transducer, and folded mirror system that produces either a small diameter near-parallel beam or a defocused beam. The folded mirror system also provides a long fluid path, thus eliminating multiple echoes during the inspection period. Monitoring of beam characteristics and operation of the linear and two angular motions are computer controlled. Data reproducibility is improved by computer control and monitoring of acoustic and mechanical performance characteristics. Versatility is achieved through varied beam shapes and orientations and the flexible diaphragm which permits scanning simple or complex shapes. Extensive automation of field operational steps allows the Level II inspectors, who are in short supply because of radiation burnout, to function primarily from the radiation-free computer console

[en] Ultrasonic inspection of cast austenitic steel components has historically been plagued by difficulties in penetrating the material ultrasonically, low signal/noise ratio (SNR), and false indications. These difficulties are attributed to anisotropy of the elastic properties of relatively large grains. The anisotropy affects both the manner in which individual acoustic modes propagate and the directions in which they can propagate. A majority of research efforts have addressed the anisotropy primarily as it affects individual-mode propagation, using a single-preferred-axis model of the crystallographic structure. That model has not been fully successful in explaining experimental results. An alternative three-dimensionally anisotropic model of the cast austenitics is proposed and tested experimentally