A previously introduced two-dimensional EMAT (Electro-Magnetic Acoustic Transducer) simulation code developed in-house at JAEA, based on both coupling/uncoupling of eddy currents and wave displacement in a non-magnetic material is analyzed against 3D numerical simulations and experimental wave displacements performed by JAPEIC. The experimental setup visualizes wave propagations along the vertical surface of a stainless steel plate using a piezoelectric sensor, while the 3D simulations were performed u...
英字タイトル:
A Two-Dimensional EMAT Code for Non-Magnetic Materials using a Coupled/Uncoupled Formulation

The importance of nuclear security increased after FuNushima Daiichi nuclear power plant accident. Especially as a threat to nuclear power plants, sabotage by insider is worthy of attention. In response to this situation, hand motion is an important part of human activity and it has high contribution to high-accuracy detection of insiders’ sabotage. Moreover, Time series data analysis is a useful method in abnormal behavior detection. In this research, the real-time hand motion detection system was develope...
英字タイトル:
Detection of Insiders’ Sabotage using Time-Series Data Analysis of Hand Motion

Abstract: In this paper, some research activities performed by authors on the Electromagnetic Vondestructive Evaluation (ENDE) for materials and structures of nuclear and other industries are ntroduced. The major contents includes, theoretical and experimental studies on NDT of ultra-li ght material and structures, NDT methods for Thermal Barrier Coating (TBC) inspection, improvement en quantitative NDT method of Stress Corrosio n Crack (SCC), new inspection method for material legradation etc. Research me...
英字タイトル:
Introduction of Some Researches on Electromagnetic NDT

This paper evaluated the probability of detection(POD) of austenitic stainless steel welds from the viewpoint of ultrasonic testing. It presents results of simulation-based POD curves of ultrasonic NDT. The simulation model based on a three-dimensional Finite Element Method (FEM) is presented to perform the data generation. Results of conventional POD considering the depth of flaw are given and the requirement of taking the length of flaw into considered is determined....
英字タイトル:
Probability of detection analysis of ultrasonic NDT applied to austenitic stainless steel welds

Abstract: In nuclear power plants (NPPs), due to flow accelerated corrosion (FAC) and liquid droplet impingement (LDI) of the coolant inside the pipe, there may happen local wall thinning defects on the inner surface of a pipe. Concerning the material of pipes, there are mainly two types, low-carbon steel and stainless steel. In this paper, the feas ibility of quantitative nondestructive evaluation (QNDE) to wall thinning in stainless steel pipes using pulsed eddy current testing (PECT) method is discussed...
英字タイトル:
Quantitative NDE of pipe wall thinning using pulsed eddy current testing method

Recently the importance of nuclear security is increased after Fukushima Daiichi Power Plant accident. Especially as the threat to nuclear power plants, sabotage by insider is significant. In this research, the technology to detect malicious behaviors by insiders was developed by video camera movie. Time series data analysis is a useful method in abnormal behavior detection. However, abnormal behavior detection isn’t enough for nuclear security, future malicious behavior prediction should be considered...
英字タイトル:
Sign Detection of Future Malicious Behavior for Nuclear Security

In this research, a new method was developed to identify the _hand motion” of malicious sabotage behaviors. The Auto-encoder and Auto Associative Neural Network were applied for identification, and the time-series data of finger tips position were used as the training data of these Machine Learning. The identification reliability was more than 66%. ...
英字タイトル:
Detection of Sabotage Motion by Time Series Analysis of Video

The distribution of eddy current is disturbed in the presence of cracks. An equivalent solenoid model and a loop current model were proposed respectively to model the bypasses of eddy currents to the underside and longitudinal end of a crack. Eddy current testing signals were qualitatively analyzed by using the equivalent current models. Simulation showed that the signal due to the bypass of eddy current to the under side of a crack was appropriate for the evaluation of crack depth, and the signal due ...
英字タイトル:
Enhancement of Defect Sizing Ability by ECT Data Fusion

Sabotage by malicious insider is one of significant and serious threats for nuclear security of nuclear power plants. It is difficult, however, to distinguish abnormal behaviors from normal works such as their daily maintenance activities. In this study, a technique was proposed to subdivide the abnormal behavior due to sabotage by image analysis and then to detect and identify the abnormal behavior in real time. ...
英字タイトル:
Proposal of Insider Detection Method for Nuclear Security

This study proposes new signal processing methods to restore surface shapes of flaws from eddy current testing（ECT）signals. A linear discriminant analysis method is applied to ECT signals embedded in multi-dimensional state space to identify flaw signals form background noises in prior. A new concept of equivalent point spread function is introduced, and the real flaw shape is restored by utilizing a deconvolution filter based on Richardson-Lucy algorithm. An EDM notch covered by large welding noises...
英字タイトル:
New Signal Processing Methods for Surface Shape Restoration in Eddy Current