Steam generator small bore piping socket weld inspection using the phased array ultrasonic technique

As nuclear power plants age, the likelihood of failures in the small bore piping used in those plants caused by exposure to mechanical vibrations during plant operations increases. While small bore piping failures rarely cause plant shutdown, the management of small piping has been a keen area of interest since their repair or maintenance requires a reactor trip. Steam generator (SG) drain pipe socket welds are small diameter piping connections (nominal pipe schedule 3–4 inches) susceptible to mechanical vibration. SG drain pipe socket weld failures have caused coolant leakage. Therefore, more reliable inspection technologies for small bore piping need to be developed to detect problems at an early stage and prevent pipe failures. This research aims to improve the reliability and accuracy of small bore piping inspections through the design, manufacture and application of a new phased array ultrasonic testing technique and inspection system for SG drain line socket welds.     

Availability study of a phased array ultrasonic technique

A phased array ultrasonic testing method is expected to be applicable to nuclear power plants for electrical ultrasonic beam control and real time B-scope image display. The availability of the phased array ultrasonic technique has been investigated and it has been verified that the sound beam is electrically steered to the intended angle and is electrically focused at the intended position. From the results of experiments, the dynamic aperture sizing technique was established as a practical method and this technique was demonstrated for artificial flaws.     

Improved ultrasonic testing by phased array technique and its application

The phased array ultrasonic testing method is available for beam steering and focusing, and then the focused beam divergence angle can be narrowed and the sound level can be intensified at the focused region. In the present study, two examples of phased array application which are the linear scanning mode operation and the sector scanning mode operation, were conducted in order to establish the availability of this technique as an actual NDT technique. As the result of the experiments, it was recognized that both types of scanning mode had the capability for defect detection and successful estimation of the defect size. Furthermore, it was well realized that the real time B-scope display without mechanical scanning was effective to reduce the operating time of inspection.     

微波S波段相控阵天线相位的高精度测量研究

为进一步研究受控核聚变,EAST托卡马克将采用3.7GHz低杂电流驱动系统.本文根据3.7GHz低杂波相位控制系统的鉴相要求,采用先下变频,再用数字正交鉴相的设计方案,实现了相位的高精度测量.     

Improvement of SH-wave EMAT phased array inspection by new eight segment probes

This paper presents a newly developed electromagnetic acoustic transducers (EMAT) probe with eight transmitter and eight receiver segments aiming to improve performance of a phased array EMAT probe with four transmitter and four receiver segments. Results of tests on artificial flaws in HAZ in a 6 inch diameter austenitic mock-up pipe were shown for characterizing its performance. The UT result with a conventional Piezo transducer was also referred for comparison.     

Thermal characterisation of ceramic/metal joining techniques for fusion applications using X-ray tomography

This work investigates the thermal performance of four novel CFC–Cu joining techniques. Two involve direct casting and brazing of Cu onto a chromium modified CFC surface, the other two pre-coat a brazing alloy with chromium using galvanisation and sputtering processes. The chromium carbide layer at the interface has been shown to improve adhesion. Thermal conductivity across the join interface was measured by laser flash analysis. X-ray tomography was performed to investigate micro-structures that might influence the thermal behaviour. It was found that thermal conductivity varied by up to 72%. Quantification of the X-ray tomography data showed that the dominant feature in reducing thermal conductivity was the lateral spread of voids at the interface. Correlations were made to estimate the extent of this effect.     

Analysis of double stub tuner control stability in a phased array antenna with strong cross-coupling

Active stub tuning with a fast ferrite tuner (FFT) has greatly increased the effectiveness of fusion ion cyclotron range of frequency (ICRF) systems (50–100 MHz) by allowing for the antenna system to respond dynamically to changes in the plasma load impedance such as during the L–H transition or edge localized modes (ELMs). A high power waveguide double-stub tuner is under development for use with the Alcator C-Mod lower hybrid current drive (LHCD) system at 4.6 GHz. The amplitude and relative phase shift between adjacent columns of an LHCD antenna are critical for control of the launched n_|| spectrum. Adding a double-stub tuning network will perturb the phase and amplitude of the forward wave particularly if the unmatched reflection coefficient is high. This effect can be compensated by adjusting the phase of the low power microwave drive for each klystron amplifier. Cross-coupling of the reflected power between columns of the launcher must also be considered. The problem is simulated by cascading a scattering matrix for the plasma provided by a linear coupling model with the measured launcher scattering matrix and that of the FFTs. The solution is advanced in an iterative manner similar to the time-dependent behavior of the real system. System performance is presented under a range of edge density conditions from under-dense to over-dense and a range of launched n_||. Simulations predict power reflection coefficients (Γ²) of less than 1% with no contamination of the n_|| spectrum. Instability of the FFT tuning network can be problematic for certain plasma conditions and relative phasings, but reducing the control gain of the FFT network stabilizes the system.     

Development of an ultra sonic phased array system for nondestructive tests of nuclear power plant components

A phased array ultrasonic inspection (PAULI) system is being developed to obtain electronically scanned ultrasonic images of the inside of nuclear power plant components for nondestructive evaluation. The development strategy of PAULI system was the modification of a medical ultrasound imaging system that had 64 individual transceiver channels. Optimization of array transducers has been also pursued based on the systematic investigation of the radiation beam field simulated by the use of the boundary diffraction wave models. 7.5 MHz phased array transducers was, then, fabricated and tested with the carbon steel specimen having side-drilled holes. For the nondestructive tests on power plant component, a sample mockup of turbine blade root with EDM notches was fabricated and the detection capability was demonstrated. The developed system can provide electronically scanned ultrasonic images in real time fashion and greatly enhance the efficiency and reliability in the flaw detection and location in comparison with the classical ultrasonic testing (UT) using A-scan signals. For the flaw classification, the analysis of the electronically scanned ultrasonic images was not sufficient at this moment but analysis of features obtained from A-scan signals of flaws at the various steering angles showed the potential capability.     

Signal validation techniques and power plant applications

Computerized signal validation is a software technique for integrating information from redundant and from functionally diverse sensors to provide highly reliable information to operating crews and to auto matic controllers. High reliability results from greater and more comprehensive use of existing sensor redundancy, and from inherent fault detection and isolation (FDI) of faulty sensors.

Operating crews at power plants have always performed some measure of manual signal validation. With the current thrust to introduce digital computers to support plant monitoring and operator aid functions# signal validation has become generally recognized as a key element in the interface between plant sensors and algorithms using sensor data. For any computerized system to be robust and to yield a false alarm rate that is credibly low, high information reliability must be assured at the front end.

Progress of research in computerized signal validation techniques has benefited the U.S. utilities by improving the reliability of safety parameter display systems (SPDS) implemented in the nuclear power plants. Conventional signal validation techniques have been combined with more robust parity space and analytic redundancy methods to provide reliable and real-time SPDS monitoring information to PWR and BWR operators. The technical details of the methods, application to PWR and BWR SPDS, and the extension of the techniques to plant control functions are reviewed in this paper.     

Recent applications of nuclear microprobe techniques to microelectronics

Applications of nuclear microprobe techniques to microelectronics, in particular, two- or three-dimensional analysis of integrated circuit structures using micro RBS (Rutherford Backscattering) and IBIC (Ion Beam Induced Current) measurements are discussed. SEU (Single Event Upset) mapping and IBIC measurements in SRAMs (Static Random Access Memories) and DRAMs (Dynamic Random Access Memories) are reviewed together with charge carrier collection simulation and transient IBIC measurements. Importance of applications of microprobes to new microelectronic structures such as SOI (Silicon-on-Insulator) devices for future hand-held information systems are also discussed. Possible applications of SEU measurement as alternative experimental procedures to cosmic ray neutron strikes are discribed.     

Particle simulations on propagation and resonance of lower hybrid wave launched by phased array antenna in linear devices

In this work, we performed first-principles electromagnetic-kinetic simulations to study a phased antenna array and its interaction with deuterium plasmas within the lower hybrid range of frequency. We first gave wave accessibility and resonance results, which agree well with theoretical prediction. In addition, we further investigated the antenna power spectrum with different antenna phases in the presence of the plasma and compared it with that in a vacuum, which directly indicates wave coupling and plasma absorption. Furthermore, for the case with zero phasing difference, our simulation results show that, albeit the launch is away from the accessibility region, tunneling effect and mode conversion occurred, which enhanced coupling and absorption. Moreover, consistent interactions between the injected wave and the plasma concerning various antenna phase differences are shown. We presented the inchoate response of the plasma in terms of the launching directions. Our results could be favorable for the engineering design of wave heating experiments with a tunable phased antenna array in linear devices, such as simple magnetic mirrors or tandem mirrors.     

New fabrication techniques for components

This paper presents the high quality level of nuclear technology in the Federal Republic of Germany, which has been achieved by the consistent application of advanced manufacturing techniques. Therefore the synchronous development and sophistication of manufacturing process coupled with the utilization of optimized materials is demonstrated by two typical examples. The forged prechamber of the residual heat exchangers as well as the inductive bending of thick-walled pipes show that the use of complex forgings and of L- and Z-shaped piping may guarantee perfectly satisfactory fabrication and testing conditions while at the same time a reduction in the fabrication and testing costs may be achieved.     

核分析技术在基础医学研究中的若干应用

应用同步辐射Ｘ荧光微探针（ＳＲ－ＸＭＦ）和扫描质子微探针（ＳＰＭ）技术研究了基础医学领域中与微量元素有关的几个课题。初步实验结果表明，具有高灵敏度、高分辨率和对样品损伤小的ＳＲ－ＸＭＦ和ＳＰＭ技术特别适合于元素含量低的细胞和生物组织样品，这些技术是研究元素的细胞生理学，从细胞水平探讨微量元素的生物学作用机理以及从微观角度阐明疾病的致病机理等方面有独特作用的新手段。     

Two-dimensional X-ray imaging using plastic scintillating fiber array

Due to its low cost, flexibility and convenience for long distance data transfer, plastic scintillation fiber （PSF） have been increasingly used in building detectors or sensors for detecting various radiations and imaging. In this work, the performance of using PSF coupled with charge-coupled devices （CCD） to build area detectors for 2D X-ray imaging is studied. We describe the experimental setup and show the obtained images from CCD. Modulation Transfer Function （MTF） of the PSF array is also presented and compared to earlier reports.     

新型的核乳胶探测技术

介绍了三种可以准确,快速,半自动（全自动）测量的核乳实验新技术,这些技术特别适合于测量超高能重离子碰撞中心事例中带电粒子的发射角。     

Materials analysis using ion beam techniques

Basic concepts of ion beam analysis techniques for the study of the composition and structure of surfaces, interfaces and thin layers are reviewed. For surface characterization the use of low-energy (1–20 keV) ions is compared with the use of medium-energy (50–200 keV) and high-energy (200 keV-several MeV) ions. Thin-layer analysis with Rutherford backscattering (RBS) and nuclear reaction analysis in combination with channeling is described in detail. Requirements, including the necessary precision demands, for the instrumentation are discussed. The analysis via computer simulations of channeling data, in particular of data for the determination of lattice sites of solute atoms in single crystals, will be treated. As an illustration of the potential of ion beam techniques for structure analysis, a number of examples of lattice site locations is presented.     

Thermal-hydraulic assessment of high heat flux removal techniques for fusion applications

This paper is an assessment of three possible thermal-hydraulic high heat flux heat removal techniques which will result in adequate heat removal from fusion components with minimum penalty. The heat removal alternatives are: (1) subcooled flow boiling (SFB) with water, (2) high velocity helium gas convection (HGC), and (3) liquid metal (LM) heat transfer in the presence of a transverse magnetic field (TM). Advantages and disadvantages of each technique are delineated. Each heat removal technique is examined for a case study applicable to near-term fusion components such as limiters and divertors.Comparisons are made for the selected case study involving heat removal from a 1.5 m long, 1.0 cm diameter (inside) coolant channel which is subjected to a unifirm steady-state heat flux of 0.5 kW/cm². The results show that SFB has the greatest heat removal capability, with the lowest coolant channel wall temperature and pumping power, followed by HGC and LMTM. Critical research and development needs for each technique are also summarized.     

Development of an ultrasonic inspection system using array transducers

A new ultrasonic inspection system was developed to obtain ultrasonic images of defects. This system adopts an electronic beam control method using array transducers. The beam control modes are a compound scanning mode and a linear scanning mode. Both modes are performed by timing control of ultrasonic wave transmission and reception at each transducer element.In the focal beam, the refraction of the ultrasonic wave at the boundary between water and metal in immersion testing is utilized to improve the lateral resolution of the ultrasonic beam. In steel, the improvement is a maximum of 25% for focal lengths from 5 to 35 mm as compared to lateral resolution not utilizing refraction.This system successfully imaged two side drilled holes in a steel block.     

Comparison between beam-stop and beam-hole array scatter correction techniques for industrial X-ray cone-beam CT

In industrial X-ray cone-beam computed tomography, the inspection of large-scale samples is important because of increasing demands on their quality and long-term mechanical resilience. Large-scale samples, for example made of aluminum or iron, are strongly scattering X-rays. Scattered radiation leads to artifacts such as cupping, streaks, and a reduction in contrast in the reconstructed CT-volume. We propose a scatter correction method based on sampling primary signals by employing a beam-hole array (BHA). In this indirect method, a scatter estimate is calculated by subtraction of the sampled primary signal from the total signal, the latter taken from an image where the BHA is absent. This technique is considered complementary to the better known beam-stop array (BSA) method. The two scatter estimation methods are compared here with respect to geometric effects, scatter-to-total ratio and practicability. Scatter estimation with the BHA method yields more accurate scatter estimates in off-centered regions, and a lower scatter-to-total ratio in critical image regions where the primary signal is very low. Scatter correction with the proposed BHA method is then applied to a ceramic specimen from power generation technologies. In the reconstructed CT volume, cupping almost completely vanishes and contrast is enhanced significantly.