Noboru Jimbo

A Numerical Study on Faraday-Type Electromagnetic Flowmeter in Liquid Metal System, (I): A Numerical Method Based on Magnetic Field and Electric Potential Field: FALCON Code

To predict the three-dimensional steady-state structure of electromagnetic phenomena in the Faraday-type Electromagnetic Flowmeter (EMF), a numerical simulation method using the Galerkin finite element method has been adopted and formatted as a computer code, FALCON. As the induction equation for the induced magnetic field that is important in a liquid metal system, we have presented B-φ formulation for the induced magnetic field and the electric potential field and A-φ formulation for the vector potential field and the electric potential field, and compared the computational efficiency of both formulations. We have selected the B-φ formulation. The computer simulation of the EMF of the MONJU secondary cooling system has been performed and the calculations have shown a good agreement with the calibration test data. We have investigated qualitatively how far the influence of the end effect extends and the characteristics of the voltage response. Overall, this study has indicated that the present method can be applied to the estimation of the characteristics of an EMF and the design of a new EMF.

Remote Field Eddy Current Testing for SG Inspection of Fast Reactor

We confirmed defect detection performance of a remote field eddy current testing (RFECT) in order to inspect a helical-coil-type double wall tube steam generator (DWTSG) with a wire mesh layer for the new-type small fast reactor 4S (Supersafe, Small and Simple). As high sensitivity techniques, to increase an indirect magnetic field intensity, we focused attention on increasing a direct magnetic field intensity in the vicinity of an exciter coil by the use of an exciter coil with a magnetic material (flux guide). We adopted horizontal type multiple detector coils with flux guides arrayed circumferentially to enhance sensitivity of radial direction. According to the experimental results, the indirect magnetic field intensity (the voltage of detector coil in the region of indirect magnetic field) increased more than 100 times by the application of the exciter and detector coils with flux guides. Finally, we detected the pinhole defect of 1 mm in diameter and 20% of outer tube thickness in depth over the wire mesh layer by the adoption of the flux guides and horizontal type multiple detector coils. And we confirmed that the RFECT probe is also useful to detect the thinning defects.© 2010 ASME