C-1-1

Effective technology of preventive measures against piping damage on steam lines in nuclear power plants

Toshinori TAKATA, Takayuki MORII (TLV CO.,LTD.)

Abstract
Nuclear power plants are required to have especially high reliability and increasingly longer service life. As a contribution to the solution of these issues, troubles unique to nuclear power plants caused by two-phase flow of steam/condensate were identified through analysis from a new perspective on problem areas and causes focusing on the steam field using a database that tracks troubles at nuclear power plants. Additionally, useful technology for prevention against the effects of these troubles that occur in steam/condensate piping, such as erosion-induced pipe wall thinning and potential water hammer, are reported under the categories of 1) steam lines, 2) condensate lines, 3) measurement, inspection or monitoring of equipment or piping.

Keywords
Nucia, Pipe wall Thinning, LDI, Water hammer, Steam trap

C-1-2

Development of Guided Wave Simulator using FDTD method and its Application to Nondestructive Testing

Fumio KOJIMA, Akinori FURUSAWA and Kazuki HASE (Kobe University)

Abstract
This paper is concerned with development of guided wave simulator on piping diagnostic system. First, a mathematical model of inspection procedures is described by a set of dynamical linear elastic equations in three spatial dimensions. Secondly, the numerical scheme of the inspection model is given by using FDTD method. Finally, some numerical experiments are shown in order to assure the applicability of the proposed scheme to piping test.

Keywords
Simulation, Identification, Nondestructive testing, Numerical analysis

C-1-3

Prediction of Wall Thinning by Flow Accelerated Corrosion using Kalman Filtering

Fumio KOJIMA, Junichi TSUBOTA and Masahiro UEDA (Kobe University)

Abstract
The purpose of this report is to establish a predictive methodology for estimating rate of wall thinning in a piping system used in ageing nuclear power plants. First, mechanism of flow accelerated corrosion caused by steam of flowing water is given by KWU-KR model. Secondly, a method for setting geometrical parameter based on pipe wall thickness measurements is considered. Thirdly, estimation methodology for wall thinning rate is formulated within the framework of Kalman filtering. Finally, some simulation results are demonstrated.

Keywords
Preventive maintenance, condition monitoring, simulation, estimation

C-1-4

Signal Processing for Pipe Wall Thickness Measurements using Electromagnetic Acoustic Resonance Method

Fumio KOJIMA, Daigo KOSAKA and Kosuke UMETANI (Kobe University)

Abstract
This paper is concerned with signal processing arising in pipe wall thinning measurements using electromagnetic acoustic transducer (EMAT). First, electromagnetic acoustic resonance method (EMAR) is applied to pipe wall thickness measurement. Secondly, a heuristic method for extracting features of resonance spectrum obtained by testing data is proposed. Finally, the validity and the feasibility of our proposed method are demonstrated through the practical test at the real plant.

Keywords
Condition monitoring, ultra-sound test, signal processing, acoustic resonance

C-1-5

Measurement and Evaluation of Pipe Wall Thinning by Electromagnetic Acoustic Resonance

Shigeru KANEMOTO (University of Aizu), Ryo-ichi URAYAMA, Tetsuya UCHIMOTO and Toshiyuki TAKAGI (Tohoku University)

Abstract
Electromagnetic acoustic transducer (EMAT) provides non-contacting measurements and is often applied to monitoring in high temperature environment. One of drawbacks of EMAT is its low sensitivity and S/N ratio. One way to overcome the drawback is to introduce an Electromagnetic acoustic resonance method (EMAR); it has a high capability of evaluating thickness or ultrasonic velocity, and it is applied to the measurement of thickness, elastic constants, damping properties and so on. Since the principle of the method is based on the resonances of bulk waves in plates, that is, thickness oscillations, targets are usually limited to ones with simple geometry. In this study, pipe wall thinning, where the thickness changes on the curved surface, is evaluated by EMAR. For the purpose, several data processing methods are applied to extract thickness information from EMAR spectral responses. Measured spectra are obtained by an experiment using a carbon steel pipe with two-dimensional thinning machined by milling, and results of the data processing are compared in view of accuracy and stability. Finally, the data processing method is applied to the EMAR spectra of a pipe specimen cut from a mock-up test loop

Keywords
EMAT, EMAR, Pipe Wall Thinning, Thickness Measurement, Signal Processing

C-1-6

Development of Inspection Method for Pipes by Non Contact Air Coupled Ultrasonic Testing

Masakazu TAKAHASHI, Hidekazu HOSHINO, Yukio OGURA (Japan Probe Co., Ltd), Hideaki KITAGAWA, Hajime WATANABE, Junichi KUSUMOTO and Akihiro KANAYA (KYUSHU ELECTRIC POWER CO. INC.)

Abstract
We have developed the constant incident angle method to inspect pipes by using high power square burst wave in non contact air coupled ultrasonic testing (NAUT). We also succeeded to scan the effective guided wave propagated circumferentially in pipes. This paper describes the optimum frequency, incident angle, the selection of probes and examples of detecting image pictures with the constant incident angle focusing method using focus probe.

Keywords
Constant incident angle, Propagation, Guided waves, Square burst wave, Pipes, NAUT

C-1-7

Plant management which utilized ultrasonic continuous measurement system

Koichi TAMURA, Hiroyuki HAGA and Yuji MATSUO (Asahi Kasei Engineering Corporation)

Abstract
In plant management, aged facilities have been serious problem. Especially, carbon steel causes many accidents on the problem of corrosion. we have managed remaining life time to a use limit, based on the thickness by ultrasonic measurement result in the fixed point. However, most accidents have generated because of the failure to notice localized metal decrease. The authors have developed a continuous thickness measurement system utilizing ultrasonic waves which scans metal loss in tank, and pressure vessel, piping, etc. In this report, the inspection system and application for plant management are briefly shown.

Keywords
Aged facilities, carbon steel, Corrosion, Ultrasonic, Continuous thickness measurement

C-1-8

Radiation Transmission Pipe Thickness Measurement System

Yasuhiko HIGASHI (FUJI ELECTRIC SYSTEMS Co.,Ltd.)

Abstract
Fuji Electric Systems can be measured from the outer insulation of the transmission Characteristics and radiation detection equipment had been developed that can measure Pipe wall thinning in plant and running, the recruitment of another three-beam calculation method by pipe thickness measurement system was developed to measure the thickness of the pipe side. This equipment has been possible to measure the thickness of the circumferential profile of the pipe attachment by adopting automatic rotation.

Keywords
thickness measurement, detection thorough heat insulation , radiation transmission , safety of plants